The official report in English on the crash - pdf 5mb
1 History of the flight
On Sunday 3 March 1974, DC-10 – 10, registration TC-JAV, landed at Orly at l002 hrs, as scheduled for flight TK 981 Istanbul-Paris-London on which it was engaged. On landing there were 167 passengers on board, of whom 50 disembarked at Paris. The aircraft was parked on stand A2 of the west satellite of Orly-Sud air terminal, where it was taken over by THY station staff and personnel of the airport services.
As regards the security of the TC-JAY parking stand, theie was a gendarme stationed at a fixed point and surveillance by a mobile patrol of three men.
The refuelling operations entailed the suppiy of 10,350 litres of Jet Al fuel In addition to the airline personnel, Paris Airport staff concerned with flight preparation and traffic operations, baggage and cargo handling, technical operations (apron starter unit, aircraft towing) and aircraft cabin cleaning were involved with the aircraft.
The normal stop is for 1 hour but was increased to 1 hour and 30 minutes because of the last minute embarkation of number of passengers from British Airways and Air France. These fresh passengers numbered 216 and embarked after passing through the routine police checks.
During the stop electrical power was provided by the auxiliary power unit from 1000 hrs until the engines were started (the apron starter unit initially arranged for was not used). The door of the aft cargo compartment on the left-hand side was closed at about 1035 hrs. A radio car of the Air Transport Gendarmerie escorted the aircraft from the stand to the take-off runway threshold.
The sequence of events entailed by the departure procedure included the following, according to the times of the air/ground communications:
1 1 1130 les: t“mt contact with Orly-Prdvol for departure operations.
112400 hrs: clearance by Orly-Sol to taxi to runway 08.
112840 hrs; clearance by Or1y-Airport to line up on the take-off runway – departure route 18' – initial climb to flight level 40.
1 Departure route 18 assigned to the aircraft included the following points: Tournan intersection, Coutommiers and Montdidierand Montdidier
The meteorological conditions were goad:
Wind: 060º/10 kt
Cloud: 2/8 Cumulus at 900 m
Qnh: 1016.2 mb
Qfe: 1004.4 mb
Temperature: 6.2ºC
The aircraft took off at approximately 113030 hrs. The flight then proceeded as follows;
113300 hrs: Orly-Depart cleared the aircraft for flight level 60.
113400 hrs: TC-JAY reported at flight level 60 at which it was subsequently transferred to the North Area Control Centre.
113610 hrs: After contact was made with the Area Control, TC-JAY was cleared to climb to flight level 230.
113635 hrs: The Control asked the aircraft to turn to the left to Montdidier.
113700 hrs: Flight level 70 was reached.
The readout of the flight data recorder shows that, in accordance with the THY operating rules, the climb was probably carried out in the automatic mode of the flight contml system. The end of the twn to Montdidier and stabilization an a heading of 345º occurred at about 1138 hrs, flight level 90 was reached and the CAS was of the order of 30G knots.
Three or four seconds before 114000 hrs, the noise of decompression can be heard on the cockpit voice recording, the co-pilot said: ‘the fuselage has burst’ and the pressurization aural warning sounded.
114013 hrs:
The controller who was following the progress of flight TK 981 heard a confused transmission, a heavy background noise mingled with words in the Turkish language and the pressurization warning and then the overspeed warning. At the same time as the overspeed warning signal was heard, the label with the flight number ‘981’ disappeared from the secondary radar scope. Flight level 130’ remained an the scape for a few moments.
On the primary radar the aircraft echo split in two: one part (which may correspond to the parts ejected from the aircraft) remained stationary at about 24 NM on a bearing of 045º fmm Orly and persisted for two or three minutes; the second part, the echo of the DC-10 itself, continued on a path which curved to the left from heading 350º to. heading 280º.
114041 hrs: The confused transmission ceased to be received by the Control.
114104 bra: A fresh very short transmission was recorded on the ground.
114106/07 hrs: A final transmission was heatd and continued until 114113 hrs. From l 14150 hrs, the contmller made repeated caBs to TK 981 but reoeived no reply.
The various recordings (air/ground communications, cockpit voice recoxder, flight data recorder) show that about 77 seconds. elapsed between the time of decompression and the impact with the ground.
The flight data recorder shows that, in the seconds immediately after depressurization, the speed of No 2 engine dropped sharply and the aircraft tumed to the left (9º) and went into a nosMown attitude. This nose-down attitude increased rapidly (down to -20') and the speed increased (360 knots) although Nos 1 and B engines' had been throttled back. The pitch attitude then decreased progressively to -4º and the speed became steady around 430 knots (800 km/hr>.
TC-JAV crashed in the forest of Ermenonville at the place known as ‘Bosquet de Dammartin’, in the commune of Fontaine-ChaaBs (Oise), about 15 km from the village of Saint-Pathus over which initial decompression and the initial loss of parts of the aircraft occurred. There was nn fire.
At the accident site, 37 km NB of Paris, the airaaft was tlving at high speed, 430 knots (about 500 km/hr). it was banked to the left by about 17º and the angle of descent was of the order of 4º.
The aircraft cut through the forest from east to west and caused damage over a rectangular area of 700 m by 100 m. There were no survivors from among the aircraft occupants.
No call was heard on the distress frequency (121.5 MHz).
3.2 Injuries to persons
Crew 12
Passengers 334
Others
Fatal 346
Non-fatal
None
' Including 6 passengers ejected from the aircraft over Saint-Pathus about 15 km from the main point of impact
3.3 Damage to aircraft
After the ejection of the aft cargo door on the left-land side and of various parts of the aircraft structure (floor, seats), the aircraft literally disintegrated on the subsequent impact at very high speed in the forest.
3.4 Other damage
The Senlis Waterways and Forestry Service has made the following assessment of the damage on the ground:
The damaged area covered 6.55 hectares made up as follows:
0.70 hectare; Scotch pines, 20 to 30 years old;
5.85 hectares: Scotch and maritime pines,,50 to 70 years aid.
The damage is estimated at more than 220,000 Francs.
Showing posts with label Official Report English. Show all posts
Showing posts with label Official Report English. Show all posts
Crew of TC-JAV
2
Crew information
THY is required to operate the DC-10-10 with the following crew members:
2 pilots, 1 flight engineer and 8 or 10 cabin staff.
(In cases where there is no ground engineer permanently stationed at the airport of destination, an additional engineer is carried by the aircraft in order to perform the ground engineer duties)
3.5.1 Flight crew
Aircraft Commander: Mr Nejat Berkoz (Turkish nationality)
Age: 44
Condition: married, two children
Certificates and licences
THY A.0. Air Transport Pilot Licence: F-27, 14, 10. 67; DC-9, 7. 6. 68; DC-10, 8. 3. 73.
Transportation Pilot Licence No 294. Validity of the licence: Medical fitness 20. 8. 74. Flight check: 8. 3. 74.
Flight time:
Grand total: 7,003 hours 10 minutes including 1,392 hours 10 minutes at night. In the type of aircraft to which the accident occurred: 438 hours 15 minutes. During the two months preceding the evident: 25 hours 25 minutes. During the 48 hours preceding the accident: 3 bows 50 minutes.
Aviation career:
After transfer from the Turkish Air Force to THY, Mr Nejat Berkoz piloted the following aircraft: F-27 DC-9 and DC-10.
DC-10 training:
(1) 24 hours training on the DC-10-10 simulator at the Douglas Factory Training
Centre at Los Ange1es, California (24. l. 73 to 29. 1. 73).
(2) Flying training in Turkey: 5 hours (5. 3.73 to 8. 3. 73).
(3) Line check in DC-10: 4 hours 30 minutes on 26. 4. 73; 7 hours 30 minutes on 29. 4. 73.
(4) Advanced training: 8 hours on the simulator with United Airlines at Denver.
Co1orado, USA (18. 9. 73 to 19. 9. 73).
Previous accidents: None
Co-Captain: Mr Oral Ulusman (Turkish nationality)
Age: 38
Condition: married
Certificates and licences:
THY A.0. Air Transport Licence: F-27, 23. 3. 68; DC-9. 5. l. 69; DC-10, 8. 3. 73.
Transportation Pilot Licence No 315
Validity: Medical fitness: 17. 4. 74. FBght check: 8. 3. 74.
Turkish Air Force Brevet: 30. 8. 57.
Flight time:
Grand total: 5,589 hours 25 minutes including 1,425 hours 10 minutes at night.
In the type of aircraft to which the accident occurrence 6Q8 hours 5 minutes.
During the two months preceding the accident: 73 hours 45 minutes.
During the 48 hours preceding the accident: 3 hours 50 minutes.
Aviation career:
After transfer from the Turkish Air Force to THY, Mr Oral Ulusman piloted the following aircraft: F-27, DC-9 and DC-10.
DC-10 training:
(1) 30 hours training on the DC-1D'10 simulator at the Douglas Factory Twining Centre, Los Angeles, California (24. l. 73 to 2. 2. 73).
(2) 5 hours 25 minutes flying training in the DC-10-10 in Turkey:
(3) line check: 7 hours 30 minutes on 28. 4. 73. 6 hours 30 minutes on 14. 5. 73. 3. hours 30 minutes on 11, l. 74.
(4) Advanced tuning: 8 hours simulator training with United Airlines at Denver, Colorado, USA (12. 7. 73 to 13. 7. 73).
Previous accidents None.
Flight Engineer: Mr Bream Ozer (Turkish nationality)
Age:37
Condition: married, three children
Certiticates and licences:
THY A.0. Flight Engineer Licence issued on 8. 3. 73.
Validity: medical fitness; 18; 7. 74. Flight check: 14. 10. 74.
Turkish Air Force Brevet dated 30. S. 57.
Flight time:
Grand total: 2,113 hours 25 minutes including 350 hours at night. In the type of aircraft to which the accident occurred: 775 houri 50 minutes. During the two months preceding the accident: 119 hours 5 minutes. During the 48 hours preceding the accident: 3 hours 50 minutes.
Aviation career: DC-10 training:
(1) 25 haul 35 minutes simulator training at the Douglas Factory Training Centre at Los Angeles, California (24. 1. 73 to 29. 1. 73).
(2) 10 hours DC-10-1O flying training in Turkey (5. 3. 73 to 9. 3. 73). (3) line check;
4 hours 30 minutes on 25. 3. 73.
4 hours 10 minutes on 23. 9. 73.
(4) Advanced training: S hams on simulator training with United Airlines at
Denver, Colorado (14. 10. 73 to 15. 10. 73).
Previous accidents None.
Aircraft Gmnnd Engineer flying in the aircraft: Mr Engin Ucok (Turkish nationality)
Age: 45
Condition: married, 3 children
Certificates and licences:
Second Class Aircraft maintenance (Mechanic) licence No 1SS issued on 19. 10. 67. Aviation career:
Mr Ucok was an aircraft ground engineer employed by THY Technical Management as an aircraft maintenance technician.
On 3 March 1974 the THY engineer permanently stationed at Paris was at htanbul on a technical course. Mr Vcok had been taken on board TC-JAV as his replacement.
According to the THY company his duties were as follows: to supervise loading and unloading, transit maintenance and the supply of jet fuel
3.5.2 Cabin personnel
Chief Steward: Mr Hayri Tezcan (Turkish nationality)
Age:30.
Married, I child.
Certificates and licences:
THY A.0. Steward Licence issued on 20. l. 68.
Fight time:
Grand total: 4,916 hours.In the type of aircraft to which the accident occurred: 569 hours 30 minutes.
Stewardess: Miss Gulay Sonmez (Turkish nationality)
Age: 21. Spinster.
Certificates and licence
THY A.0. Stewardess Licence issued on 18. 8. 71.
Flight time:
Grand total: 1,901 hours 30 minutes.
In the type of aircraft to which the accident occurred: 439 hours 25 minutes.
Stewardess: Miss Nilgun Yilmazer (Turkish nationality)
Age: 23. Spinster.
Certificates and licences:
THY. A.0. Stewardess Licence issued on 11. 5. 72. Ffight time:
Grand total: 1,029 hours 55 minutes.
In the type of aircraft to which the accident occurred: 90 hours.
Stewardess: Miss Sibel Zahin (Turkish nationality)
Age: 22. Spinster.
Certificates and licence:
THY A.0. Stewardess Licence issued on 1 l. 5. 72.
Flight time:
Grand total: 1,262 hours 15 minutes.
In the type of aircraft to which the accident occured: 494 hours 50 minutes.
Stewardess: Miss Semra Hidir (Turkish nationality)
Age: 20. Spinster.
Certificates and licences:
THY A.0. Stewardess Licence issued on 2. 4. 73.
Fhght time:
Grand total: 741 hours 45 minutes.
In the type of aircraft to which the accident occurred: 74 hours 50 minutes.
