part 7
Air Transat 961: Tail Damage Exceeded “Fail-Safe”
During the AA 587 crash investigation, after it was revealed, using ultrasound in 2002, that the aircraft from the 1997 incident in MIA (AA 903) had suffered a broken attachment lug for its vertical fin, Airbus made repeated statements regarding the “fail safe” certification requirement that one lug of the vertical fin could be completely broken and the aircraft was still “safe to fly.” These statements were alarming as Airbus seemed to completely ignore the limitation that the “fail safe” design only ensured a safe recovery after the damage to the single lug—not continued operation for nearly five years. At that time, the pilot group made the point several times that, if you do not use effective inspection methods to discover hidden damage within the composite, there would be no way of knowing if damage had occurred to one lug, or multiple lugs. The NTSB revealed in this latest announcement that Air Transat 961 suffered severe damage to two lugs. Whether the rudder broke off cleanly or caused “flutter” it is clear that Air Transat 961 demonstrated that even pieces of a rudder can cause sideloading significant enough to severely damage a vertical fin beyond even the “fail safe” margin.
Particularly in the above paragraph “b”. the NTSB has stated quite clearly that in this recent incident, Airbus has issued a directive that did not adequately address the concern about the delamination of composite material and the inspection methods to clear the aircraft for safe flight; it chided Airbus for inappropriately suggesting that certain aircraft be exempt from the inspections; and it was in open denial of the Airbus directive to continue flying even if some rudder surfaces had been exposed to hydraulic fluid as it shared the same concerns that the Airbus pilots expressed in 2002 about “baseline data has not been established to ensure the integrity of composite” in the situation that Airbus had attempted to apply. The patched middle attachment lug of AA 587’s vertical fin had no “baseline data” on which to continue under service after having 21 metal bolts drilled though the monolithic carbon-carbon fiber stand structure…nor did the aircraft from AA 903, which flew for five years with a cracked lug. The Chief Scientific and Technical Advisor in the area of Composites, Dr. Larry Ilcewicz, testified at the NTSB hearing in 2002 that:
“In the case of the accident in 1997, because we had an unknown load level that, as a conservative approximation, could have been within 1% of failure. The decision was made that we do not have a database where that tail had been loaded to within 1% of failure and then taken for a lifetime’s worth of load, and so the decision was made to remove it from service.”
New Data
The NTSB, in the March 24, 2006 Safety Recommendation, has released significant data that throws new light on some of the presumptions made in the AA 587 investigation concerning un-commanded rudder; the vulnerability of the vertical fin from damage due to “rudder flutter”; the susceptibility of rudder composite material to damage, weakening and delamination from contact and intrusion with hydraulic fluid; and the attempt by Airbus to implement wholly-inadequate—indeed, irresponsible and dangerous—timeframes for inspection of this extremely urgent safety issue where passenger and crew lives –if Air Transat 961 or AA 587 are any indication--could hang in the balance. This new information must be fully considered with a “fresh look” at the other factors identified in the investigation—such as the rudder pedal design of the A-300, or the rudder design itself—so that all connected factors might be discovered, assessed and the future of air travel benefit from the conclusions.
Pilots: Re-open AA 587 investigation
Given this new information, we call upon the NTSB to re-open the investigation of the crash of AA 587 immediately.
Captain Rxxxxx Txxxxxxxx
Captain Pxxx Cxxxxx
Captain Gxxxx Sxxxxxx
First Officer Txxx Wxxxxxx
First Officer Jxxxx Gxxxxxxx