What follows was submitted by a Concorde Flight Engineer not long after the accident just after take off from Charle de Gaulle Airport on the 25th of July 2000. It is reproduced here for the convenience those who have yet to read Learning to Operate a Concorde. It reflects my personal view of events and those of many involved in Concorde operations.
They offered conclusions as if they were facts. It seems to me that much of the effort of the investigation was to avoid any liability falling on Air France.
Yes, the strip of metal caused the tyre to fail, but Concordes have experienced many tyre failures; so why was this different?
The spacer left out by Air France engineering allowed a bearing, between the leg and the bogie beam, to migrate. With all tyres inflated the gear would still run true. With one tyre deflated, the bogie beam would rotate out of a true forward/aft alignment by a minimum of 3.8 degrees. This is why the 22 degrees of rudder applied by the pilot, which was reduced to 16 degrees at about 180 Kt., showed no measurable effect on the aircraft heading. Why full rudder was not applied has not been addressed. With the aircraft heading towards the grass it is entirely understandable that the pilot would rotate early and slow to avoid ripping the gear off on the grass. But why when they got airborne so slow did they shut down number 2 engine some 20 Kt below the minimum safe speed to climb out on three engines? Why was manual contingency not selected? Are these Air France training problems?
I contend that it is not possible to cause enough deflection on the lower wing skin to push outwards such a large part of the structure with only the energy from the tyre mass travelling at that speed and hitting the wing either at a significant angle or at a speed lower than the debris release speed. Even at the full release speed, I contend there is not sufficient energy.
The only conclusion I can offer is that the skin was preloaded by the tank being pressurised by operating the fuel pre take off burn off in a non-standard way: using the inlet override selection to tanks 5 and 7 with tank 11 pumps on.
This was then not cancelled before the start of the take off. Circumstantial evidence of this is that the pre take off burn off was not complete when the captain asked the flight engineer how much fuel they had burned shortly before take off. The flight engineer may, therefore, have been “cheating” fuel forward.
BEA has assumed that the engineer saying “54%” was proof that the CG was in the correct place. I suggest it is far more likely that it was his report that the take off CG switch was being put to the 54% position. Tank 2 exploded very shortly after take off proved by the number 2 dry bay hatches that were found just past the end of the runway, the parts from the tail and the hydraulic shut-off cocks for green and yellow hydraulics that are mounted on the common wall between tank 2 and the number 2 dry bay. A full tank will not explode and tank 2 contents gauge was the only one, at the crash site, that was at or near zero.
A burn through is most unlikely as the fire, in fire terms, was very rich and therefore relatively cool. We all know that the bottom of an aluminium kettle will not melt when there is liquid in the kettle. Tank 2 was like the kettle if the fuel was in the tank. Something else must have made the hole in tank 2 to allow sufficient fuel out for there to an explosive vapour. BEA has offered no realistic explanation.
There is a chunk of runway concrete found near the tyre failure site. This has not been explained. What lifted it and propelled it to one side? History suggests that the most likely cause of this type of damage is a jacking pad being dropped on the runway. That would be a chunk of metal well able to make a serious hole in tank 2 and allow sufficient fuel to escape to rapidly empty the tank.
The very strong smell of fuel on the ground following the aircraft’s path was mentioned in the first report but seems to have been overlooked in later reports. Fuel could have left tank 2 so fast that it passed through the flame without igniting possibly causing the fuel spill that was responsible for the smell.
I could go on about errors in the BEA report, such as the reason for the gear not retracting and the cause of some master warnings. I have brought all of them to the attention of BEA but few have been answered or addressed.
I am lead to believe that the British Accident Investigators were unhappy with the report and even the French admitted that the legal restraints were the greatest cause of frustration for them.
I fear the report was a cover up; not a reasonably reached conclusion.
Ian V Kirby,
Concorde Flight Engineer, (Ret’d)