|The NTSB has found a new focus for its investigation into TWA Flight
There is no longer any doubt that the NTSB determination of probable
for TWA 800's explosion is going to be faulty wiring. Exacerbated
"galley fluids" and leaky toilets perhaps.
Two Reuters articles follow:
Focus of TWA 800 crash
on wiring - NTSB
WASHINGTON, Sept 14 (Reuters) - National Transportation Safety
investigators are focusing on possible sparking from aging wires
cause of the 1996 TWA Flight 800 crash off Long Island that killed
people on board.
James Hall, chairman of the NTSB, told NBC's Today Show that testing
wiring bundles in 25 different planes has focused U.S. aviation
attention on Boeing 747's electrical system as a possible cause
"We are now looking very closely at possible electrical discharges
have come off of some of that wiring that could have caused the
itself,'' Hall said.
NTSB investigators have long suspected that fumes in the plane's
tank were ignited by some sort of electrical fault.
Hall was speaking from Calverton, Long Island, where the reconstructed
wreckage of TWA 800 was being moved to a smaller hangar Tuesday.
On Monday, USA Today reported that the private laboratory hired
by the NTSB
to test Poly-X wiring -- the same type used in the destroyed
aircraft -- found that it sparked more than expected when bundles
of it were
Wet-testing simulates what might happen when cracked insulation
electrical wires is exposed to salt water or waste water from
galley or restrooms.
For his part, NTSB chairman Hall refused to confirm those results
NBC News interview, deferring any comment until the safety board's
report is released.
That report is expected early next year.
U.S. panel told all aircraft
wiring ages, cracks
By Tim Dobbyn
WASHINGTON, Sept 15 (Reuters) - All aircraft wiring ages, and
it is not
uncommon to find five to 10 insulation cracks per 1,000 feet
of wire in
active aircraft, a congressional subcommittee heard Wednesday.
Armin Bruning, an engineer who heads a company that has done testing
National Transportation Safety Board, said the plastics insulating
aged, leading to problems ranging from minor troubles with instruments
fires and sometimes deaths.
Wiring is becoming one of aviation's hottest safety topics, with
role in two high-profile crashes in the last four years. There
has also been
increased research into the problem.
A Federal Aviation Administration official told a hearing of the
Transportation subcommittee that the so-called aging aircraft
soon include heavily electronics-reliant aircraft of the 1980s
such as the
Boeing 757 and 767 and the Airbus A-300.
"The FAA and, indeed, the entire aviation industry are only now
have a greater appreciation and understanding about the need
nonstructural aspects of our aircraft,'' FAA Associate Administrator
Bruning, president of Lectromechanical Design Co., a Dulles, Virginia,
concern that has worked with the U.S. Navy, said humidity, high
and strain all contributed to wire aging.
Although not all insulation breaks lead to sparks or accidents,
it is best
to minimize the problem, he said.
TWA, SWISSAIR CRASHES
NTSB aviation safety director Bernard Loeb said the board's attention
been focused by two major crashes: the 1996 explosion of a TWA
jumbo jet off
Long Island, which killed all 230 people on board, and last year's
MD-11 crash off Canada's Nova Scotia coast, which killed the
229 people it
Safety investigators suspect that an electrical fault, possibly
in the fuel
measuring system, ignited fumes in the center fuel tank of TWA
In the Canadian crash, attention has focused on damaged wires
in the ceiling
of the cockpit.
Loeb said inspections of more than 25 other aircraft after TWA
wiring problems in all cases, ranging from lint and metal shavings
bundles to cracks in insulation.
The NTSB is following up with tests in which wire bundles contaminated
metal drill shavings are vibrated.
It was recently reported that another series of tests documenting
potential of TWA 800-type wire when contaminated with galley
lavatory waste showed surprisingly violent reactions.
Loeb said outside the hearing that the NTSB was also planning
to use an
operating Boeing 747 to check the effect of turning powerful
circuits on and off and the induction of strong currents into
Under one scenario, excessive electrical energy may have entered
fuel tank through the normally low-voltage fuel measuring system.
"The safety board is concerned that industry and regulatory efforts
been relatively ineffective in preventing the types of wiring
during the TWA Flight 800 investigation,'' Loeb testified.