Excerpt from the article

http://www.newsday.com/news/opinion/ny-opeva014836268aug01,0,4310360.story?coll=ny-viewpoints-headlines
10 years after Flight 800, just hot air

Two federal agencies disagree over need to eliminate vapors from all airliner fuel tanks; it may take a new tragedy to prove the necessity
BY DAVID EVANS
David Evans, who was editor of the newsletter Air Safety Week when the TWA 800 disaster occurred, is the editor of Aviation Maintenance magazine.

August 1, 2006

What has the FAA done to address those issues in the years since the Flight 800 tragedy?

There have been endless and earnest meetings, and various directives have been issued seeking to prevent ignition sources in fuel tanks. But the FAA has only issued a proposed requirement to prevent fuel-tank explosions through an "inerting" process that fills voids in the tanks with nitrogen-enriched air. It also has left airline manufacturers to their own devices by only proposing - not yet requiring - inspections of aircraft wiring.

On its new B787, Boeing is installing an inerting system for both the center section and the wing fuel tanks. European manufacturer Airbus has designed the A380 double-decker without a center wing tank and claims it has eliminated all potential sources of ignition from its wing tanks so the weight and complexity of an inerting system is not necessary.

Thus, we come to one of the problems the FAA has created for itself. The agency has suggested that inerting systems are needed only for center tanks with nearby heat sources (such as air-conditioning packs, which warmed the fuel vapors on TWA 800). But the NTSB has recommended that flammable vapors be eliminated from all tanks.

The May 4 explosion of a Transmile Airlines B727 at Bangalore, India, in which a wing tank exploded as the airplane was being repositioned for ground maintenance, seemed to bolster the NTSB position. In a July 20 letter to the FAA, the NTSB, which was supporting a probe by Indian aviation authorities, said investigation of the incident "revealed that the ignition occurred where [fuel] pump motor wires had melted though aluminum conduit, exposing the fuel vapors to potential ignition energy." Although the aircraft had been modified in accordance with an FAA directive to prevent the wiring problem, the design change was clearly ineffective. Inerting is necessary, the NTSB said.