FAA
tightens jet tank rules
Boeing, others may
have to redesign fuel units
Thursday, May 3,
2001
By JAMES
WALLACE
SEATTLE POST-INTELLIGENCER REPORTER
The Federal Aviation Administration is about to issue the
toughest rules ever for fuel tank safety, requiring The Boeing
Co. and other aircraft manufacturers to undertake a comprehensive
review of the design of fuel tanks.
The aim is to prevent the kind of fuel tank explosion that
destroyed TWA Flight 800 in July 1996.
In addition, the new rules, which would cover about 7,000
commercial planes with 30 or more seats, will require beefed-up
maintenance and inspection programs for aircraft fuel tanks.
"Manufacturers will have to identify and anticipate
any failures that could lead to an ignition source and make
changes either through maintenance procedures, operation or
design to prevent that ignition source," FAA spokeswoman
Alison Duquette said yesterday.
The long-awaited rules will be announced within a week, she
said.
They come just two months after a center fuel tank exploded
on a Thai Airways Boeing 737 on the ground at the Bangkok
airport. A flight attendant was killed.
When it first proposed the rules in 1999, the FAA said they
would likely cost airlines and manufacturers about $170 million
over 10 years.
Duquette said the actual amount will be slightly less than
that.
But such estimates don't include the cost of any new designs
that might come out of the review.
The design review is expected to take manufacturers more
than a year, she said, and they will have to meet tougher
fuel tank flammability standards than ever before.
Manufacturers include Boeing, Airbus and makers of smaller
regional jets such as Canada's Bombardier.
It's not clear what kinds of fuel tank safety improvements
could come as a result of the new FAA rules.
"We are looking at a lot of things," said Liz Verdier,
Boeing's safety spokeswoman.
"We are not waiting for the FAA. We started that design
review a long time ago."
Whatever comes from the review must be consistent throughout
the industry, she said.
"So what's good for one manufacturer will be good for
them all," she said.
But even with the new rules, the debate over fuel tank safety
is only likely to intensify.
The National Transportation Safety Board has said the best
way to prevent fuel tank explosions is not to hunt for and
eliminate new ignition sources but to pump inert gas such
as nitrogen into the fuel tanks.
That approach has been rejected by industry in the past as
being too costly and unnecessary.
The FAA, which would have to order the kind of system the
NTSB has suggested for it to become mandatory in the United
States, said last year that the cost of the changes could
be reduced to about $1.6 billion by using a ground-based inerting
system.
An FAA advisory group is studying the issue and is expected
to issue a report to the federal agency in July. People familiar
with the matter say the group may recommend against an inerting
system because the new rules from the FAA would make the risks
of a fuel tank explosion too low to justify the expense and
difficulty of developing a ground-based inerting system.
When an earlier FAA advisory group rejected the inerting
idea in 1998, its final report said that if the industry did
nothing else, flammable vapors in center wing tanks could
be expected to explode on average about once every 4 1/2 years.
The FAA believes its new rules could further reduce the odds
of a fuel tank explosion to about once every 15 years, according
to USA Today, which first reported yesterday that the agency
was finally ready to issue its new rules.
The explosion of the center fuel tank of the Thai Airways
jet came 56 months after the crash of TWA Flight 800 in 1996.
In 1990, the center fuel tank of a Philippine Airlines 737
exploded while the plane was at the Manila airport. Eight
people died.
As was the case with the Thai jet, it was a hot day, and
the air-conditioning packs on the Philippine Airlines jet
had been running for some time when the fuel tank blew up
as the plane was being pushed back from the gate.
Fuel vapors in the center tank of the TWA 747 also had been
heated by air conditioning units that had run for more than
two hours while the plane was on the ground.
The cause of the Philippine Airlines explosion was never
determined.
The investigation into the fatal explosion on the Thai jet
is just beginning.
The safety board was unable to identify the electrical spark
that it believes triggered the fuel tank explosion on TWA
Flight 800.
But in its final report on the crash that killed 230 people,
the safety board said the industry needs to rethink its philosophy
of fuel tank design, which until now has been to eliminate
all possible ignition sources in fuel tanks.
The safety board favors an inerting system that would prevent
fuel vapors from exploding even if there is a spark.
In a recent interview with Aviation Today, Bernard Loeb,
recently retired safety director for the NTSB, characterized
any renewed hunt for ignition sources as a "bankrupt
approach."
"If you don't know what did it, how do you engineer
it out," he was quoted as saying.
Boeing's Verdier said that is an issue that will be dealt
with in the months to come as part of the design review under
the new FAA rules.
"Which is truly better? That's the issue," she
said. "We are trying to do the right thing."
P-I reporter James Wallace can be reached at 206-448-8040
or jameswallace@seattle-pi.com
http://seattlep-i.nwsource.com/business/21358_faa03.shtml
Explosions
are rare, but the FAA estimates that on the average jet, fuel
tanks are flammable 35% of the time. That could be reduced
to 25% with mandatory use of alternative air-conditioning
sources. Most of that risk occurs on the ground or shortly
after takeoff. Cooler air at high altitudes cools fuel tanks.