Stewardess: Miss Fatma Barka (Turkish nationality)
Age: 25. Spinster.
Certificates and licences:
THY. A.0. Stewardess Licence issued on 8. 11. 71.
Flight time:
Grand total: 1,465 hours 50 minutes.
In the type of aircraft to which the accident occurred: 297 hours 40 minutes.
Stewardess: Miss Rona Altinay (Turkish nationality)
Age: 29. Spinster.
Certificates and licences:
THY A.0. Stewardess Licence issued on 11. 1. 67.
Flight time:
Grand total: 4,456 hours.
In the type of aircraft to which the accident occurred: 3S7 hours IS minutes.
Stewardess: Miss Ayse Birgili (Turkish nationality)
Age: 22. Spinster.
Certificates and licence:
THY A.0. Stewardess licence issued on 1. 9. 71.
Flight time:
Grand total: 1,723 hours l5 minutes.
In the type of aircraft to which the accident occurred: 139 hours 5 minutes.
Crew information
THY is required to operate the DC-10-10 with the following crew members:
2 pilots, 1 flight engineer and 8 or 10 cabin staff.
(In cases where there is no ground engineer permanently stationed at the airport of destination, an additional engineer is carried by the aircraft in order to perform the ground engineer duties)
3.5.1 Flight crew
Aircraft Commander: Mr Nejat Berkoz (Turkish nationality)
Age: 44
Condition: married, two children
Certificates and licences
THY A.0. Air Transport Pilot Licence: F-27, 14, 10. 67; DC-9, 7. 6. 68; DC-10, 8. 3. 73.
Transportation Pilot Licence No 294. Validity of the licence: Medical fitness 20. 8. 74. Flight check: 8. 3. 74.
Flight time:
Grand total: 7,003 hours 10 minutes including 1,392 hours 10 minutes at night. In the type of aircraft to which the accident occurred: 438 hours 15 minutes. During the two months preceding the evident: 25 hours 25 minutes. During the 48 hours preceding the accident: 3 bows 50 minutes.
Aviation career:
After transfer from the Turkish Air Force to THY, Mr Nejat Berkoz piloted the following aircraft: F-27 DC-9 and DC-10.
DC-10 training:
(1) 24 hours training on the DC-10-10 simulator at the Douglas Factory Training
Centre at Los Ange1es, California (24. l. 73 to 29. 1. 73).
(2) Flying training in Turkey: 5 hours (5. 3.73 to 8. 3. 73).
(3) Line check in DC-10: 4 hours 30 minutes on 26. 4. 73; 7 hours 30 minutes on 29. 4. 73.
(4) Advanced training: 8 hours on the simulator with United Airlines at Denver.
Co1orado, USA (18. 9. 73 to 19. 9. 73).
Previous accidents: None
Co-Captain: Mr Oral Ulusman (Turkish nationality)
Age: 38
Condition: married
Certificates and licences:
THY A.0. Air Transport Licence: F-27, 23. 3. 68; DC-9. 5. l. 69; DC-10, 8. 3. 73.
Transportation Pilot Licence No 315
Validity: Medical fitness: 17. 4. 74. FBght check: 8. 3. 74.
Turkish Air Force Brevet: 30. 8. 57.
Flight time:
Grand total: 5,589 hours 25 minutes including 1,425 hours 10 minutes at night.
In the type of aircraft to which the accident occurrence 6Q8 hours 5 minutes.
During the two months preceding the accident: 73 hours 45 minutes.
During the 48 hours preceding the accident: 3 hours 50 minutes.
Aviation career:
After transfer from the Turkish Air Force to THY, Mr Oral Ulusman piloted the following aircraft: F-27, DC-9 and DC-10.
DC-10 training:
(1) 30 hours training on the DC-1D'10 simulator at the Douglas Factory Twining Centre, Los Angeles, California (24. l. 73 to 2. 2. 73).
(2) 5 hours 25 minutes flying training in the DC-10-10 in Turkey:
(3) line check: 7 hours 30 minutes on 28. 4. 73. 6 hours 30 minutes on 14. 5. 73. 3. hours 30 minutes on 11, l. 74.
(4) Advanced tuning: 8 hours simulator training with United Airlines at Denver, Colorado, USA (12. 7. 73 to 13. 7. 73).
Previous accidents None.
Flight Engineer: Mr Bream Ozer (Turkish nationality)
Age:37
Condition: married, three children
Certiticates and licences:
THY A.0. Flight Engineer Licence issued on 8. 3. 73.
Validity: medical fitness; 18; 7. 74. Flight check: 14. 10. 74.
Turkish Air Force Brevet dated 30. S. 57.
Flight time:
Grand total: 2,113 hours 25 minutes including 350 hours at night. In the type of aircraft to which the accident occurred: 775 houri 50 minutes. During the two months preceding the accident: 119 hours 5 minutes. During the 48 hours preceding the accident: 3 hours 50 minutes.
Aviation career: DC-10 training:
(1) 25 haul 35 minutes simulator training at the Douglas Factory Training Centre at Los Angeles, California (24. 1. 73 to 29. 1. 73).
(2) 10 hours DC-10-1O flying training in Turkey (5. 3. 73 to 9. 3. 73). (3) line check;
4 hours 30 minutes on 25. 3. 73.
4 hours 10 minutes on 23. 9. 73.
(4) Advanced training: S hams on simulator training with United Airlines at
Denver, Colorado (14. 10. 73 to 15. 10. 73).
Previous accidents None.
Aircraft Gmnnd Engineer flying in the aircraft: Mr Engin Ucok (Turkish nationality)
Age: 45
Condition: married, 3 children
Certificates and licences:
Second Class Aircraft maintenance (Mechanic) licence No 1SS issued on 19. 10. 67. Aviation career:
Mr Ucok was an aircraft ground engineer employed by THY Technical Management as an aircraft maintenance technician.
On 3 March 1974 the THY engineer permanently stationed at Paris was at htanbul on a technical course. Mr Vcok had been taken on board TC-JAV as his replacement.
According to the THY company his duties were as follows: to supervise loading and unloading, transit maintenance and the supply of jet fuel
3.5.2 Cabin personnel
Chief Steward: Mr Hayri Tezcan (Turkish nationality)
Age:30.
Married, I child.
Certificates and licences:
THY A.0. Steward Licence issued on 20. l. 68.
Fight time:
Grand total: 4,916 hours.In the type of aircraft to which the accident occurred: 569 hours 30 minutes.
Stewardess: Miss Gulay Sonmez (Turkish nationality)
Age: 21. Spinster.
Certificates and licence
THY A.0. Stewardess Licence issued on 18. 8. 71.
Flight time:
Grand total: 1,901 hours 30 minutes.
In the type of aircraft to which the accident occurred: 439 hours 25 minutes.
Stewardess: Miss Nilgun Yilmazer (Turkish nationality)
Age: 23. Spinster.
Certificates and licences:
THY. A.0. Stewardess Licence issued on 11. 5. 72. Ffight time:
Grand total: 1,029 hours 55 minutes.
In the type of aircraft to which the accident occurred: 90 hours.
Stewardess: Miss Sibel Zahin (Turkish nationality)
Age: 22. Spinster.
Certificates and licence:
THY A.0. Stewardess Licence issued on 1 l. 5. 72.
Flight time:
Grand total: 1,262 hours 15 minutes.
In the type of aircraft to which the accident occured: 494 hours 50 minutes.
Stewardess: Miss Semra Hidir (Turkish nationality)
Age: 20. Spinster.
Certificates and licences:
THY A.0. Stewardess Licence issued on 2. 4. 73.
Fhght time:
Grand total: 741 hours 45 minutes.
In the type of aircraft to which the accident occurred: 74 hours 50 minutes.
Stewardess: Miss Fatma Barka (Turkish nationality)
Age: 25. Spinster.
Certificates and licences:
THY. A.0. Stewardess Licence issued on 8. 11. 71.
Flight time:
Grand total: 1,465 hours 50 minutes.
In the type of aircraft to which the accident occurred: 297 hours 40 minutes.
Stewardess: Miss Rona Altinay (Turkish nationality)
Age: 29. Spinster.
Certificates and licences:
THY A.0. Stewardess Licence issued on 11. 1. 67.
Flight time:
Grand total: 4,456 hours.
In the type of aircraft to which the accident occurred: 3S7 hours IS minutes.
Stewardess: Miss Ayse Birgili (Turkish nationality)
Age: 22. Spinster.
Certificates and licence:
THY A.0. Stewardess licence issued on 1. 9. 71.
Flight time:
Grand total: 1,723 hours l5 minutes.
In the type of aircraft to which the accident occurred: 139 hours 5 minutes.
Aircraft information passenger configuration
3
Aircraft information
3.6.1 Airframe
Owner and operator
Turk Hava YoBari A.0. (Turkish Airlines Inc)
Constructor
McDonnel Douglas Corporation
Type: DC-10-10
Maker’s Serial No: 46,704
Date of first flight: 27. 2.?2
Delivery date: 10. 12. 72.
Registration: TC-JAY
Certificate of Airworthiness and Certificate of Registration (combined in Turkey in the same document): No 342 dated 20. 12. 72 and valid (Certificate of Airworthiness) until 3. 12. 74.
Last inspection at Istanbul: 21. 1. 74 (Inspection Sc-4) Total flying time: since manufacture: 2,955 hours 52 minutes (in the aircraft log book); since the last periodic check: ‘C’ Check: 81 hours 34 minutes ‘D’ Check: 487 hours, 17 minutes.
Previous accidents: none.
3.6.2 Engines
Manufacture: General Electric Company
Type and power: CF6-6D
Maxim' take-off thrust: ll8,144 kg
Airframe position
(From left to right)
Maker serial number 451 - 215 Total operating time 2,358 hours
3.6.4 Weight distribution and centre of gravity
THY aircraft at Orly use Paris Airport services for what are known as the ‘Traffic’ operations which include the preparation of the load and trim sheets and the passenger manifests.
Weight
The initial Load Sheet was supplemented at the very last minute by the addition of 20 passengers. The part of the Load Sheet at the bottom left-hand side of the printed form was not changed accordingly. This shows a total passenger weight of 23,170 kg and a take-off weight of 16.1,628.kg;
The ‘Passengers’ item on the Load Sheet shows an entry of 306 adult passengers (male: 56 + 193; female: 57;) 6 children and l infant. The corresponding load of 23,170 kg was calculated as follows:
306 adult passengers x 75 kg = 22,950
06 children x 35 = 210
01 infant x 10 = 010
Total = 23,170
The“Last' Minute Changes’ item shows 20 additional passengers and a corresponding weight of 1',480 kg, ie s total of 333 passengers (326 adult passengers, 6 children and 1 infant) and a corresponding load of 24,650 kg. The distribution of these last minute 20 passengers among the passenger compartments was not shown on the Balance Sheet.
In view of the item ‘Last Minute Changes’, the crew could have calculated the actual take-off weight to be 163:,108 kg, as a result of the addition of the 20 extra passengers (1,480 kg).
The fact that the relevant take-off speeds used by the pilot were higher than those corres-pounding to the weight initially calculated, gives reason to suppose that the increase in the load was evaluated by the crew of TC-JAY.
Limitations applicable to DC-10-10 TC-JAY:
Maximum take-off weight:.195,000 kg
Maximum landing weight: 164,890 kg
Maximum zero fuel weight: 151,950 kg.
On the day of the Fight, the maximum take-off weight permitted under the limitations (landing limitation) was 172,600 kg (164,890 kg + estimated fuel consumption of 7,710 kg = 172,600 kg). The actual take-off weight of 163,178 kg was within the required limitation for the flight in question. In considering whether the centre of gravity-position of TC-JA'V for flight TK 981 was within the appropriate limits, a judgment can be formed on the beds of: the Flight Manual, section 1, page 4-1 (approved by the F.A.A.)", the TtlY Balance Sheet used by traffic staff. for the planned and the actual zero fuel weights of 135,318 kg and 136,798 kg respectively, the Manual prescribes a forward limit of 8% M.A.C.
The centre of gravity envelope is established in the Manual on the assumption of complete and accurate knowledge of the loads as regards both weight and location in the aircraft. The centre of gravity diagram established on the basis of a calculation for possible errors is more stringent and fixed the forward limit at 10.2% M.A&. The 11.3% position calculated for TC-JAV was therefore within the limits referred to above.
In the same way, the centre of gravity position for the take-off weight was 16.7%; it was therefore within the limit of 12.6% fixed by the Flight Manual
Freight and baggage In order to distribute the load among the three cargo compartments of the DC-IO-1O, the traffic officers had to take into account the following considerations:
The forward cargo compartment had been loaded at Istanbul with 2,S96 kg of freight and baggage destined for London.
