The U.S. FAA--nearly 12 years after the inflight breakup
of TWA Flight 800--has issued a final rulemaking aimed
at eliminating the risk of catastrophic fuel tank
explosions.
Airlines, already staunching the flow of red ink, now
face budgeting in the cost of retrofitting aircraft with
the systems in the next decade.
The rule, long-awaited by the National Transportation
Safety Board, is aimed at preventing another TWA Flight
800 accident. On July 17, 1996, Paris-bound Flight 800,
a Boeing 747-131, broke up in flight shortly after
departure from New York Kennedy (JFK) Airport, and all
230 people onboard were killed.
Investigators determined that the breakup was probably
caused by the explosion of flammable vapors in the
center wing fuel tank. The source of the ignition was
never determined, but investigators thought it likely
that wiring in the fuel quantity indication system
caused a short circuit.
Since that day, the reduction of fuel tank flammability
has been on the NTSB's Most Wanted List of safety
recommendations. The FAA issued 70 advisory circulars
and 100 airworthiness directives aimed at mitigating
risks, most of which aimed at reducing sources of
ignition.
In May 2001, the agency issued SFAR 88 (Special Federal
Aviation Regulation) aimed at preventing ignition
sources, but did not issue a proposed rule until
November 2005.
The July 16 final rule follows the proposed rule, with
some exceptions. It would require Boeing and Airbus
passenger aircraft with heated center wing tanks (HCWT)
and manufactured before 2009 to be retrofitted with a
flammability reduction means (FRM), such as a fuel tank
inerting system, or ignition mitigation means (IMM),
such as polyurethane foam. (A fuel tank inerting system
replaces oxygen in a fuel tank with an inert gas, such
as nitrogen, to reduce risk of flammability. For the
full 223-page rule, go to
http://federalregister.gov/OFRUpload/OFRData/2008-16084_PI.pdf
In addition, the rule requires that an FRM or IMM be
installed on passenger and cargo aircraft with HCWTS
manufactured in the 2009-2017 period. Boeing 717, 727
and certain 767 and 777 aircraft, as well as Airbus
A321, A330-200 and A380 aircraft, are excluded.
Cargo aircraft are excluded from the retrofit
requirement. However, If an FMM/IMM-equipped passenger
aircraft is converted to cargo aircraft, the cargo
operator would be required to keep the system
operational.
The FAA estimates total compliance cost of the rule at
$1 billion, $975 million for air carrier passenger
aircraft and $37 million for production cargo aircraft,
over a 35-year period.
The final rule indicates that 2,732 passenger aircraft
would require retrofit, with kit costs ranging from
$77,000 to $192,000, depending on aircraft type. Total
retrofit costs would run $110,000 to 250,000 per
aircraft, costs that, over time, would decline
$10,000-17,000, according to the FAA.
In addition, 2,290 production passenger aircraft and 88
production cargo aircraft manufactured in 2009-2017 will
be affected by the final rule.
Photo of Flight 800's reconstructed TWA 747: National
Transportation Safety Board, via Skybunny at Wikipedia
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