FAA Orders New Safety Devices To Prevent Fuel-Tank
Explosions
The FAA announced
Tuesday that it will require airlines to install safety devices in
order to to prevent fuel-tank explosions. However, the cost of
these fuel tank flame reduction systems -- or inerting systems
as they are often called -- is not cheap. The devices, which flush
oxygen from the fuel tanks, will cost airlines millions of dollars
to install.
The FAA's move appears to meet one of the key
recommendations (Safety Recommendation A-96-174) that was
issued by the National Transportation Safety Board after the crash
in 1996 of TWA Flight 800, a Boeing 747 that exploded shortly after
takeoff from New York City. All 230 people aboard died.
In the last 14 years alone, 346 persons have lost their lives
due to explosions of flammable fuel/air mixtures in airliner fuel
tanks. Here is a short list of some of those tragic accidents:
March 3, 2001
A Thai Airways International Boeing 737 bursts into flames
on the ground in Bangkok. Investigators find no evidence of a bomb
and trace the explosion to the center fuel tank. No passengers are
aboard, but an airline employee is killed.
July 17, 1996
A TWA Boeing 747 explodes after leaving New York City, killing all
230 aboard. The explosion is traced to the center tank.
Investigators with the National Transportation Safety Board say
they suspect that a short circuit created a spark that triggered
the explosion.
May 11, 1990
A Philippine Air Lines 737 explodes on the ground in Manila. The
blast ruptures fuel tanks on the wings, and the jet bursts into
flames. Eight passengers are killed. Faulty wiring is
suspected.
Nov. 27, 1989
An Avianca Boeing 727 explodes on a flight from Bogota to Cali,
Colombia. Investigators say a bomb detonated in the cabin and
ignited the center fuel tank, which caused a larger explosion that
destroyed the jet. All 107 people aboard are killed.
The safety board
concluded that a measure such as injecting non-flammable nitrogen
gas into fuel tanks was needed to ensure the tanks could not
explode. Since that time, the FAA has followed several
recommendations regarding the prevention of sparks or electrical
arcing in or fuel tanks. However, the latest mandate is the first
to address the specific issue of flushing oxygen from the fuel
system.
The FAA plans to give airlines seven years to install the
devices on existing fleets and additionally plans to order changes
in the design of fuel tanks on new jets to further reduce the risk
of explosion. The new devices work by slowly pumping non-flammable
nitrogen gas into fuel tanks. The theory behind the device assumes
that if the nitrogen reduces the normal amount of oxygen in the air
by half, fuel won't burn and the tank can't explode.
Officials say much of the credit for the new requirement goes to
FAA scientist Ivor Thomas. Thomas, a Scottish immigrant, has spent
years studying fuel tanks with Boeing and more recently the
government. He oversaw research at the FAA's William J. Hughes
Technical Center near Atlantic City into devices that extract
nitrogen from the air and pump it into fuel tanks. The
non-flammable nitrogen pushes out the air through vents. The oxygen
in air is needed to cause an explosion.
In a key finding late in 2002, Thomas demonstrated that less
nitrogen was needed than previously thought to prevent an
explosion. The FAA tests showed that a fuel tank would not explode
if oxygen levels were at 12 percent. That small difference allowed
engineers to design much smaller nitrogen gas systems,
substantially lowering the cost and weight of the devices. Some
military jets already contain equipment that pumps nitrogen into
fuel tanks to reduce the oxygen level to 10 percent or less.
While new for the
civilian world, these devices are not uncommon in military
aircraft, which tend to operate in unforgiving environments.
Nevertheless, the struggling airline industry must now work with
this expensive remedy for safety's sake.
The proposed changes would affect some Boeing and Airbus jets in
which the center fuel tank is heated by adjacent equipment. That
condition exists about 35 percent of the time the aircraft is in
operation. The devices would be installed on about 3,500 jets owned
by domestic airlines. That would bring the costs to roughly $350
million. Spokesmen for Boeing and Airbus said they had not seen the
FAA's proposal and could not comment. Airbus has insisted that its
jets are not at risk for fuel-tank explosions. Boeing says it has
already designed a device to protect fuel tanks on its jets.