The four containers loaded with 1,525 kg of baggage at Orly could be placed only in the central or forward compartments as the aft cargo compartment was kept for bulk cargo. There was no freight of this type for flight TK 981 on departure from Orly on 3 March. The four containers with 1,525 kg of baggage ware placed in the central compartment. During the short stop at Orly, there was no reason connected with the centre of gravity position to transfer to the central compartment the containers loaded into the forward compartment at Istanbul.
Passengers
The planned distribution of passengers among the three cabin compartments at the time of completion of the Load and Trim Sheet was as follows: compartment 1 (forward) compartment 2 compartment 3 (rear) (capacity: 86 passengers): 76 (capacity: 108 passengers): 98 (capacity: 151 passengers): 140 ie a total of 314 passengers as shown on the diagram on the right-hand side of the form used.
Hypotheses regrading the variation in the calculated position of the centre of' gravity, as a function of: the presence of the last minute passengers; the fuel consumption between the time of takeoff and the time when failure of the airframe occurred; the loss of persons and parts of the aircraft during flight, Number of passengers on,hoed: 332 adults and children+ l infant. Passengers regarded as a causal factor in a possible chancre in the centre of gravity position: 18 (excluding 1 infant).
Recapitulation
Forward centre of gravity limit for zero fuel weight. Forward centre of gravity limit for weight with fuel on board
FAA Approved Airplane Flight Manual'. 8% M.A.C. – Centre of gravity diagram: 10% M.A.C. FAA Approved Airplane Flight Manual: 12% M.A.C;
First possibility (less favourable): The 38 passengers were. distributed between compartments 1 and 2:
Compartment 1: Compartment 2: Compartment 3;
86 passengers (+ 10)
166 passengers-(+ 8)
140 passengers (no change).
Fuel consumption estimated at 2,060 kg, corresponding to about 24,000 kg of fuel on board at the time of depressurization.
Centre of gravity position for zero fuel: Centre of gravity position (on depressurization):
9% M.WC. 15% M.A.C. Centre of gravity position after the loss in flight of passengers and aircraft structure (about 500 kg) 14% M.A.C.
For the zero fuel weight: centre of gravity position within the forward limit according to the Flight Manual centre of.gravity position outside the forward limit by 1%, according to the diagram. For the weight with fuel: centre of gravity position always within the forward limit.
Second possibility: The 18 Passengers were distributed among compartments 2 and 3:
Compartment 1: Compartment 2: Compartment 3:
76 passengers (no change)
105 passengers(+ 7)
151 passengers (+ 11).
Centre of gravity position for zero fuel: Centre of gravity position on depressurization: 11.6% M.A.C. 16.8% M.A.C. Centre of gravity position after the loss of weight from the rear of the aircraft: 16.0% M.A.C.
Conclusions
In both cases the centre of gravity position remains within the normal limits.The possibility of movement of passengers forward as a result of panic on the collapse of the floor cannot be regarded as a possible hazard for the centre of gravity position. In the less favorable of the above two hypotheses, at least 50 passengers would have had to move in order to bring the centre of gravity position to its forward limit with fuel.
Although the distribution:of the 332 persons over the 34S cabin seats is not known, centre of gravity problems cannot be regarded as factors aggravating the situation which occurred as a result of the ejection of the aft cargo door.
Aircraft information
3.6.1 Airframe
Owner and operator
Turk Hava YoBari A.0. (Turkish Airlines Inc)
Constructor
McDonnel Douglas Corporation
Type: DC-10-10
Maker’s Serial No: 46,704
Date of first flight: 27. 2.?2
Delivery date: 10. 12. 72.
Registration: TC-JAY
Certificate of Airworthiness and Certificate of Registration (combined in Turkey in the same document): No 342 dated 20. 12. 72 and valid (Certificate of Airworthiness) until 3. 12. 74.
Last inspection at Istanbul: 21. 1. 74 (Inspection Sc-4) Total flying time: since manufacture: 2,955 hours 52 minutes (in the aircraft log book); since the last periodic check: ‘C’ Check: 81 hours 34 minutes ‘D’ Check: 487 hours, 17 minutes.
Previous accidents: none.
3.6.2 Engines
Manufacture: General Electric Company
Type and power: CF6-6D
Maxim' take-off thrust: ll8,144 kg
Airframe position
(From left to right)
Maker serial number 451 - 215 Total operating time 2,358 hours
3.6.4 Weight distribution and centre of gravity
THY aircraft at Orly use Paris Airport services for what are known as the ‘Traffic’ operations which include the preparation of the load and trim sheets and the passenger manifests.
Weight
The initial Load Sheet was supplemented at the very last minute by the addition of 20 passengers. The part of the Load Sheet at the bottom left-hand side of the printed form was not changed accordingly. This shows a total passenger weight of 23,170 kg and a take-off weight of 16.1,628.kg;
The ‘Passengers’ item on the Load Sheet shows an entry of 306 adult passengers (male: 56 + 193; female: 57;) 6 children and l infant. The corresponding load of 23,170 kg was calculated as follows:
306 adult passengers x 75 kg = 22,950
06 children x 35 = 210
01 infant x 10 = 010
Total = 23,170
The“Last' Minute Changes’ item shows 20 additional passengers and a corresponding weight of 1',480 kg, ie s total of 333 passengers (326 adult passengers, 6 children and 1 infant) and a corresponding load of 24,650 kg. The distribution of these last minute 20 passengers among the passenger compartments was not shown on the Balance Sheet.
In view of the item ‘Last Minute Changes’, the crew could have calculated the actual take-off weight to be 163:,108 kg, as a result of the addition of the 20 extra passengers (1,480 kg).
The fact that the relevant take-off speeds used by the pilot were higher than those corres-pounding to the weight initially calculated, gives reason to suppose that the increase in the load was evaluated by the crew of TC-JAY.
Limitations applicable to DC-10-10 TC-JAY:
Maximum take-off weight:.195,000 kg
Maximum landing weight: 164,890 kg
Maximum zero fuel weight: 151,950 kg.
On the day of the Fight, the maximum take-off weight permitted under the limitations (landing limitation) was 172,600 kg (164,890 kg + estimated fuel consumption of 7,710 kg = 172,600 kg). The actual take-off weight of 163,178 kg was within the required limitation for the flight in question. In considering whether the centre of gravity-position of TC-JA'V for flight TK 981 was within the appropriate limits, a judgment can be formed on the beds of: the Flight Manual, section 1, page 4-1 (approved by the F.A.A.)", the TtlY Balance Sheet used by traffic staff. for the planned and the actual zero fuel weights of 135,318 kg and 136,798 kg respectively, the Manual prescribes a forward limit of 8% M.A.C.
The centre of gravity envelope is established in the Manual on the assumption of complete and accurate knowledge of the loads as regards both weight and location in the aircraft. The centre of gravity diagram established on the basis of a calculation for possible errors is more stringent and fixed the forward limit at 10.2% M.A&. The 11.3% position calculated for TC-JAV was therefore within the limits referred to above.
In the same way, the centre of gravity position for the take-off weight was 16.7%; it was therefore within the limit of 12.6% fixed by the Flight Manual
Freight and baggage In order to distribute the load among the three cargo compartments of the DC-IO-1O, the traffic officers had to take into account the following considerations:
The forward cargo compartment had been loaded at Istanbul with 2,S96 kg of freight and baggage destined for London.
The four containers loaded with 1,525 kg of baggage at Orly could be placed only in the central or forward compartments as the aft cargo compartment was kept for bulk cargo. There was no freight of this type for flight TK 981 on departure from Orly on 3 March. The four containers with 1,525 kg of baggage ware placed in the central compartment. During the short stop at Orly, there was no reason connected with the centre of gravity position to transfer to the central compartment the containers loaded into the forward compartment at Istanbul.
Passengers
The planned distribution of passengers among the three cabin compartments at the time of completion of the Load and Trim Sheet was as follows: compartment 1 (forward) compartment 2 compartment 3 (rear) (capacity: 86 passengers): 76 (capacity: 108 passengers): 98 (capacity: 151 passengers): 140 ie a total of 314 passengers as shown on the diagram on the right-hand side of the form used.
Hypotheses regrading the variation in the calculated position of the centre of' gravity, as a function of: the presence of the last minute passengers; the fuel consumption between the time of takeoff and the time when failure of the airframe occurred; the loss of persons and parts of the aircraft during flight, Number of passengers on,hoed: 332 adults and children+ l infant. Passengers regarded as a causal factor in a possible chancre in the centre of gravity position: 18 (excluding 1 infant).
Recapitulation
Forward centre of gravity limit for zero fuel weight. Forward centre of gravity limit for weight with fuel on board
FAA Approved Airplane Flight Manual'. 8% M.A.C. – Centre of gravity diagram: 10% M.A.C. FAA Approved Airplane Flight Manual: 12% M.A.C;
First possibility (less favourable): The 38 passengers were. distributed between compartments 1 and 2:
Compartment 1: Compartment 2: Compartment 3;
86 passengers (+ 10)
166 passengers-(+ 8)
140 passengers (no change).
Fuel consumption estimated at 2,060 kg, corresponding to about 24,000 kg of fuel on board at the time of depressurization.
Centre of gravity position for zero fuel: Centre of gravity position (on depressurization):
9% M.WC. 15% M.A.C. Centre of gravity position after the loss in flight of passengers and aircraft structure (about 500 kg) 14% M.A.C.
For the zero fuel weight: centre of gravity position within the forward limit according to the Flight Manual centre of.gravity position outside the forward limit by 1%, according to the diagram. For the weight with fuel: centre of gravity position always within the forward limit.
Second possibility: The 18 Passengers were distributed among compartments 2 and 3:
Compartment 1: Compartment 2: Compartment 3:
76 passengers (no change)
105 passengers(+ 7)
151 passengers (+ 11).
Centre of gravity position for zero fuel: Centre of gravity position on depressurization: 11.6% M.A.C. 16.8% M.A.C. Centre of gravity position after the loss of weight from the rear of the aircraft: 16.0% M.A.C.
Conclusions
In both cases the centre of gravity position remains within the normal limits.The possibility of movement of passengers forward as a result of panic on the collapse of the floor cannot be regarded as a possible hazard for the centre of gravity position. In the less favorable of the above two hypotheses, at least 50 passengers would have had to move in order to bring the centre of gravity position to its forward limit with fuel.
Although the distribution:of the 332 persons over the 34S cabin seats is not known, centre of gravity problems cannot be regarded as factors aggravating the situation which occurred as a result of the ejection of the aft cargo door.
Voice recorder and Accident
4
Cockpit voice recorder
In accordance with national and international requirements, TC-JAV was equipped with a cockpit voice recorder (CVR), type Collins, model 642 C-1. The cockpit voice recorder was located alongside the flight data recorder, inside the aft cargo compartment and immediately to the rear of the aft cargo door on the left and side.
The CVR was found about l50 metres beyond the initial point of impact in the forest of Ermenonville and was considerably damaged, but the recording could still be heard. It was first played beck and copies made at the French Air Navigation Technical Service, in the presence of French and foreign experts of the Commission of Inquiry.
Appended is the transcript of this recording; the times were established in agreement with the time tracks of the communications between the aircraft and the central services (Airport and ACC North).
'It should be noted that the time which elapsed, seventy«seven seconds, between tho noise of decompression and the end of the CVR recording is practically identical with that measured on the flight data recorder. Nevertheless, for the period in question there is a time shift of the order of thirty seconds between the time supplied by the flight data recorder (indication taken from the clock of the flight engineer’s pane1) and the time common to the ACC/Tower/CVR (ACC time = flight data recorder time minus 30 seconds). With allowance for the various factors available for the purposes of comparison, this discrepancy appears to be approximately constant and of the same magnitude throughout
the flight.
In addition to the information provided by the communications recorde4 on the ground and the various observations entered on the transcript appended, the CVR recording reveals in particular the following points during the 1ast phase of the fight:-
Decompression heard at 113956 hrs.
Pressurization warning heard almost immediately and for slightly less than 25 seconds.
Identification of the nature of the accident by the crew.
Overspeed warning heard at about 114023 hrs, probably untii the end of the record-ing (although very faint during the last moments) ie for 50 seconds.
CVR recording stopped at 114113 hrs.
Flight data recording
In accordance to the national and international requirements, TC-JAV was equipped with a flight data recorder, type Sunstrand Data Control, model 573 A, maker’s serial number 2104, located under the floor on the left-hand side, alongside the cockpit voice recorder and immediate1y to the rear of the aft cargo door on the left-hand side.
The fight data recorder was found in the area of the main wreckage, about 60D m 5om the initial point of impact. The outer case was substantially damaged on impact (no trace of fire or smoke); the vicaUoy magnetic tape was very dirty, bent and broken in two places. The recorder was taken to the USA where the NTSB arranged for the tape to be read out at the premises of the firms of Sunstrand and Teledyne, in the presence of French experts from Bretigny Flight Test Centre and the 'Accidents Investigation Bureau. The read-out was established in graphical form and subsequently a fresh read-out was made at the Brbtigny Flight Test Centre on the RESEDA installation, using the calibrations established for the KSSU group. The results obtained were in agreement.
