19-Oct-1998
JAMES T. McKENNA/WASHINGTON
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.
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