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Agency finds certification tests inadequate, sees no need
to mandate the replacement of material on most transports

Reviews provoked by Swissair Flight 111's crash have convinced FAA officials that materials certified for use as nonflammable airframe insulation in almost all large transports built in the last 35 years may in fact be highly flammable if exposed to high heat.

But the agency's top officials said that is no reason to order airlines to replace the suspect insulation yet.

The materials in question were used in nearly 12,000 civil transports built by Boeing, McDonnell Douglas, Fokker and Airbus Industrie as far back as the 1960s. FAA officials said the only airliner whose insulation appears to be nonflammable under most conditions is the Lockheed L-1011. The cost of replacing all that insulation easily could top $1 billion, industry officials said.

an faa study completed more than a year ago concluded that standard tests to prove the flame-retarding capability of insulation do not expose the materials to accurate or realistic aircraft fire conditions. The FAA test typically exposes a test material to a flame of a specific intensity and duration to verify its ability to resist combustion.

Tests done at the FAA's Technical Center using full-scale aircraft sections showed that most insulations certified by the standard tests and in use today would fuel a sustained fire when exposed to high heat conditions such as electrical wire arcing. Only two insulation types--glass fiber and Curlon--each wrapped in heat-resistant polyimide, appear to have adequate fire-retardant qualities, said FAA Administrator Jane F. Garvey.

Garvey said there is no reason to order swift replacement of insulating material, despite the demonstrated shortcomings of the certification standard and the fact that insulation has been implicated in at least four transport aircraft fires. Inflight fires of all types account for about 7% of airline accident deaths, according to FAA and industry data, but they are the fourth-leading cause of such deaths.

Garvey instead opted for "urging" operators of the affected aircraft to replace the insulation "at any reasonable maintenance opportunity," with the polyimide-wrapped insulation types. FAA officials said they also are developing a new certification test standard for insulation. Materials in use today will be tested against that standard once it is implemented, they said, and those that fail may be ordered to be replaced.

Developing the new standard alone will take at least six months, they said.

FAA officials said they also are reviewing service bulletins issued for the affected aircraft, and the adoption of those bulletins by operators to determine their effectiveness in reducing known fire threats near insulating blankets.

The agency's actions baffled aircraft operators and safety officials. "If the FAA had known about this for several years, why did they wait?" one senior industry official said. "The airlines are going to end up paying for someone's lack of interest or inept decision-making over there."

FAA officials focused on the potential fire threat of insulation in the wake of the Sept. 2 crash of the Swissair MD-11 off Nova Scotia, which killed all 229 persons on board. Flight 111's crew reported smoke in the cockpit prior to the crash.

Investigators scouring maintenance, manufacturing and FAA records for clues to the cause of that accident discovered that FAA officials were aware of questions about the flammability of insulation long before Flight 111's crash. The aviation agency and the aircraft maker knew of at least three incidents in which an aircraft electrical fire was fueled by fuselage insulation. One of those fires occurred on an MD-11.

On June 24, 1996, the director of the China Aircraft Airworthiness Dept. advised the FAA of a September 1995 fire in an MD-11 on the ground in China that involved the aircraft's insulation.

As the crew of that aircraft was preparing for engine start, according to FAA information, the pilots "noticed a significant amount of smoke" coming from the avionics, or electrical and electronics (E/E) bay below the cockpit. The pilots discovered sections of the bay were on fire. Investigators later found that molten metal from arcing wires in the bay had fallen on the blankets of insulation under the bay, igniting them.

"There was extensive flame propagation from the insulation blankets up to the E/E bay with widespread damage," the Chinese official, Wu Xiangru, wrote.

Tests by Chinese officials demonstrated that the insulation could be ignited if exposed to high heat, which prompted Wu to recommend that FAA officials review the adequacy of the material's certification testing. FAA officials at the time maintained their test procedures were adequate. They said the Chinese officials' tests used conditions more extreme than the U.S. requirements.

There were at least two incidents prior to the one in China in which arcing of electrical wires ignited insulation fires on other McDonnell Douglas aircraft types. In another incident, hot shavings from a mechanic's drill ignited an insulation blanket. All of the fires occurred on aircraft on the ground.

Those incidents prompted McDonnell Douglas one year ago to urge that operators replace the metallized Mylar insulation with another type on at least 1,000 aircraft as soon as their aircraft maintenance schedules permitted.

That notice, in the form of a service bulletin, was issued about a month after a heavy maintenance check was completed on the aircraft involved in the Flight 111 crash. Swissair did not schedule further maintenance to permit a wholesale replacement of the insulation after that because "it was a non-priority recommendation" from the manufacturer, an airline official said, and it was never mandated by the FAA.

Investigators for the Transportation Safety Board of Canada may soon be in a better position to judge whether insulation played any role in the smoke emergency that preceded Flight 111's crash. Last week, after a 12-day delay for equipment repositioning and foul weather, they took steps to speed up salvage of that aircraft's debris from roughly 200-ft.-deep Atlantic waters southwest of Halifax.

Salvagers positioned an oil-field support platform, the Sea Sorceress, over Flight 111's 230 X 100-ft. debris field. They said they expect that a 100-ton crane on the platform should permit most of the aircraft's 143 tons of wreckage to be raised by this week, weather and sea conditions permitting. Sea Sorceress' operations in the debris field are restricted to seas of about 7 ft. The start of its work last week was delayed by seas twice that level.

Of key interest for investigators is the recovery and examination of wreckage from the nose section, particularly the flight deck and avionics that hold most of the electrical and electronic equipment.

Investigators are assessing whether a failure in an electrical panel behind the pilots on the right side of the cockpit could have been responsible for the smoke and other problems that eventually led the flight crew to declare an emergency and request an immediate landing just before communications with the aircraft was lost. Flight 111 plunged into the Atlantic about six minutes later.

They also are weighing whether a failure in the panel over the pilots' heads could account for the problems.

In addition to raising the vital physical evidence from the nose that investigators say they need to isolate the source of the problems, the Sea Sorceress should bring up large amounts of insulation from around the cockpit. Investigators will want to examine that material for signs of fire damage. Separately, investigators for the U.S. National Transportation Safety Board last week reviewed the cockpit voice and flight data recorders from a Delta Air Lines MD-11 that made an emergency landing at Shannon Airport in Ireland on Oct. 8, after its crew detected a burning smell in the cockpit. Those investigators also interviewed the flight crew about the incident.


İOctober 19, 1998, The McGraw-Hill Companies Inc.


A Division Of The McGraw-Hill Companies

İMarch 31, 2003 The McGraw-Hill Companies Inc.

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