Appended are graphs showing the variations in the parameters during the flight and the accident.
The principal points regarding the read-out may be surmised as follows:
Take-off: 1131 hrs (flight data recorder time).
Takeoff was made with reduced thrust, rotation began at 143 knots, ie 4 knots below the predetermined V2, and the ground roB time was of the order of 40 seconds.
During the takeoff, the horizontal stabilizer setting was about -6%º, the maximum attitude reached was 19', while the elevator angle changed progressively from 8º to l 1º.
Climb: 1132 hrs to 1.139 hrs (flight data recorder time).
The climb progressed normally. It should be noted that there was a stretch of level flight at 6,000 feet for more than two minutes (l135 hrs to 1136 hrs). Shortly before reaching 12,000 feet, the aircraft climbed at 300 knots indicated air speed with a rate of climb of 2,200 feet a minute. The attitude was of the order of 3', the horizontal stabilizer was set at ¿A' nose-up and the elevators were 2º to 3º aircraft nose-up.
Accident:
It can be deduced that pressurization occurred at 114026 hrs at about 11,500 feet. Two seconds later the following conditions were found:
An angle of some 10º, to the left of the two rudder control surfaces; the change in heading to the left was 9º.
A nose-down movement of the elevator surfaces of which the angle had decreased by about 3º, while the aircraft’s attitude decreased accordingly.
The horizontal stabilizer angle recorded changed from ’hº nose-up to 6Viº nose-down.
The speed of No 2 engine had fallen to 459o by 114029 hrs.
(Only one item of this information is aberrant, that relating to the setting of the horizontal stabilizer, limited by a mechanical stop to an angle smaller than that recorded after the depressurization. In addition, the horizontal stabilizer cannot move so swiftly and a change in angle as large as that recorded would inevitably have given rise to far larger vertical accelerations than those recorded. The transducer of the movement of the stabilizer is in a forward position in the aircraft, on the cable which transmits this information to the cockpit, and it is more than likely that the doubtful value recorded corresponds to tension of this cable, associated with the damage to the floor.)
The aircraft nose-down attitude became rapidly steeper, -20º was reached 22 seconds after decompression and simultaneously the speed increased to 362 knots, although Nos 1 and 3 engines had been throttled back.
At the end of minute 1140 hrs, the speed reached 400 knots at 7,200 feet, the ailerons seemed to function correctly and the angle of bank to the left did not exceed 20º.
At the beginning of minute 1141 hrs, the attitude began to decrease progressively and the speed to stabilise around 430 knots without this appearing to be due to the control surfaces.
Impact occurred at 114143 hrs (flight data recorder time) at an attitude of -4º, a speed of 423 knots and on a heading of 281º.
Wreckage
Main wreckage
The DC-10 made impact with the ground in the department of Oise at a place called ‘Le Bosquet de Dammartin’ in the commune of Fontaine ChaaUs.
The accident site is located in a small enclosed valley, running from east to west and covered with Scotch and maritime pines. The ground is rugged with some rock outcrops on the east side. The average elevation is 105 metres. The area affected by the aircraft impact exceeded 65,000 square metres. The aircraft literally disintegrated into fragmented wreckage. It cut a swath through the forest some 700 metres long by 100 metres wide.
On the initial impact with the tops of trees about 10 metres high, the aircraft was on a heading of 280º, with a pitch attitude close to -4º and an angle of bank to the left of the order of 17º. This information has been obtained from the flight data recording and inspection of the site, both of which gave the same indications. The very high speed was between 420 and 430 knots (800 km/hr).
If this initial impact on the edge of the ‘des Epines’ forest road is taken as the point of origin for the measurement of distance on the wreckage trail, it becomes evident that in the violence of the impact the airframe was completely shattered. The wreckage recovered came from both forward and rear parts of the aircraft structure.
Impact with the gr6und was made about 330 metres away from the initial 'point of impact. Along this distance of 330 metres the aircraft cut through hundreds of trees. Wreckage of the wings and the frames of the forward doors was found along a trail 100 to 150 meties wide. At a point about 220 metres along and 60 metres south of the centre line of the swath, the cockpit voice recorder was found it had been installed in the rear part of the aircraft on the left-hand side, below the leading edge of the vertical stabilizer.
Between 170 and 270 metres along the wreckage trail, traces of kerosene were found along both the north and south edges of the va11ey, providing evidence of 'the points where the fuel tanks broke up. Wreckage of No 3 engine was also found on the north side of the area devastated by the aircraft
Between 250 and ‘270 metres, along this same north side, numerous small pieces of wreck-age were found, mainly of the wings and the engines. The airframe touched the ground at a point between 330 and 440 metres along the trail. A violent explosion ensued and the practical disintegration of the aircraft. In this area, numerous small fragments from all parts of the aircraft were found intermingled.
From 400 to 600 metres, various pieces of wreckage, generally small in size, were found scatted over the whole width of' the crash area. The flight data recorder was found at the left-hand edge of this ‘section of the trai1. At the end of this section there were two fairly large pieces of wreckage, the tail aft body and part of the fuselage with a door frame and nine windows.
No 2 engine was recovered at 650 m, on the ‘de la cavee road. This engine had remained sufficiently intact for its component parts to be examined.
The last wreckage eas found 700 metres fiom the initial point of impact.
Wreckage found at Saint-Pathus
On the morning of 4 March, French experts accompanied by police officers from Saint-Pathus found the bodies of six passengers, parts of the aircraft seats and the wreckage of the aft cargo door, beneath the aircraft’s flight path and 15 km before the main wreckage.
Aft cargo door on the left-hand side
The wreckage of this door was composed of:
The lower part of the door with the 4 latches and their complete control and locking mechanism, and a1so the push rod controlling the lock tube.
The electric motor of the latch actuator was not found.
Part of the door including the locking handle with the link and the vent door shaft and also the detached tap fitting of the push rod.
The vent door was not found. The cargo door operating arm.
All these parts came down in free fall into newly ploughed fields and were embedded in the fairly soft earth so that they were little damaged on impact with the ground; any fractures occurred on ejection from the aircraft.
A visual inspection of the wreckage was carried out immediately at the sites where it was found, with the following results:
absence of any marks of fire or over-heating,
incomplete closing of the door latches;
non-engagement of the lock-pins;
the electric motor of the latch actuator had become detached from its mounting and was not found;
the handle was out of its housing (open position); the trigger whicb retains. it in its housing had been forced and was difficult to work;
the links controlling the latch had not reached over-centre and any slight force exerted on the latches caused displacement of the actuator assembly of which the upper part was no longer fixed positively to the door structure.
All these parts were then taken to Le Bourget and subsequently to Saclay Tqst Centre for more detailed laboratory examination.
Identification of the door
Two references were ink-stamped on the door in two different places:
First reference: P/N NFA 6070-501 N
S/N 46704/11 FG401
Second reference: P/N NFA 6070-507
The following indications were inscribed under the reference:
F/N EDITION PROD INSP ACCEPT
29 1 058D4 ZAI 04
The document DOUGLAS NFA 6070 ‘W’ confirmed the door reference of NFA 6070-507 (the vent door installation had caused the reference to be changed from 501 to 507).
Principal findings of the examination of the door wreckage
On the instruction plate for manual opening of the latch actuator, there was a hole, 28 not prescribed by. Douglas and driRed by THY, in order to gain direct access to the drive mechanism (incorrect exeeution of SB 52-3S).
The link (LINK ASSY P/N ADA 7366-501), between the locking handle and the vent door. shaft, was bent
The additional support plate specified for the vent door shaft by SB 52-37: had not been installed‘.
The push rod (LINK ASSY P/N ADA 7372), between the vent door shaft and the lock tube, was. beat and the two crank attachment rivets were sheared. ‘
The forward bottom structural corner of the door was deformed. This damage, due to contact with the ground after a fall of 3,600 metres, had caused slight deformation of the Iock tube and the mounting of the lock limit switch.
The end of the lock tube was chamfered as prescribed by SS 52-37. Rough file marks and irregular scoring showed that this work was done man
The stricker of-the unlock switch had two DOUGLAS P/N A'FA 3210-1 shims, surmounted by a third shim with no reference number consisting thin crumpled piece of metal leaf with numerous folds on the side on the side which had to come up against the roller of the unlock limit switch. The presence of this part, unusual in equipment to aeronautical standards, was surprising and could only have entailed imprecision and erratic functioning of this switch which closes the circuit to the latch actuator in the sense of opening the latches only. This defective installation had no effect on safety but could have been the source of numerous difficulties in opening the door.
Medica1 and pathological information
It had already been decided on the day after the accident to take the remains of the ’ passengers and crew members to the Institute Miedico-Legal de Paris, for the purpose of. the Inquiry.
In view of the exceptionally large number of victims t4e medical team encountered difficulties, as the institute did not have facilities on a scale related to this type of accident.
The results of the examination of the bodies of the victims were as follows:
Lesions observed
From the traumatological standpoint, the lesions could be classified into two categories:
(a) In the case of the bodies recovered at the main accident site in the forest of Ermenonville, there was a high degree of fragmentation (nearly 20,000 fragments were listed) associated with the violence of the impact.
(b) On the other hand, the six bodies found near Saint-Pathus were complete, although presenting fractures and serious visceral lesions. Careful examination showed:
that there were no external burns;
that there were no external lesions which could be associated with the projection of metal or other fragments as the result of an explosion caused either by a criminal act or otherwise;
by X-ray examination, that there was no evidence of deep penetration by metal fragments.
Toxicological examination
Routine toxicological examinations were made of the six bodies recovered over Saint-Pathus and of a number of fragments recovered at Ermenonville and selected at random. No evidence was detected of:
carbon monoxide;
cyanhydric derivatives;
chlorine derivatives;
alcohol.
Identification
188 bodies or parts of bodies were positively identified by the use of a number of techniques:
finger-printing (in particular in the case of Turkish and Japanese nationals, because of the existence of national finger-print records);
examination of teeth;
bone measurements;
clothing, personal effects.
It should be noted that finger-printing was of' great assistance and that the use of a computer proved to be essential for processing the enormous quantity of data required for identification purposes.
Fire:
The circumstances of the impact (disintegration at very high speed in the trees) were such that there was practically no fire, apart from a few very minor localised outbreaks where fires of short duration persisted for only a few moments.
Jet Al fuel was used and there were about 23,500 Btres on board at the time of impact.
Survival aspects – Rescue operations
Survival aspects
The accident occurred in two phases which left no chance of survival for the 346 occupants of the DC-10. The first phase occurred at 1140 hrs over the commune of Saint-Pathus, where six of the aircraft occupants were ejected at an altitude of about 3,600 metres.
The second phase was that of the impact at 1141 hrs, when the aircraft flew into the forest at a speed of 430 knots (800 km/hr), leaving no chanci of survival for its occupants.
Rescue operations
The Air Traffic Control was immediately aware of the loss of radio and radar contact and was able to locate the area of the accident, thereby simplifying the task of the alerting and search services (VHF caBs, to which no reply was received, from 114150 hrs to 114650 hrs; telephone enquiries in conjunction wiih Orly, Le Bourget and Creil, from 1144 hrs to 1238 hrs).
The rescue operation was already well under way when the DETRESFA message was transmitted by the North Area Control Centre at 1200 hrs and the presumption of accident message at 1240 lus.
After information had been obtained at the accident site, the accident notification message was transmitted at 1615 hrs and the DETRESFA termination message at 1650 hrs.
At 1840 hrs, Doullens Centre announced that the SAR operation had ended at 1732 hrs.
In addition to the occurrences recorded by the North Area Control Centre, the crash of the DC-10 was reported by 1145 hrs to the Senlis Gendarmerie Brigade by the Survilliers C.R.S. (riot police) Station (Val d’Oise). From 1145 hrs onwards, exceptionally large scale rescue facilities (air and ground) were put into operation by the civil and military authorities (police, armed forces, civil emergency centres, Paris Airport, etc).
Within a very short time, at 1215 hrs, the first rescue teams arrived at the site. The conveyance of the bodies of the victims to the church of Saint-Pierre de Senlis began at 1345 hrs.
The bodies recovered near the villages of Saint-Pathus and Oissery were taken to Meaux hospital.
Seventeen emergency centres (civil and military facilities) with fifty-six vehicles of various kinds were used and about three hundred persons took part in the operations on the first day.
Finally, the operations for the transfer of the aircraft wreckage began on 8 March and were completed on 20 March.
Cockpit voice recorder
In accordance with national and international requirements, TC-JAV was equipped with a cockpit voice recorder (CVR), type Collins, model 642 C-1. The cockpit voice recorder was located alongside the flight data recorder, inside the aft cargo compartment and immediately to the rear of the aft cargo door on the left and side.
