Oh dear here we go again, so let me state that I have got no new information as to what caused the sad Concorde crash, but I might be able to help as to what happened in the past.
1] BA in the early years of operation did have a number of tyre problems with Concorde, but these were caused by FOD mainly on the departure stands.Concorde had very hard and high pressure tyres and so any FOD which was run over during push back or taxi usually penetrated the tyre and caused a deflation [slow or otherwise] of that tyre, but it now caused the other tyre on that axle to be overloaded, which usually caused it to shed its tread during the take off run. This detached tread usually damage the hydraulic pipes on the landing gear, sometimes damaged the wing, but nearly always was accompaanied by high vibration, surging engines [Usually both on that side]as the two engines ate the remains of the tyre. The vibration could be so bad that it was difficult to see the engine instruements. Once the tyre debrie had passed through the engine the vibration would stop and the engines operated normally, the only give away that they had run down was the yaw of the aircraft. Damage to the wing was normally done by the fibre glass/ metal water deflector in front of the tyres being ripped off [by the departing tread] and hitting the wing.
To over come this certain mods were introduced
1] Flat tyre detection system was introduced
2] Protection guards positioned over exposed hydraulic pipes on the the
landing gear
3] Stronger tyres and hubs were introduced
4] Metal reinforcing wires were fitted into the water deflector to prevent it
from detaching itself and so hitting the wing
All BA Concordes had all these Mods incorporated
Also BA introduced a vigorous inspection of the push back area prior to departure
If my memory serves me correctly by the 1990s only one company made the tyres for Concorde, which only used NEW tyres and not remoulds or retreads.
IIRC that company was Kleber
One thing about Concorde was that it had 3 hydraulic systems two normal and one emergency backup. These system were kept rigidly apart except at the flying controls power control jacks. Now Concorde had no mechanical back up to it's flying controls and so if all hyds was lost then there would be no way of controlling the aircraft, which as it was a delta wing would then pitch very nose up and possibly turn over.
If you look at the picture of the aircraft taking off you can see that the flames are playing over the port inner elevon PFCU and I suggest would not take long to melt the hydraulic pipes of all three system so causing a complete hyd loss and so complete loss of control of the aircraft
If my theory is correct the result might have been the same no matter what the crew did or how many engines were running.
Just to finish up with the missing spacer apparently was missing for the previous 3 round trips of Paris to New York and those crews did not mention having any problems with the aircraft.
Anyway a sad accident, as they all are.
Brit312