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11th Jan 2002, 15:44
Just spent a fascinating evening at the local flying club listening to a presentation given by a member of the BA team involved in the modifications to Concorde. It was interesting for a number of reasons, but particularly as it put a number of items into perspective, and shed light on media initiated nonsense.

I thought others might be interested, so the following is the jist of what has been done to the aircraft. Although since this is from memory, I hope I’ve got most of the facts, and do the story some justice. The majority of this is from a BA perspective, but as most people will know, Air France staff were also involved in analysis and modifications.


Reasons for disaster:

- tyre exploding, as happened some years before in Washington, ruptured the port wing fuel tanks situated around the wheel wells. The impact of the tyre carcass caused a massive shockwave within the wing (and fuel tank) causing a large section of the underside of the wing to become ruptured.
- However, the rupture also caused wiring to become exposed and this initially caused the ignition of fuel. The quantity of fuel dumped by the aircraft was enormous. Some 35 tons was lost from the aircraft in four seconds. At this time, the aircraft was some way before V1. It is unknown why tyre deflation indicators did not initiate a RTO by the crew.
- The result of the FOD (from a tyre carcass, and port wing) but especially the massive fuel loss, resulted in engine surge, and resulting shut down by the crew. The continuing fuel loss caused further surging in the remaining port engine denying the aircraft the speed it required. Essentially, power was obtained only from 2.5 of the four possible engines.
- Severe damage had occurred to the flying surfaces of the port wing and hydraulic systems of the aircraft. This eventually led to loss of control of the aircraft, and ultimately her flipping over and crashing.

Was a missing wheel spacer a factor in the disaster?

- it is not considered that this was the main cause. Of interest is that the aircraft gradually drifted to the left on the take-off run, but it is considered the missing spacer did not contribute to this drift. However, it is not clear why the skipper did not apply a more significant opposing control movement to counter the drift (after analysis of the control movement in relation to the drift).

Objective of Modifications to the aircraft

- the main objectives for the modification of the aircraft were to prevent huge fuel loss in the event of a tyre blow-out, which, firstly caused the engines to surge, secondly was ignited. It was agreed through simulation tests with Rolls-Royce, that the engines could cope with a small drip, but in the case of Paris, the massive quantity dropped by the aircraft was the primary reason for ignition, and engine surge.
- Reduce the severity of a tyre blow-out. (Due to the high speeds of Concorde, tyre blowouts do occur, and the aircraft can land quite safely on 7 tyres).

Modifications to the aircraft

- the main modifications have been made with the Kevlar lining in the fuel tanks in both wings. Not all fuel tanks have Kevlar lining, just those considered to be in the danger area from an exploding tyre. Kevlar is used within most military jets. It is bullet-proof.
- The Kevlar does not prevent any fuel escaping from a ruptured tank. This is due to a number of reasons, but particularly in the cooling requirements of the wing as a result of the liquid in fuel tanks. If armour plating, or Kevlar lining, was applied directly to the airframe (so no fuel would touch the airframe) then the wing would overheat. As a result, the Kevlar actually sits slightly off the airframe, and small holes in the Kevlar allow fuel to sit between the lining and the airframe. Therefore an acceptable drip rate (to prevent engine surge) would ocurr in the case of tank-rupture, but this not lead to catastrophe.
- Kevlar lining has to be individually made for each aircraft, as Concorde was hand-made, each one is slightly different.
- Emergency procedures were put in place in the event of an engineer having breathing problems while in the fuel tanks fitting the Kevlar, or in case of a heart attack. This resulted in a procedure being on hand for ripping open the wing to extricate the stranded engineer. This would have most likely resulted in the aircraft being written off. Since some of the fuel tanks were so small, advertisements for those of a diminutive stature were placed around BA engineering (although they probably didn’t use those words!) to get into the hard-to-reach places.
- New radial tyres applied to the aircraft, and alterations to the disk-brake temperature requirements.
- Wiring looms in and around the danger areas where replaced with steel coated looms to prevent any possible ignition source.
- A new interior was fitted out to the aircraft. Originally, this was going to happen as part of a new look to the aircraft. The business case was founded on a simple principle: the interior was much lighter than the old one, therefore it would pay for itself (over a period of time) due to the fuel cost savings. After the modifications, and the new interior fitted, the weight of the aircraft is about the same as before.

Testing of Aircraft

- a number of taxi checks were undertaken with the aircraft (Alpha Foxtrot was used).
- Initial flight checks, consisted of testing aircraft in the air for an amount of time equivalent to a trans-Atlantic crossing.
- Final check resulted in a complete flight to NY city and back.