The CVR was found about l50 metres beyond the initial point of impact in the forest of Ermenonville and was considerably damaged, but the recording could still be heard. It was first played beck and copies made at the French Air Navigation Technical Service, in the presence of French and foreign experts of the Commission of Inquiry.
Appended is the transcript of this recording; the times were established in agreement with the time tracks of the communications between the aircraft and the central services (Airport and ACC North).
'It should be noted that the time which elapsed, seventy«seven seconds, between tho noise of decompression and the end of the CVR recording is practically identical with that measured on the flight data recorder. Nevertheless, for the period in question there is a time shift of the order of thirty seconds between the time supplied by the flight data recorder (indication taken from the clock of the flight engineer’s pane1) and the time common to the ACC/Tower/CVR (ACC time = flight data recorder time minus 30 seconds). With allowance for the various factors available for the purposes of comparison, this discrepancy appears to be approximately constant and of the same magnitude throughout
the flight.
In addition to the information provided by the communications recorde4 on the ground and the various observations entered on the transcript appended, the CVR recording reveals in particular the following points during the 1ast phase of the fight:-
Decompression heard at 113956 hrs.
Pressurization warning heard almost immediately and for slightly less than 25 seconds.
Identification of the nature of the accident by the crew.
Overspeed warning heard at about 114023 hrs, probably untii the end of the record-ing (although very faint during the last moments) ie for 50 seconds.
CVR recording stopped at 114113 hrs.
Flight data recording
In accordance to the national and international requirements, TC-JAV was equipped with a flight data recorder, type Sunstrand Data Control, model 573 A, maker’s serial number 2104, located under the floor on the left-hand side, alongside the cockpit voice recorder and immediate1y to the rear of the aft cargo door on the left-hand side.
The fight data recorder was found in the area of the main wreckage, about 60D m 5om the initial point of impact. The outer case was substantially damaged on impact (no trace of fire or smoke); the vicaUoy magnetic tape was very dirty, bent and broken in two places. The recorder was taken to the USA where the NTSB arranged for the tape to be read out at the premises of the firms of Sunstrand and Teledyne, in the presence of French experts from Bretigny Flight Test Centre and the 'Accidents Investigation Bureau. The read-out was established in graphical form and subsequently a fresh read-out was made at the Brbtigny Flight Test Centre on the RESEDA installation, using the calibrations established for the KSSU group. The results obtained were in agreement.
Appended are graphs showing the variations in the parameters during the flight and the accident.
The principal points regarding the read-out may be surmised as follows:
Take-off: 1131 hrs (flight data recorder time).
Takeoff was made with reduced thrust, rotation began at 143 knots, ie 4 knots below the predetermined V2, and the ground roB time was of the order of 40 seconds.
During the takeoff, the horizontal stabilizer setting was about -6%º, the maximum attitude reached was 19', while the elevator angle changed progressively from 8º to l 1º.
Climb: 1132 hrs to 1.139 hrs (flight data recorder time).
The climb progressed normally. It should be noted that there was a stretch of level flight at 6,000 feet for more than two minutes (l135 hrs to 1136 hrs). Shortly before reaching 12,000 feet, the aircraft climbed at 300 knots indicated air speed with a rate of climb of 2,200 feet a minute. The attitude was of the order of 3', the horizontal stabilizer was set at ¿A' nose-up and the elevators were 2º to 3º aircraft nose-up.
Accident:
It can be deduced that pressurization occurred at 114026 hrs at about 11,500 feet. Two seconds later the following conditions were found:
An angle of some 10º, to the left of the two rudder control surfaces; the change in heading to the left was 9º.
A nose-down movement of the elevator surfaces of which the angle had decreased by about 3º, while the aircraft’s attitude decreased accordingly.
The horizontal stabilizer angle recorded changed from ’hº nose-up to 6Viº nose-down.
The speed of No 2 engine had fallen to 459o by 114029 hrs.
(Only one item of this information is aberrant, that relating to the setting of the horizontal stabilizer, limited by a mechanical stop to an angle smaller than that recorded after the depressurization. In addition, the horizontal stabilizer cannot move so swiftly and a change in angle as large as that recorded would inevitably have given rise to far larger vertical accelerations than those recorded. The transducer of the movement of the stabilizer is in a forward position in the aircraft, on the cable which transmits this information to the cockpit, and it is more than likely that the doubtful value recorded corresponds to tension of this cable, associated with the damage to the floor.)
The aircraft nose-down attitude became rapidly steeper, -20º was reached 22 seconds after decompression and simultaneously the speed increased to 362 knots, although Nos 1 and 3 engines had been throttled back.
At the end of minute 1140 hrs, the speed reached 400 knots at 7,200 feet, the ailerons seemed to function correctly and the angle of bank to the left did not exceed 20º.
At the beginning of minute 1141 hrs, the attitude began to decrease progressively and the speed to stabilise around 430 knots without this appearing to be due to the control surfaces.
Impact occurred at 114143 hrs (flight data recorder time) at an attitude of -4º, a speed of 423 knots and on a heading of 281º.
Wreckage
Main wreckage
The DC-10 made impact with the ground in the department of Oise at a place called ‘Le Bosquet de Dammartin’ in the commune of Fontaine ChaaUs.
The accident site is located in a small enclosed valley, running from east to west and covered with Scotch and maritime pines. The ground is rugged with some rock outcrops on the east side. The average elevation is 105 metres. The area affected by the aircraft impact exceeded 65,000 square metres. The aircraft literally disintegrated into fragmented wreckage. It cut a swath through the forest some 700 metres long by 100 metres wide.
On the initial impact with the tops of trees about 10 metres high, the aircraft was on a heading of 280º, with a pitch attitude close to -4º and an angle of bank to the left of the order of 17º. This information has been obtained from the flight data recording and inspection of the site, both of which gave the same indications. The very high speed was between 420 and 430 knots (800 km/hr).
If this initial impact on the edge of the ‘des Epines’ forest road is taken as the point of origin for the measurement of distance on the wreckage trail, it becomes evident that in the violence of the impact the airframe was completely shattered. The wreckage recovered came from both forward and rear parts of the aircraft structure.
Impact with the gr6und was made about 330 metres away from the initial 'point of impact. Along this distance of 330 metres the aircraft cut through hundreds of trees. Wreckage of the wings and the frames of the forward doors was found along a trail 100 to 150 meties wide. At a point about 220 metres along and 60 metres south of the centre line of the swath, the cockpit voice recorder was found it had been installed in the rear part of the aircraft on the left-hand side, below the leading edge of the vertical stabilizer.
Between 170 and 270 metres along the wreckage trail, traces of kerosene were found along both the north and south edges of the va11ey, providing evidence of 'the points where the fuel tanks broke up. Wreckage of No 3 engine was also found on the north side of the area devastated by the aircraft
Between 250 and ‘270 metres, along this same north side, numerous small pieces of wreck-age were found, mainly of the wings and the engines. The airframe touched the ground at a point between 330 and 440 metres along the trail. A violent explosion ensued and the practical disintegration of the aircraft. In this area, numerous small fragments from all parts of the aircraft were found intermingled.
From 400 to 600 metres, various pieces of wreckage, generally small in size, were found scatted over the whole width of' the crash area. The flight data recorder was found at the left-hand edge of this ‘section of the trai1. At the end of this section there were two fairly large pieces of wreckage, the tail aft body and part of the fuselage with a door frame and nine windows.
No 2 engine was recovered at 650 m, on the ‘de la cavee road. This engine had remained sufficiently intact for its component parts to be examined.
The last wreckage eas found 700 metres fiom the initial point of impact.
Wreckage found at Saint-Pathus
On the morning of 4 March, French experts accompanied by police officers from Saint-Pathus found the bodies of six passengers, parts of the aircraft seats and the wreckage of the aft cargo door, beneath the aircraft’s flight path and 15 km before the main wreckage.
Aft cargo door on the left-hand side
The wreckage of this door was composed of:
The lower part of the door with the 4 latches and their complete control and locking mechanism, and a1so the push rod controlling the lock tube.
The electric motor of the latch actuator was not found.
Part of the door including the locking handle with the link and the vent door shaft and also the detached tap fitting of the push rod.
The vent door was not found. The cargo door operating arm.
All these parts came down in free fall into newly ploughed fields and were embedded in the fairly soft earth so that they were little damaged on impact with the ground; any fractures occurred on ejection from the aircraft.
A visual inspection of the wreckage was carried out immediately at the sites where it was found, with the following results:
absence of any marks of fire or over-heating,
incomplete closing of the door latches;
non-engagement of the lock-pins;
the electric motor of the latch actuator had become detached from its mounting and was not found;
the handle was out of its housing (open position); the trigger whicb retains. it in its housing had been forced and was difficult to work;
the links controlling the latch had not reached over-centre and any slight force exerted on the latches caused displacement of the actuator assembly of which the upper part was no longer fixed positively to the door structure.
All these parts were then taken to Le Bourget and subsequently to Saclay Tqst Centre for more detailed laboratory examination.
Identification of the door
Two references were ink-stamped on the door in two different places:
First reference: P/N NFA 6070-501 N
S/N 46704/11 FG401
Second reference: P/N NFA 6070-507
The following indications were inscribed under the reference:
F/N EDITION PROD INSP ACCEPT
29 1 058D4 ZAI 04
The document DOUGLAS NFA 6070 ‘W’ confirmed the door reference of NFA 6070-507 (the vent door installation had caused the reference to be changed from 501 to 507).
Principal findings of the examination of the door wreckage
On the instruction plate for manual opening of the latch actuator, there was a hole, 28 not prescribed by. Douglas and driRed by THY, in order to gain direct access to the drive mechanism (incorrect exeeution of SB 52-3S).
The link (LINK ASSY P/N ADA 7366-501), between the locking handle and the vent door. shaft, was bent
The additional support plate specified for the vent door shaft by SB 52-37: had not been installed‘.
The push rod (LINK ASSY P/N ADA 7372), between the vent door shaft and the lock tube, was. beat and the two crank attachment rivets were sheared. ‘
The forward bottom structural corner of the door was deformed. This damage, due to contact with the ground after a fall of 3,600 metres, had caused slight deformation of the Iock tube and the mounting of the lock limit switch.
The end of the lock tube was chamfered as prescribed by SS 52-37. Rough file marks and irregular scoring showed that this work was done man
The stricker of-the unlock switch had two DOUGLAS P/N A'FA 3210-1 shims, surmounted by a third shim with no reference number consisting thin crumpled piece of metal leaf with numerous folds on the side on the side which had to come up against the roller of the unlock limit switch. The presence of this part, unusual in equipment to aeronautical standards, was surprising and could only have entailed imprecision and erratic functioning of this switch which closes the circuit to the latch actuator in the sense of opening the latches only. This defective installation had no effect on safety but could have been the source of numerous difficulties in opening the door.
Medica1 and pathological information
It had already been decided on the day after the accident to take the remains of the ’ passengers and crew members to the Institute Miedico-Legal de Paris, for the purpose of. the Inquiry.
In view of the exceptionally large number of victims t4e medical team encountered difficulties, as the institute did not have facilities on a scale related to this type of accident.
The results of the examination of the bodies of the victims were as follows:
Lesions observed
From the traumatological standpoint, the lesions could be classified into two categories:
(a) In the case of the bodies recovered at the main accident site in the forest of Ermenonville, there was a high degree of fragmentation (nearly 20,000 fragments were listed) associated with the violence of the impact.
(b) On the other hand, the six bodies found near Saint-Pathus were complete, although presenting fractures and serious visceral lesions. Careful examination showed:
that there were no external burns;
that there were no external lesions which could be associated with the projection of metal or other fragments as the result of an explosion caused either by a criminal act or otherwise;
by X-ray examination, that there was no evidence of deep penetration by metal fragments.
Toxicological examination
Routine toxicological examinations were made of the six bodies recovered over Saint-Pathus and of a number of fragments recovered at Ermenonville and selected at random. No evidence was detected of:
carbon monoxide;
cyanhydric derivatives;
chlorine derivatives;
alcohol.
Identification
188 bodies or parts of bodies were positively identified by the use of a number of techniques:
finger-printing (in particular in the case of Turkish and Japanese nationals, because of the existence of national finger-print records);
examination of teeth;
bone measurements;
clothing, personal effects.
It should be noted that finger-printing was of' great assistance and that the use of a computer proved to be essential for processing the enormous quantity of data required for identification purposes.
Fire:
The circumstances of the impact (disintegration at very high speed in the trees) were such that there was practically no fire, apart from a few very minor localised outbreaks where fires of short duration persisted for only a few moments.
Jet Al fuel was used and there were about 23,500 Btres on board at the time of impact.
