CTSB: Faulty Airbus Bond Caused Loss Of Rudder
Ever since the fatal crash of American Airlines Flight 587 into the streets of Belle Harbor on November 12, 2001, many locals and aviation experts have pointed to the laminate bond that holds the tail structure together as the culprit for the crash, even though the National Transportation Safety Board (NTSB) ruled that the first officer effectively pulled the tail from the Airbus A300-600 by overagressively using the rudder in a wake turbulence upset.
Now, however, the Canadian Transportation Safety Board (CTSB) has lent credence to the theory that the Airbus 300 series tails are flawed, by ruling that an Airbus A310, basically the same aircraft as the A300 that crashed in Belle Harbor, lost its rudder on a flight from Cuba to Canada because the laminate material in the tail section of the plane lost its bond.
On March 6, 2005, Air Transat Flight 961, an Airbus A310-308, took off from Cuba's Veradero Airport with nine crew and 262 passengers on board.
Ninety miles south of Miami, Florida, the flight crew heard a loud bang and felt some vibration in the plane. The aircraft entered a Dutch Roll, simultaneous oscillations and a sideslip, what pilots call "tail-wagging." Flight crew at the rear of the aircraft were thrown around, and some were injured. The crew took the plane up to a higher altitude and eventually brought it back to Cuba, where it was discovered that the rudder had fallen off over the ocean. However, the rest of the tail section remained attached to the plane, unlike the AA 587 crash, where the entire tail structure fell off the plane.
There are some similarities, however.
American Airlines Flight 587 departed from Kennedy Airport and turned over Jamaica Bay on its way to WAVEY, a waypoint about 35 miles southeast of the Rockaway peninsula.
About 66 seconds after liftoff, a loud noise was heard on the cockpit recorder. The plane began to oscillate. Witnesses on the ground reported to The Wave that the tail of the plane was moving back and forth. Pilots described that movement to The Wave at the time as a "Dutch Roll."
At 80 seconds out, the first officer, who was flying the departure of AA 587, called for full power. Loud popping sounds were heard on the cockpit recorder for a period of 11 seconds. The first officer, Sten Molin, reported that he was "losing control" of the plane.
At 103 seconds, its tail gone and its engines having dropped off, the plane crashed into the intersection of Newport Avenue and Beach 131 Street.
The NTSB report on Flight 587 found many of the same rudder movements that were experienced in the Air Transat incident. The NTSB blamed those rudder movements on the first officer's use of the rudder pedals.
The Canadian Board, with much of the same information, blamed the rudder movement on the fact that it had delaminated and was no longer aerodynamically correct.
Scott Jordan, an aviation expert from San Jose, California, has been following both the AA 587 and the Air Transat upsets.
"The bang, followed by the escalating yawing and rolling reads like a twin of the AA 587 events," he told The Wave. "The [CTSB] report suggests that the excessive rudder deflections were made by part of the rudder that was not aerodynamically effective. I wonder if a similar scenario might exonerate the pilots of AA 587."
The CTSB report said, "The aircraft took off from Varadero with a pre-existing disbond or an in-plane core fracture damage to the rudder, caused by either a discrete event, but not a blunt impact, or a weak bond at the Z-section of the left side panel. This damage deteriorated in flight, ultimately resulting in the loss of the rudder."
"The manufacturer's recommended inspection program for the aircraft was not adequate to detect all rudder defects," the report added. "The damage may have been present for many flights before the occurrence flight."
The CTSB report says that the most likely scenario for the failure was that the disbonding of the rudder material grew during the flight. Having reached critical size, the damage rapidly propagated, resulting in a loud and sudden explosion of the skin. The separation damaged the opposite panel and created a large sideways force on the tail section. About a second later, there was a large aft and downward force on the tail, causing the rudder to rip from the tail section at the upper hinge points.
Very similar damage was found on the tail section of AA 587, which was fished from Jamaica Bay by police launches.
The NTSB, however, continues to stick to the findings of its report, even in light of the Air Transat report.
"[The report] is nothing new," said Ted Lopatkiewicz, a spokesperson for the agency. "The failure in the Air Transat upset was very different from AA 587. The two have nothing to do with each other. In fact, if the rudder had come off AA 587, the tail might have remained on the aircraft and it might have been able to make it back to JFK safely."