Aircraft in service

- three BA aircraft are currently in service, having been fitted out with the new interior. A fourth is being currently fitted out (AD). A decision will be made on AC in the next few weeks, and decisions will be made in the coming months on AA and AB. The modifications are timetabled at about 45 days, with subsequent flight checks.
- One flight per-day is currently flown. It is anticipated a twice-daily service will return in September (the normal time of year when the summer schedule is increased to two flights). A Saturday service is flown to Barbados.
- Current loads are pretty good, with JFK flights have around 70 seats full, Barbados about 85. (Concorde needs about 50 seats full to break even). On initial flights, tickets were discounted, but on one occasion all discounted tickets (2K a pop) were taken in three minutes.

Flight crews and Cabin Staff

- Most of the flight crews have remained with the fleet. A few number of captains holding 744 ratings went back to that fleet, however the majority have remained. Since everyone had lost their currency on the aircraft, the first number of flights were taken by the chief pilot and the fleet training captain, before others were then checked-out. In the intervening period, crews were kept current on the sim.
- The cabin-staff were mostly re-assigned temporarily to serve in the first-class cabins of the 744 fleet.

Other useful titbits

- rotation speed in BA Concorde is 205kts.
- the aircraft currently flies with 96 pax which is a result of a damp aircraft. As the aircraft has been on the ground for an extended period, the normal result of Mach 2 flight, which is burning off any moisture accumulated on the ground, has not taken place. 98 pax will soon be the limit, with 100 (the full compliment) within a couple of months.
- reported in the press a few weeks ago was more media nonsense. The recent episode of “Concorde returning to T4 for a technical modification” was actually the captain taxiing the aircraft around the airfield to burn-off ramp fuel, since they had somehow managed to get cleared to the threshold much quicker than normal, as a result they where slightly too heavy.


I hope this is interesting for everyone. I personally find it a hugely fascinating aircraft, and when I used to live in Berkshire, I would always look out for Concorde in the morning at around 10.30, and on her return after 17.00. If I ever saw her depart from 09R, she was the only aircraft where people would stop on the perimeter road, watching in awe.

As if hewn from the most precious metals, comforted and carved in the hands of God, a machine never had more of a soul or exuded so much beauty.

Regards.

Kalium Chloride
11th Jan 2002, 15:50
Much appreciated and interesting, but just a thought:

Quote:

Although since this is from memory, I hope I’ve got most of the facts, and do the story some justice.

...er, I think you'll find this is exactly the kind of thinking that leads to...

Quote:

media initiated nonsense


Judge not lest you be judged.

stagger
11th Jan 2002, 16:36
Just a quick question...

There has been a lot of discussion on PPRuNe in the past about whether or not the Air France Concorde was above the MTOW for the conditions and whether this might have contributed to the outcome.

But if it really did lose 35 tons of fuel in a very short space of time how can this be relevant?

sickBocks
11th Jan 2002, 22:28
Good documentary about this on Discovery Wings entitled 'Concorde - The Comeback'. From both FD and Eng point of view.

hobie
12th Jan 2002, 04:47
to "no sponsor" ....... thanks for your posting ...... alpha fox came out to us for a number of training sessions last summer and I thought you might like to see the photo in the web add'y below ......

<a href="http://www.geocities.com/hobie_1_1999/hobiesphotossix.html?1010792493080" target="_blank">http://www.geocities.com/hobie_1_1999/hobiesphotossix.html?1010792493080</a>

everyone including the local retriever turned up to see her ...... wish the concorde fleet all the best for the future

BEagle
12th Jan 2002, 15:51
Indeed, the very best of luck to BA and their continued operation of the magnificent Concorde.

Specualtion regarding the ATOW, RTOW and whether the AF accident aircraft was over both MTOW and RTOW has not been to suggest that this was a primary cause of the accident - although the effect on tyre safety margins of operating above MTOW might be of note. However, if by virtue of the aeroplane being on the ground and hitting the FOD beyond the point at which it would have become airborne had it not, as has been suggested, been grossly over RTOW then the MTOW/RTOW/ATOW debate would be significant.

What is of great concern to many is the 'culture' which may exist in a company whose aircrew either failed to check the effect on their aircraft performance resulting from a significant wind velocity change, or who failed to act correctly when they did know that they were both over MTOW and certainly RTOW. As is a culture which apparently accepts uncommanded engine shut downs.