Survival aspects – Rescue operations
Survival aspects
The accident occurred in two phases which left no chance of survival for the 346 occupants of the DC-10. The first phase occurred at 1140 hrs over the commune of Saint-Pathus, where six of the aircraft occupants were ejected at an altitude of about 3,600 metres.
The second phase was that of the impact at 1141 hrs, when the aircraft flew into the forest at a speed of 430 knots (800 km/hr), leaving no chanci of survival for its occupants.
Rescue operations
The Air Traffic Control was immediately aware of the loss of radio and radar contact and was able to locate the area of the accident, thereby simplifying the task of the alerting and search services (VHF caBs, to which no reply was received, from 114150 hrs to 114650 hrs; telephone enquiries in conjunction wiih Orly, Le Bourget and Creil, from 1144 hrs to 1238 hrs).
The rescue operation was already well under way when the DETRESFA message was transmitted by the North Area Control Centre at 1200 hrs and the presumption of accident message at 1240 lus.
After information had been obtained at the accident site, the accident notification message was transmitted at 1615 hrs and the DETRESFA termination message at 1650 hrs.
At 1840 hrs, Doullens Centre announced that the SAR operation had ended at 1732 hrs.
In addition to the occurrences recorded by the North Area Control Centre, the crash of the DC-10 was reported by 1145 hrs to the Senlis Gendarmerie Brigade by the Survilliers C.R.S. (riot police) Station (Val d’Oise). From 1145 hrs onwards, exceptionally large scale rescue facilities (air and ground) were put into operation by the civil and military authorities (police, armed forces, civil emergency centres, Paris Airport, etc).
Within a very short time, at 1215 hrs, the first rescue teams arrived at the site. The conveyance of the bodies of the victims to the church of Saint-Pierre de Senlis began at 1345 hrs.
The bodies recovered near the villages of Saint-Pathus and Oissery were taken to Meaux hospital.
Seventeen emergency centres (civil and military facilities) with fifty-six vehicles of various kinds were used and about three hundred persons took part in the operations on the first day.
Finally, the operations for the transfer of the aircraft wreckage began on 8 March and were completed on 20 March.
Engines and latch TC-JAV
5
Examination of No 2 engine
No 2 engine, General Blectric CF6-6D, serial number 451-200, was examined at the Centre d’essais des propulseurs de Sac1ay. It examination gave rise to the following conclusions:
the mechanical damage found on examination was due to the impact;
the engine was not lit at the time of impact;
the engine was running down at the time of impact;
there was no trace of fire.
Examination of the servo controls and of a horizontal stabilizer jackscrew
The sarvo controls (four for the elevator, two for the rudder and four for the ailerons) were recovered and found to be only very slightly damaged, they could therefore be examined.
The examination was made in the UTA hydraulics laboratories at Le Bourget. The electrical characteristics of the electro-hydraulic flow control valves were checked and no abnormality detected, either in the hydraulic part or in the electrical part.
An examination was also made of one of the two jackscrews for the control of the hori-zontal stabilizer; on this screw the nut was found to have jammed at the time of impact.
On examination of the jackscrew and its nut, the number of exposed threads between the bottom of the screw and the bottom of the nut could be measured. These measurements made only on this one screw gave for the stabilizer angle on impact a value very close to the position recorded before the loss of the door.
Examination of the latch actuator of the aft cargo door on the left-hand side
The irreversible actuator was taken off the door, The two bolts which attach the bracket on which it is mounted, were found sheared: the shearing force was estimated at 4,700 daN.
The shaft extension was 277.5 mm measured between the axis of the connection of the actuator to the structure and the axis at the end of the actuator ram (where it is con-nected to the torque tube). Normal extension required for correct closing of the latches is 297 mm.
COCKPIT CALL SYSTEM SWITCH: Satisfactory functioning
UNLOCK LIM1T SWITCH: Satisfactory functioning
CLOSE LIMIT SWITCH: Satisfactory functioning
LOCK LIMIT WARNING SWITCH: Did not function (arm distorted)‘
3.16.5 Check of the adjustment of the locking system
(a) Lock 5mit warning switch
The following repairs were made to the wreckage of the door:
straightening of the lock tube;
straightening and putting back into position the mounting of the lock limit warning switch;
replacement of the lock limit warning switch damaged during the crash, by a new switch of the same type.
After re-assembly of the parts, the following observations were made:
The striker P/N 7797-3 located at the end of the lock tube had ten shims, ie:
1 S4im PlN ADA 7773-1
8 shims P7N ADA 7773-50l
1 shim Pft4 ADA 7773-503
with a total thickness of 15.9 mm.
When the lock tube was pushed towards the locked position, the switch switched off the flight deck warning light, although the ends of the lock pins were still 3 millimetres away from the restraining flanges (fig 3). It should be noted, moreover, that according to the Maintenance Manual, the ends of the lock pins in the unlocked position must not be more than 2 mm away from the flanges.
In conclusion, the adjustment of the lock limit warning switch was defective and caused the flight deck warning light to go out when the latches were not necessary dosed.
(b) Adjustment of the lock tube
The two rods of adjustable 1ength by means of which the extreme positions.of the lock tube can be varied were straightened and their adjustments measured (the lockwire locking the adjustment nuts had remained in position).
The adjustments were as follows:
link P/N ADA 7366: distance between centres = 302.79 mm push rod P/N ADA 7372: distance between centres: 914.38 mm
These adjustments were then made to the corresponding rods on a door of the same type loaned by McDonnel Douglas, from which the support plate specified by SB 52-37 had been removed, thus making it conform to the definition of the door with which TC-JAV was equipped.
Tests on u door with the same definition as that of TCJAV
The results of examination of this door adjusted as describe above in accordance with the measurements made on the wreckage were as follows:
(1) Latches dosed, locking handle dosed
The four lock pins were engaged behind the restraining flanges and prevented the opening of the latches, but they were only partly engaged. The ends of the 1ock pins were 1.6 mm short of the rear face of the flanges (fig 4).
The official adjustment documentation – Maintenance Manual, Revision 4, January 1973 – stipulates that the ends of the lock pins, in the locked position, must protrude for
6.35 mm beyond the rear face of the flanges (fig 5).
In consequence, with this adjustment the lock tube in its locked position was 6.35 + 1.6 = 7.95 mm short of the correct locked position.
(2) Latches open
When the latches were open, the movement of the handle towards the closed position WR8 stopped when the lock pins came up against the front faces of the flanges.
Tests carried out on the same door, with varying adjustments of the extreme positions of the lock pins, showed that the force which has to be applied to the handle in order to force its closure depends on the extreme position (locked) to which the lock tube is adjusted.
When this adjustment is in accordance with the manufacture a requirement, ie when the ends of the lock pins protrude for 6.35 mm beyond the rear faces of the flanjges, it is physically impossible to force the handle even in the absence of the support plate for the vent door shaft (SB 52-3?).
On the other hand, when this distance of 6.35 mm is decreased, the force required fer forced closure also decreases. It becomes theoretically rdl when the end of the lock pin is in line with the front face of the flange.
During the tests carried out (with the lock tube adjustment 7.95 mm short of the correct position) the handle could therefore be closed (and the vent door apparently closed) with a force of 22 daN (about 50 1bs) (fig 7),
This closure was possible only because of deformation of the mechanism providing control transmission for the operation of the lock tube. The principal deformation affected the vent door shaft. The additional support plate specified by gR 52-37 (fig 6) was designed precisely to prevent 'such deformation.
It should be noted that the partial engagement of the lock pins as reproduced on the new door corresponds to the friction marks which they made on the edges of the es of the door of TC-JAV, which occurred only on the leading half of the edges (fig 8).
Conclusions:
The new door
Because of the defective adjustment of the extreme positions of the lock tube, the handle could be closed without excessive force, although the 3atches were not completely closed.
Defective closure could not be detected from the external appearance of the handle, vent
door and cargo door, unless a visual inspection was made through the view port provided
for that purpose.
Door of TC-JAV
The thickness of the striker shims made any correct adjustment of the lock pins impossible; any attempt to bring the ends of the lock pins to the correct distance of 6.35 mm beyond the rear face of the flanges inevitably led to damage to the lock limit warning switch.
The incorrect adjustment of this switch caused the flight deck warning light to go out when the door was still unlocked.
Because of the insufficient protrusion of the lock pins, the locking handle and vent door could be closed without excessive force, although the lock pins were stopped by the front face of the flanges (fig 7).
From the production and inspection documents received by the National Transportation Safety Board from Dougias, the aircraft manufacturer, it appears that the adjustments of the lock pins on fuselage Ho 29 (TC-JAV) gave a minimum pin protrusion of 0,25 inches (6.35 mm), account being taken of the accomplishment and verification of the work specified in EO ADA 7797 Change A.
These documents merely provide guarantees in accordance with prescribed forms, but the adjustments in question were also those shown in the Maintenance Manual (in particular
Revision 4, January 1973) and had to be verified or applied again by the operat.or when-ever any work was carried out on the door.
In brief, examination of the wreckage of the door of TC-JAV revealed defective adjustment of the lock limit warning switch. In addition, after the rods of a new door of the same definition had been adjusted to the dimensions measured on TC-JAV, it could be judged that the adjustment of the lock pins was likewise incorrect in the locked position.
The adjustment reconstructed in this way is consistent with that of the lock limit warning switch and also with the friction and other marks found an the lock pins and flanges. Finally, it provides an explanation of why the locking handle could be operated without excessive force although the latches were not fully engaged.
3.16.7 Research: accident on 12 June 1972 to DC-10-10, N 103AA near Windsor, (Ontario)
In the course of its work, the Commission of Inquiry studied the report of the National Transportation Safety Board, dated 28 February 1973, relating to the loss in flight of a similar aft cargo door on the left-hand side from an American Airlines DC-10-10.
Although the course of events and some of the causes are not exactly the same, nevertheless that accident presents points in common with the accident to TC-JAV:
The latches were not fully closed and the latch lock pins were not in place.
The flight deck warning light had gone out before effective locking had occurred.
The altitude reached by the American Airlines DC-10 was of the same order as that of TC-JAV when the door opened and the two bolts (connecting the fixed part of the latch actuator to the door structure) failed under the same conditions.
In the absence of pressure relief vents of adequate size between the passenger cabin and the aft cargo compartment, the sudden decompression in the cargo compartment caused damage to the cabin floor and its structure. This damage was less severe than in the case of TC-JAV in which the floor was more heavily loaded, but the functioning of the control cables was impaired in various ways, although it did not become completely impossible to control the aircraft.
In the conclusions of the NTSB report, it is stated that the probable cause of the accident
was the incorrect engagement of the latching mechanism and the design characteristics of
the system which permitted the door to be apparently dosed when the latches were not
fully engaged and the lock pins were not in place. Two recommendations had been issued
by the investigators:
modification to the locking system to make it physically impossible to position the external locking handle and vent door to their normal door-locked positions unless the lock pins are fully engaged;
the installation of pressure relief vents between the cabin and the aft cargo compartment to minimize the pressure loading on the cabin flooring in the event of sudden depressurization of the cargo compartment.
The first of these recommendations had given rise to the modifications specified in Alert Service Bulletin 52-35 and in Service Bulletins 52-27 and 52-37 (in the case of 52-37, only a start had been made with its application to TC-JAV).
Other modifications of the door closing system and methods of mitigating the effects of sudden depressurization of the aft cargo compartment were still under study at the time of the accident to TC-JAV.
Examination of No 2 engine
No 2 engine, General Blectric CF6-6D, serial number 451-200, was examined at the Centre d’essais des propulseurs de Sac1ay. It examination gave rise to the following conclusions:
the mechanical damage found on examination was due to the impact;
the engine was not lit at the time of impact;
the engine was running down at the time of impact;
there was no trace of fire.
Examination of the servo controls and of a horizontal stabilizer jackscrew
The sarvo controls (four for the elevator, two for the rudder and four for the ailerons) were recovered and found to be only very slightly damaged, they could therefore be examined.
The examination was made in the UTA hydraulics laboratories at Le Bourget. The electrical characteristics of the electro-hydraulic flow control valves were checked and no abnormality detected, either in the hydraulic part or in the electrical part.
An examination was also made of one of the two jackscrews for the control of the hori-zontal stabilizer; on this screw the nut was found to have jammed at the time of impact.
On examination of the jackscrew and its nut, the number of exposed threads between the bottom of the screw and the bottom of the nut could be measured. These measurements made only on this one screw gave for the stabilizer angle on impact a value very close to the position recorded before the loss of the door.
Examination of the latch actuator of the aft cargo door on the left-hand side
The irreversible actuator was taken off the door, The two bolts which attach the bracket on which it is mounted, were found sheared: the shearing force was estimated at 4,700 daN.
