Did A Tire Failure Bring Down The Concorde? Were Years Of Warnings Disregarded?
Serviceability of its American-built tires questioned
Investigation into the crash of Air France Concorde has brought into question the serviceability of its American-built tires. Findings of a tire carcass on the runway lead investigators to question whether a tire explosion could have caused foreign object damage to both engines and punched holes in the wing fuel tank, causing the huge fire seen on amateur video.
Concorde tires are critical to the safe operation of the aircraft because they are inflated to 184 lbs. per square inch. A failure of a tire means an explosion with tire pieces flying in all directions, like pieces of shrapnel from a hand grenade. Exploding tires have brought down other aircraft. Both hydraulic lines and fuel tanks have been pierced in the past.
In 1995, for example, a taxiing Concorde suffered an exploded tire that penetrated the wing fuel tank, causing a massive fuel leak. An extensive investigation at the time was to consider wing fuel tank penetration from such a cause and to correct it. Parts of a metal water deflector designed to prevent water ingestion also disintegrated and compounded the problem. It was to be redesigned.
Other examples of tire explosions have plagued the Concorde, as well as other aircraft, resulting in near tragedies, as well as crashes resulting in deaths. Indeed the Concorde suffered tire explosions to such an extent that the NTSB recommended changes in procedures to avoid a disaster.
The Concorde tires are special as well. The French use U.S.-built Goodyear tires and the British use Dunlop. They are attached to magnesium wheels and are in turn equipped with sophisticated anti-skid and brake overheat warnings. In the past, tire explosion has been suspected to have been caused by malfunction of brake actuators, overpressure, overheating, and deterioration, to name a few.
A likely scenario of Air France Flight 4590 is a tire explosion on takeoff that shed debris into both left side engines and penetrated the fuel tank on the left side. The engines cannot accept this foreign object damage and, while the loss of thrust from one engine would not have resulted in a crash, the loss of two engines on one side made a crash at that point in the flight inevitable. The loss of fuel that was probably lit off by the engines was likely not the cause of the crash, but a symptom of the severity of the explosion that penetrated the fuel tank.
The French investigation must focus on why this tire exploded on this aircraft at this time. Was it due to unobserved excessive wear and tear? Was it due to overheated brakes on taxi that overheated the tire? Was it the failure to account for past lessons of tire explosion and failing to protect critical systems like fuel tanks from collateral damage? These questions are important, not only for this investigation, but also, hopefully, will result in standards applicable to all aircraft that will lessen the chance of catastrophic accident from something as benign as tire failure.
Current investigation focus is on a sixteen-inch piece of metal on the runway found after the crash, which is claimed to be not from the Concorde. It is viewed as the possible initiator of the tire explosion that brought down the plane. This finding, although important, must be weighed against the many Concorde tire failures where no piece of metal was the initiator, and the fact that a single tire failure by regulation and commonsense cannot be permitted to take down an airliner at a cost of one hundred and sixteen lives. There will never be a runway at a commercial airport entirely free of debris, so a small innocuous piece of metal cannot be permitted to cause such a tragedy.
There is no doubt that Concorde will fly again. If Concorde is grounded forever because of this accident, then every B-737, Airbus, and any other airplane that has crashed should also be collecting dust. Fortunately, because of the scrutiny paid to the tire problem, especially on this aircraft, means will be devised to minimize engine damage in the future, which hopefully will also make its way to other aircraft.
To this day, the Concorde is the crowning achievement in aviation. It flies faster and farther with greater payload than any other aircraft ever has. It is faster and flies higher than most new military aircraft do today or will in the near future. It can cruise supersonically longer than any military aircraft ever has, all on internal fuel, and it can deliver one hundred people safely and in comfort internationally and on time. It earns an operating profit and is maintainable in spite of its age in years. In short, if Concorde has suffered, it has been a victim of the politics of the seventies when innovation wasnít acceptable unless it was invented here. If the United States had not nearly bankrupted itself on the Vietnam War, it too would have had an SST and this Country and the rest of the world would have enjoyed transcontinental and intercontinental supersonic travel as only the U.S. can deliver it, in a big way. The U.S. supersonic transport design carried two hundred passengers and could fly at Concorde speeds over vastly longer routes, which would have made supersonic flight available to so many more.
What are the lessons of the crash of Concorde? They are not new, but are sadly refreshed.
First, aviation safety is no accident. It is the result of taking effective steps to prevent an incident from one day becoming an accident. The tire problems known for decades werenít solved in spite of near accidents, so now people are dead.
Second, no matter how great a pilot you are, or how well trained you are, if the airplane is broken, even the best pilot can become a victim. The flight deck crews of all Concordes are the best of the best, far above a pilot of average piloting skills to which all aircraft must be designed. When both of the port engines lost power at the critical juncture of takeoff, the airplane, its crew and passengers were doomed. These men fought valiantly to save their passengers, but were unable. They, too, were victims of the system that failed them.
Third, if timely steps are taken by regulatory authorities, further to their mandate of insuring safety of flight, aviation can be accident-free. The French DGAC and the CAA in Britain failed to adequately address years of tire failures and near accidents on Concorde. Had the steps now being taken been taken when the problem first arose, which undoubtedly was in flight test before it ever went into service; this accident would have been prevented. They didnít, and now there are deaths.
Concorde is who we are. It is one of the greatest examples of our desire to go further, faster, and higher than ever before. It is like all of us -- flawed. It can, like its creators, be fixed if the desire exists to make that sacrifice. We can all learn a lot from this tragedy and the years of glory that preceded it.
- Arthur Alan Wolk