Sources: Swissair Jet Had Type Of Insulation Involved In Other Fires
The Washington Post
WASHINGTON - Investigators probing the wreckage of Swissair Flight 111 have found pieces of a type of thermal and sound insulation that has been implicated in the rapid spread of fires on at least four other jetliners, the airline said today.
FAA Administrator Jane Garvey, interviewed today on ABC's "Good Morning America," said investigators don't know whether the insulation played a role in the crash, "but I think it's fair to ask those questions."
The thermal insulation blankets, which look similar to home insulation, met all Federal Aviation Administration standards for fire retardance and were used in aircraft for many years. But a series of aircraft fires from 1993 to 1995 persuaded McDonnell Douglas, manufacturer of the Swissair MD-11, to recommend in 1997 that the blankets be replaced at "the earliest practical maintenance period" on at least 1,000 jets.
Canadian investigators are far from determining the cause of the Sept. 2 crash of the New York-Geneva flight off the Nova Scotia coast in which 229 died, and the role of the insulation blankets - if any - will not be determined for some time.
After the crash, Boeing, which merged with McDonnell Douglas last year, decided to bring together all carriers that use McDonnell jets at a meeting, beginning today, to consider speeding up implementation of previous manufacturer recommendations regarding fire and smoke. Sources said the blankets - made of a metalized Mylar - will be one of the major issues under discussion at the Long Beach, Calif., session.
The blankets insulate the aircraft from heat and noise. They are installed under the aircraft skin and in other areas where heat might be a problem, such as the electronics bay at the front of the aircraft.
They were placed on at least 1,000 McDonnell Douglas aircraft before their use was stopped. A spokesman for Boeing said the company does not know how many of those planes have been retrofitted with newer insulation. The insulation apparently was not used on original Boeing aircraft or Airbus aircraft.
Information developed so far in the Swissair investigation indicates that heat, and possibly flames, spread through portions of the cockpit and the forward portion of the plane. "Heat-distressed" wreckage from the cockpit has been found.
In Zurich, Swissair spokesman Erwin Schaerer confirmed today that metalized Mylar was used on the MD-11 that crashed.
Jim Harris, a spokesman for the Transportation Safety Board of Canada, confirmed that a small amount of both types of insulation had been found, none of which exhibits indications of burning. Large amounts of wreckage will likely be recovered next week when a major dredging operation begins, he said.
The insulation blankets are unrelated to the issue of wiring insulation, including Kapton insulation, which received much news attention after the crash. Sources close to the probe said there is no indication so far that Kapton was a factor in the crash.
The pilots reported smoke in the cockpit, and then for about 10 minutes made an orderly descent down to 10,000 feet to dump fuel. Although they had donned oxygen masks and prepared for an emergency landing, they did not display urgency about their situation until they declared an emergency and told controllers "we have to land immediate."
Within less than a minute, the aircraft's electronic systems apparently shut down. Little is known about the last six minutes before impact because the two on-board recorders and the plane's radar transponder had stopped.
Sources said the plane's cockpit voice recorder offers little help at the end of the recording in determining what the pilots saw that persuaded them to declare an emergency, but that it is clear the situation suddenly deteriorated in some way.
As part of the probe, investigators have learned of at least three aircraft fires from 1993 to 1995 in which electrical short circuits set fire to insulation blankets that became fuel for damaging fires - even though the blankets met FAA standards.
In none of those fires did the blankets initiate the fire. But the blankets allowed it to spread rapidly in the three incidents, which all happened on the ground, allowing passengers and crew to escape. In a fourth instance, maintenance crews started the fire when hot metal chips from an air drill ignited a blanket.
The first incident, on Nov. 24, 1993, involved a Danish twin-jet MD-87 at Copenhagen. According to the Aircraft Accident Investigation Board of Denmark, the plane was taxiing to the gate when smoke started to emerge from the service units at the rear of the passenger cabin. After passengers exited, the smoke intensified "drastically."
"A fierce fire then erupted and spread very quickly," said an FAA report based on the Danish investigation. "Investigators determined that the thermal acoustical insulation blankets acted as fuel sources which helped to spread the fire."
One of the fires involved an MD-11. On Sept. 6, 1994, the crew of a China Eastern MD-11 noticed smoke in the cockpit as pilots prepared to start their engines at Beijing. They found a fire spreading in the electronics bay beneath the cockpit. The Civil Aviation Administration of China, in a May 24, 1996, report, said molten metal from a short circuit dropped on insulation blankets, igniting them.
Copyright (c) 1998 Seattle Times Company, All Rights Reserved.