The shaft extension was 277.5 mm measured between the axis of the connection of the actuator to the structure and the axis at the end of the actuator ram (where it is con-nected to the torque tube). Normal extension required for correct closing of the latches is 297 mm.
COCKPIT CALL SYSTEM SWITCH: Satisfactory functioning
UNLOCK LIM1T SWITCH: Satisfactory functioning
CLOSE LIMIT SWITCH: Satisfactory functioning
LOCK LIMIT WARNING SWITCH: Did not function (arm distorted)‘
3.16.5 Check of the adjustment of the locking system
(a) Lock 5mit warning switch
The following repairs were made to the wreckage of the door:
straightening of the lock tube;
straightening and putting back into position the mounting of the lock limit warning switch;
replacement of the lock limit warning switch damaged during the crash, by a new switch of the same type.
After re-assembly of the parts, the following observations were made:
The striker P/N 7797-3 located at the end of the lock tube had ten shims, ie:
1 S4im PlN ADA 7773-1
8 shims P7N ADA 7773-50l
1 shim Pft4 ADA 7773-503
with a total thickness of 15.9 mm.
When the lock tube was pushed towards the locked position, the switch switched off the flight deck warning light, although the ends of the lock pins were still 3 millimetres away from the restraining flanges (fig 3). It should be noted, moreover, that according to the Maintenance Manual, the ends of the lock pins in the unlocked position must not be more than 2 mm away from the flanges.
In conclusion, the adjustment of the lock limit warning switch was defective and caused the flight deck warning light to go out when the latches were not necessary dosed.
(b) Adjustment of the lock tube
The two rods of adjustable 1ength by means of which the extreme positions.of the lock tube can be varied were straightened and their adjustments measured (the lockwire locking the adjustment nuts had remained in position).
The adjustments were as follows:
link P/N ADA 7366: distance between centres = 302.79 mm push rod P/N ADA 7372: distance between centres: 914.38 mm
These adjustments were then made to the corresponding rods on a door of the same type loaned by McDonnel Douglas, from which the support plate specified by SB 52-37 had been removed, thus making it conform to the definition of the door with which TC-JAV was equipped.
Tests on u door with the same definition as that of TCJAV
The results of examination of this door adjusted as describe above in accordance with the measurements made on the wreckage were as follows:
(1) Latches dosed, locking handle dosed
The four lock pins were engaged behind the restraining flanges and prevented the opening of the latches, but they were only partly engaged. The ends of the 1ock pins were 1.6 mm short of the rear face of the flanges (fig 4).
The official adjustment documentation – Maintenance Manual, Revision 4, January 1973 – stipulates that the ends of the lock pins, in the locked position, must protrude for
6.35 mm beyond the rear face of the flanges (fig 5).
In consequence, with this adjustment the lock tube in its locked position was 6.35 + 1.6 = 7.95 mm short of the correct locked position.
(2) Latches open
When the latches were open, the movement of the handle towards the closed position WR8 stopped when the lock pins came up against the front faces of the flanges.
Tests carried out on the same door, with varying adjustments of the extreme positions of the lock pins, showed that the force which has to be applied to the handle in order to force its closure depends on the extreme position (locked) to which the lock tube is adjusted.
When this adjustment is in accordance with the manufacture a requirement, ie when the ends of the lock pins protrude for 6.35 mm beyond the rear faces of the flanjges, it is physically impossible to force the handle even in the absence of the support plate for the vent door shaft (SB 52-3?).
On the other hand, when this distance of 6.35 mm is decreased, the force required fer forced closure also decreases. It becomes theoretically rdl when the end of the lock pin is in line with the front face of the flange.
During the tests carried out (with the lock tube adjustment 7.95 mm short of the correct position) the handle could therefore be closed (and the vent door apparently closed) with a force of 22 daN (about 50 1bs) (fig 7),
This closure was possible only because of deformation of the mechanism providing control transmission for the operation of the lock tube. The principal deformation affected the vent door shaft. The additional support plate specified by gR 52-37 (fig 6) was designed precisely to prevent 'such deformation.
It should be noted that the partial engagement of the lock pins as reproduced on the new door corresponds to the friction marks which they made on the edges of the es of the door of TC-JAV, which occurred only on the leading half of the edges (fig 8).
Conclusions:
The new door
Because of the defective adjustment of the extreme positions of the lock tube, the handle could be closed without excessive force, although the 3atches were not completely closed.
Defective closure could not be detected from the external appearance of the handle, vent
door and cargo door, unless a visual inspection was made through the view port provided
for that purpose.
Door of TC-JAV
The thickness of the striker shims made any correct adjustment of the lock pins impossible; any attempt to bring the ends of the lock pins to the correct distance of 6.35 mm beyond the rear face of the flanges inevitably led to damage to the lock limit warning switch.
The incorrect adjustment of this switch caused the flight deck warning light to go out when the door was still unlocked.
Because of the insufficient protrusion of the lock pins, the locking handle and vent door could be closed without excessive force, although the lock pins were stopped by the front face of the flanges (fig 7).
From the production and inspection documents received by the National Transportation Safety Board from Dougias, the aircraft manufacturer, it appears that the adjustments of the lock pins on fuselage Ho 29 (TC-JAV) gave a minimum pin protrusion of 0,25 inches (6.35 mm), account being taken of the accomplishment and verification of the work specified in EO ADA 7797 Change A.
These documents merely provide guarantees in accordance with prescribed forms, but the adjustments in question were also those shown in the Maintenance Manual (in particular
Revision 4, January 1973) and had to be verified or applied again by the operat.or when-ever any work was carried out on the door.
In brief, examination of the wreckage of the door of TC-JAV revealed defective adjustment of the lock limit warning switch. In addition, after the rods of a new door of the same definition had been adjusted to the dimensions measured on TC-JAV, it could be judged that the adjustment of the lock pins was likewise incorrect in the locked position.
The adjustment reconstructed in this way is consistent with that of the lock limit warning switch and also with the friction and other marks found an the lock pins and flanges. Finally, it provides an explanation of why the locking handle could be operated without excessive force although the latches were not fully engaged.
3.16.7 Research: accident on 12 June 1972 to DC-10-10, N 103AA near Windsor, (Ontario)
In the course of its work, the Commission of Inquiry studied the report of the National Transportation Safety Board, dated 28 February 1973, relating to the loss in flight of a similar aft cargo door on the left-hand side from an American Airlines DC-10-10.
Although the course of events and some of the causes are not exactly the same, nevertheless that accident presents points in common with the accident to TC-JAV:
The latches were not fully closed and the latch lock pins were not in place.
The flight deck warning light had gone out before effective locking had occurred.
The altitude reached by the American Airlines DC-10 was of the same order as that of TC-JAV when the door opened and the two bolts (connecting the fixed part of the latch actuator to the door structure) failed under the same conditions.
In the absence of pressure relief vents of adequate size between the passenger cabin and the aft cargo compartment, the sudden decompression in the cargo compartment caused damage to the cabin floor and its structure. This damage was less severe than in the case of TC-JAV in which the floor was more heavily loaded, but the functioning of the control cables was impaired in various ways, although it did not become completely impossible to control the aircraft.
In the conclusions of the NTSB report, it is stated that the probable cause of the accident
was the incorrect engagement of the latching mechanism and the design characteristics of
the system which permitted the door to be apparently dosed when the latches were not
fully engaged and the lock pins were not in place. Two recommendations had been issued
by the investigators:
modification to the locking system to make it physically impossible to position the external locking handle and vent door to their normal door-locked positions unless the lock pins are fully engaged;
the installation of pressure relief vents between the cabin and the aft cargo compartment to minimize the pressure loading on the cabin flooring in the event of sudden depressurization of the cargo compartment.
The first of these recommendations had given rise to the modifications specified in Alert Service Bulletin 52-35 and in Service Bulletins 52-27 and 52-37 (in the case of 52-37, only a start had been made with its application to TC-JAV).
Other modifications of the door closing system and methods of mitigating the effects of sudden depressurization of the aft cargo compartment were still under study at the time of the accident to TC-JAV.
Door position Analysis TC-JAV
6
Analysis
4.1 Analysis of the process of ejection of the aft cargo door on the left-hand side
The initiating factor in this accident was the opening and ejection of the aft cargo door
during flight.
Expert examination of the wreckage of the door, of which the closing system (latches, latch actuator and operating mechanism) was found in good condition, has revealed various deficiencies. The latter were such that the aircraft’s take-off was undertaken with the latches very near to their correct position when closed, but at the same time the links which control the latches had not achieved over-centre (fig 2) and as a natural consequence the lock pins could not have been engaged.
Under these conditions, the chain of operation between actuator and latches is not irreversible: any force exerted on the latches is re-transmitted to the actuator instead of being absorbed by the 4 stops provided for that purpose (fig 1).
The actuator withstood the compression force without displacement of its shaft, since it is irreversible. It therefore transmitted the force from the 4 latches to the two bolts (titanium D.25 inch in diameter) which attach its fixed part to the door structure.
The force on the latches is directly proportional to the difference between the pressure inside the fuselage and atmospheric pressure. The force is nil on take-off and increases progressively with altitude up to about 22,400 feet.
There is no way of knowing what measures were taken by the flight crew as regards to cabin pressurization. No malfunction had been reported and the flight level of 240 chosen for cruise and the fact that the aerodromes of departure and arrival had the same 'elevation give reason to assume that pressurization was under automatic control. In that case, at 12,000 feet the cabin altitude was close to sea level and the fuselage pressure differential must have been between 330 and 360 mb (4.7 and 5.2 psi). It should be noted that these are figures of the same magnitude as those estimated in connection with the previous accident at Windsor (Ontario).
The force transmitted to the actuator attachment bolts is the product of the force on the latches and the position of the lever arms of the system. (When the link arm pivots are at dead centre the force on the actuator bolts is zero; the force increases as the arms . move away from the dead centre position.)
The door therefore remained closed as long as the two bolts attaching the actuator to the door structure withstood the increasing pressurization force.
When the two bolts gave way, the latch opened and the door opened suddenly after breaking the top shaft of the door actuator.
As a result of the sudden stress on the fuselage combined with the dynamic pressure of the air, the door broke into severa3 pieces and became detached from the aircraft
For the configuration of the door of TC-JAV, the studies undertaken have shown that the incomplete closing of the latches resulted from incomplete extension of the actuator shaft.
The tests and research on the parts recovered from the wreckage failed to establish the process with certainty.
Either the control switch was maintained in an active position for too short a time (the modification contained in SB 52-44' had not yet been applied to T.C-JAV so that a visual light indicator showing that the shaft had reached the end of its travel was not available to the operator).
Or the extension of the actuator shaft stopped too soon because of:
the slip of its torque limiter;
the normal operation of the thermal protection trip device of the electric motor;
accidental cut-off of the electrical power supply.
Since the electric motor of the actuator was not found after the accident, it is impossible to establish which of the above reasons was the cause of the actuator’s malfunction.
Finally, it should be noted that the door had had to be closed by the manual drive tool on numerous earlies occasions, which would conf¿ the hypothesis of erratic functioning of the actuator.
4.2 Consequences of the ejection in flight of the aft cargo door on the left-hand side
The loss of the door caused an almost instantaneous drop in the pressurizetion, established in the cargo compartment beneath the passenger cabin floor.
The various pressure relief vents between the cargo compartment and the passenger cabin are not of a size to accommodate a discharge of air as large as that which passed through the door which had suddenly opened. As a result, there was an instantaneous excess pressure above the floor of the order of 36 KPa (about 3.6 tonnes/m2) ie the same order of magnitude as in the case of N 103 AA (cf paragraph 3.16.7).
In the case of TC-JAV, this excess pressure, added to the normal stresses on the floor, caused damage such that parts of passenger seats were ejected from the aircraft together with six passengers probably occupying two triple seat units in line with and above the cargo door. This damage was therefore clearly more substantial! than in the case of
N 103 AA in which the inifia1 floor loading was lighter.
Studies were undertaken in an atternpt to reconstruct the damage sustained by the controls, but the impairment of their functioning could not be established in precise detail. Nevertheless, because all the horizontal stabilizer and elevator control cables are routed beneath the floor of the DC-10 and because of the priority assigne4 in this aircraft to each of these mechanical controls, the state of airworthiness of TC-JAV after the loss of the cargo door and the disruption of the floor structure must have been such that the crew were left with no means of regaining sufficient control of the aircraft.
Analysis
4.1 Analysis of the process of ejection of the aft cargo door on the left-hand side
The initiating factor in this accident was the opening and ejection of the aft cargo door
during flight.
Expert examination of the wreckage of the door, of which the closing system (latches, latch actuator and operating mechanism) was found in good condition, has revealed various deficiencies. The latter were such that the aircraft’s take-off was undertaken with the latches very near to their correct position when closed, but at the same time the links which control the latches had not achieved over-centre (fig 2) and as a natural consequence the lock pins could not have been engaged.
