Airline Uncovers No Problems in Tail Fin Inspections
American Airlines said Monday that it had finished inspecting the tail sections of its 34 Airbus A300 passenger jets and found no problems, though some engineers say the visual inspections ordered by the Federal Aviation Administration are not sufficient to detect internal cracks.
The National Transportation Safety Board is investigating why the tail fin of American Airlines Flight 587 to Santo Domingo, Dominican Republic, broke off just after the plane took off from John F. Kennedy International Airport in New York.
Two critical questions are whether the fin, which is made of a composite material that is lighter and stronger than metal, was already damaged in some way, or whether there is a design flaw that could affect more than 400 other A300 and A310 jets worldwide.
The fiery crash Nov. 12 killed all 260 aboard, as well as five people on the ground. NTSB investigators have said that this crash resembles nothing in their extensive files, because major structural components of aircraft are supposed to withstand even heavy stress.
Authorities have repeatedly said there is no evidence of terrorism or sabotage.
The composite material in the A300’s tail fin is made up of layers of carbon fibers embedded in a special resin. Material engineers say that the visual inspections may not detect cracks, which usually begin on the inside.
“This is a much more difficult inspection than it would seem,” said Ronald Bucinell, a professor of mechanical engineering at Union College in Schenectady, N.Y. “There are not a lot of visual indications that you can get.”
Several technologies, including ultrasound and thermal imaging, can be used to inspect the internal layers of composite structures. “It probably would be a good idea to do something more in depth,” Bucinell said.
American would not say whether the tail fin of the plane that crashed had been previously inspected using ultrasound.
The only other U.S. carriers using the A300 are FedEx and United Parcel Service, which have not finished inspecting their aircraft. Neither of these cargo airlines has reported finding any problems with the tail fins, also known as vertical stabilizers.
FAA spokesman Les Dorr said the agency had not ruled out more intensive inspections and would decide if any are warranted after getting the results of the checks.
American said special teams of mechanics, engineers, production supervisors and technical crew chiefs conducted its inspections, which the airline voluntarily initiated before the FAA order last Friday.
Aviation safety consultant Barry Schiff, a former Boeing 747 captain, said the evidence thus far points to a structural failure.
“Once that stabilizer began to fail, the pilots were in unknown territory,” Schiff said. “In effect, they were like test pilots flying something that wasn’t designed to fly that way. They had no way of knowing what to do.”
NTSB investigators are examining several factors that may have contributed to the crash, including the design and construction of the tail fin, the possibility that it may have been damaged on a previous flight or during maintenance, the role of another jet’s wake in precipitating the crash and the actions of Flight 587’s pilots.