Under these conditions, the chain of operation between actuator and latches is not irreversible: any force exerted on the latches is re-transmitted to the actuator instead of being absorbed by the 4 stops provided for that purpose (fig 1).
The actuator withstood the compression force without displacement of its shaft, since it is irreversible. It therefore transmitted the force from the 4 latches to the two bolts (titanium D.25 inch in diameter) which attach its fixed part to the door structure.
The force on the latches is directly proportional to the difference between the pressure inside the fuselage and atmospheric pressure. The force is nil on take-off and increases progressively with altitude up to about 22,400 feet.
There is no way of knowing what measures were taken by the flight crew as regards to cabin pressurization. No malfunction had been reported and the flight level of 240 chosen for cruise and the fact that the aerodromes of departure and arrival had the same 'elevation give reason to assume that pressurization was under automatic control. In that case, at 12,000 feet the cabin altitude was close to sea level and the fuselage pressure differential must have been between 330 and 360 mb (4.7 and 5.2 psi). It should be noted that these are figures of the same magnitude as those estimated in connection with the previous accident at Windsor (Ontario).
The force transmitted to the actuator attachment bolts is the product of the force on the latches and the position of the lever arms of the system. (When the link arm pivots are at dead centre the force on the actuator bolts is zero; the force increases as the arms . move away from the dead centre position.)
The door therefore remained closed as long as the two bolts attaching the actuator to the door structure withstood the increasing pressurization force.
When the two bolts gave way, the latch opened and the door opened suddenly after breaking the top shaft of the door actuator.
As a result of the sudden stress on the fuselage combined with the dynamic pressure of the air, the door broke into severa3 pieces and became detached from the aircraft
For the configuration of the door of TC-JAV, the studies undertaken have shown that the incomplete closing of the latches resulted from incomplete extension of the actuator shaft.
The tests and research on the parts recovered from the wreckage failed to establish the process with certainty.
Either the control switch was maintained in an active position for too short a time (the modification contained in SB 52-44' had not yet been applied to T.C-JAV so that a visual light indicator showing that the shaft had reached the end of its travel was not available to the operator).
Or the extension of the actuator shaft stopped too soon because of:
the slip of its torque limiter;
the normal operation of the thermal protection trip device of the electric motor;
accidental cut-off of the electrical power supply.
Since the electric motor of the actuator was not found after the accident, it is impossible to establish which of the above reasons was the cause of the actuator’s malfunction.
Finally, it should be noted that the door had had to be closed by the manual drive tool on numerous earlies occasions, which would conf¿ the hypothesis of erratic functioning of the actuator.
4.2 Consequences of the ejection in flight of the aft cargo door on the left-hand side
The loss of the door caused an almost instantaneous drop in the pressurizetion, established in the cargo compartment beneath the passenger cabin floor.
The various pressure relief vents between the cargo compartment and the passenger cabin are not of a size to accommodate a discharge of air as large as that which passed through the door which had suddenly opened. As a result, there was an instantaneous excess pressure above the floor of the order of 36 KPa (about 3.6 tonnes/m2) ie the same order of magnitude as in the case of N 103 AA (cf paragraph 3.16.7).
In the case of TC-JAV, this excess pressure, added to the normal stresses on the floor, caused damage such that parts of passenger seats were ejected from the aircraft together with six passengers probably occupying two triple seat units in line with and above the cargo door. This damage was therefore clearly more substantial! than in the case of
N 103 AA in which the inifia1 floor loading was lighter.
Studies were undertaken in an atternpt to reconstruct the damage sustained by the controls, but the impairment of their functioning could not be established in precise detail. Nevertheless, because all the horizontal stabilizer and elevator control cables are routed beneath the floor of the DC-10 and because of the priority assigne4 in this aircraft to each of these mechanical controls, the state of airworthiness of TC-JAV after the loss of the cargo door and the disruption of the floor structure must have been such that the crew were left with no means of regaining sufficient control of the aircraft.
Conclusions TC-JAV
7 Conclusions
Results of the Inquiry
The findings of the Inquiry are as follows:
The crew members held the certificate, licences and qualifications required for the performance of their duties in the type of aircraft and on the flight in question.
The aircraft was certificated, equipped and operated in accordance with national and international requirements; both on take-off and at the type of the accident, its load and centre of gravity position were within the appropriate limits.
Nevertheless, as regards the aft cargo door on the left-hand side:
A Service Bulletin 52-37, specifying the installation of a support plate designed to prevent forced closing of the 1ocking handle and the vent door in the case of incomplete engagement of the latching system, had not been applied to the air-craft before delivery and this oversight had not 5een detected at the time of delivery. It was found, however, that work on the application of this modification had begun on the lock tube where chamfering had been roughly carried out.
While the aircraft was in service, a modification (direct access to the drive mechanism) had been carried out in a way which did not comply with Service Bulletin S2-38.
The adjustments of the lock pins and the lock limit warning switch were incorrect.
The striker of the unIock limit switch had two shims of Douglas origin, surmounted by a shim with no reference and of a quality not to aeronautical standards.
During the aircraft’s stop at Orly, the aft cargo door on the left-hand side had been closed without any apparent abnormality, the locking handle had been pulled down and the vent door closed, although the 1ock pins were not engaged and no visual inspection had been made through the view port provided for the purpose of verifying that the lock pins were in place.
The take-off and climb progressed without incident until the aircraft reached approximately 12,000 feet at about 1140 hrs.
At that time, the aft cargo door on the left-hand side opened in flight and became detached from the aircraft structure.
The drop in pressure in the cargo compartment caused an immediate pressure differential which was sufficient to cause the disruption of the floor structure and the consequent ejection of six passengers, their cabin seats and various pieces of wreckage.
The deformation and disruption of the floor led to serious impairment of the controls af Ho 2 engine and of the flight controls of which,the cables run under this part of the aircraft structure and the damage was such that it was impossible for crew to regain control of the aircraft.
Because of the design of the mechanism as a whole the incomplete application of modification SB 52-37 (absence of support plate specified) and the adjustments found on measurement to"incorrect (lock pins and striker) it was possible for the door locking handle,to be pulled, down without the use of-any abnormal force and for the flight deck visual warning light to be switched off, when the latches were not fully engaged and the lock pins not in place. The tests and research have confirmed incomplete engagement of the cargo door latches and in correlation the non-engagement of the lock pins.
The Inquiry into an accident at Windsor (Ontario) on 12 lune 1972 had provided evidence of the grave risks entailed by sudden depressurization, of. the, cargo compartment: the inadequacy of the pressure relief vents had resulted in the disruption of the floor under which the flight control cables and, thereby causing the jamming or rupture of the cables.
5.2 Causes of the accident
The accident was the result of the ejection in flight of the aft cargo door on the left-hand side: the sudden depressurization which followed led to the disruption of the floor structure, causing six passengers and parts of the aircraft to be ejected, rendering No 2 engine inoperative and impairing the flight controls (tail surfaces) so that it was impossible for the crew to regain control of the aircraft.
The underlying factor in the sequence of events leading to the accident was the incorrect engagement of the door latching mechanism before take-off. The characteristics of the design of the mechanism made it possible for the vent door to be apparently closed and the cargo door apparently locked when in fact the latches were not fully closed and the lock pins were not in place.
It should be noted, however, that a view port was provided so that there could be a visual check of the engagement of the lock pins.
This defective closing of the door resulted from a combination of various factors:
incomplete application of Service Bulletin 52-37;
incorrect modifications and adjustments which led, in particular, to insufficient protrusion of the lock pins and to the switching off of the flight deck visual warning light before the door was locked; the circumstances of the closure of the door during the stop at Orly, and, in paiticular, the absence of any visual inspection, through the view port, ta verify that the lock pins were effecfively engaged, although at the time of the accident inspection was rendered difficult by the inadequate diameter of the view port
Finally, although there was apparent redundancy of the flight control systems, the fact that the pressure relief vent between the cargo compartment and the passenger cabin were inadequate and that all the flight control cables were routed 'beneath the floor placed the aircraft in grave danger in the case of any sudden depressurization causing substantial damage to that part of the structure.
All these risks had already become evident, nineteen months earlier, at the time of the Windsor accident, but no efficacious corrective action had followed.
...............................................................................................................
Department of Trade
ACCIDENTS investigation BRANCH
Turkish Airlines DC-10 TC-JAV Report on the accident in the Ermenonville Fozest, France on 3 March 1974
Results of the Inquiry
The findings of the Inquiry are as follows:
The crew members held the certificate, licences and qualifications required for the performance of their duties in the type of aircraft and on the flight in question.
The aircraft was certificated, equipped and operated in accordance with national and international requirements; both on take-off and at the type of the accident, its load and centre of gravity position were within the appropriate limits.
Nevertheless, as regards the aft cargo door on the left-hand side:
A Service Bulletin 52-37, specifying the installation of a support plate designed to prevent forced closing of the 1ocking handle and the vent door in the case of incomplete engagement of the latching system, had not been applied to the air-craft before delivery and this oversight had not 5een detected at the time of delivery. It was found, however, that work on the application of this modification had begun on the lock tube where chamfering had been roughly carried out.
While the aircraft was in service, a modification (direct access to the drive mechanism) had been carried out in a way which did not comply with Service Bulletin S2-38.
The adjustments of the lock pins and the lock limit warning switch were incorrect.
The striker of the unIock limit switch had two shims of Douglas origin, surmounted by a shim with no reference and of a quality not to aeronautical standards.
During the aircraft’s stop at Orly, the aft cargo door on the left-hand side had been closed without any apparent abnormality, the locking handle had been pulled down and the vent door closed, although the 1ock pins were not engaged and no visual inspection had been made through the view port provided for the purpose of verifying that the lock pins were in place.
The take-off and climb progressed without incident until the aircraft reached approximately 12,000 feet at about 1140 hrs.
At that time, the aft cargo door on the left-hand side opened in flight and became detached from the aircraft structure.
The drop in pressure in the cargo compartment caused an immediate pressure differential which was sufficient to cause the disruption of the floor structure and the consequent ejection of six passengers, their cabin seats and various pieces of wreckage.
The deformation and disruption of the floor led to serious impairment of the controls af Ho 2 engine and of the flight controls of which,the cables run under this part of the aircraft structure and the damage was such that it was impossible for crew to regain control of the aircraft.
Because of the design of the mechanism as a whole the incomplete application of modification SB 52-37 (absence of support plate specified) and the adjustments found on measurement to"incorrect (lock pins and striker) it was possible for the door locking handle,to be pulled, down without the use of-any abnormal force and for the flight deck visual warning light to be switched off, when the latches were not fully engaged and the lock pins not in place. The tests and research have confirmed incomplete engagement of the cargo door latches and in correlation the non-engagement of the lock pins.
The Inquiry into an accident at Windsor (Ontario) on 12 lune 1972 had provided evidence of the grave risks entailed by sudden depressurization, of. the, cargo compartment: the inadequacy of the pressure relief vents had resulted in the disruption of the floor under which the flight control cables and, thereby causing the jamming or rupture of the cables.
5.2 Causes of the accident
The accident was the result of the ejection in flight of the aft cargo door on the left-hand side: the sudden depressurization which followed led to the disruption of the floor structure, causing six passengers and parts of the aircraft to be ejected, rendering No 2 engine inoperative and impairing the flight controls (tail surfaces) so that it was impossible for the crew to regain control of the aircraft.
The underlying factor in the sequence of events leading to the accident was the incorrect engagement of the door latching mechanism before take-off. The characteristics of the design of the mechanism made it possible for the vent door to be apparently closed and the cargo door apparently locked when in fact the latches were not fully closed and the lock pins were not in place.
It should be noted, however, that a view port was provided so that there could be a visual check of the engagement of the lock pins.
This defective closing of the door resulted from a combination of various factors:
incomplete application of Service Bulletin 52-37;
incorrect modifications and adjustments which led, in particular, to insufficient protrusion of the lock pins and to the switching off of the flight deck visual warning light before the door was locked; the circumstances of the closure of the door during the stop at Orly, and, in paiticular, the absence of any visual inspection, through the view port, ta verify that the lock pins were effecfively engaged, although at the time of the accident inspection was rendered difficult by the inadequate diameter of the view port
Finally, although there was apparent redundancy of the flight control systems, the fact that the pressure relief vent between the cargo compartment and the passenger cabin were inadequate and that all the flight control cables were routed 'beneath the floor placed the aircraft in grave danger in the case of any sudden depressurization causing substantial damage to that part of the structure.
All these risks had already become evident, nineteen months earlier, at the time of the Windsor accident, but no efficacious corrective action had followed.
...............................................................................................................
Department of Trade
ACCIDENTS investigation BRANCH
Turkish Airlines DC-10 TC-JAV Report on the accident in the Ermenonville Fozest, France on 3 March 1974
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