The FAA is hoping to propose a rule this fall that would require airlines to install equipment to lessen the chance of in-flight fuel-tank explosions. FAA Administrator Marion Blakey announced the initiative Tuesday, saying the rule is being considered because new technology, largely developed by the agency itself, is now available to displace some of the oxygen within fuel tanks with inert nitrogen. "We're taking this step because we have found a practical solution," she told a news conference. The new, roughly $220,000-per-plane rule would be phased in over seven years starting in 2006, 10 years after the NTSB determined the belly tank of a TWA Boeing 747 (Flight 800) exploded off Long Island, killing 230 people. It was not the first or the last event of its kind. In March 2001, a Thai Airways 737-400 exploded while sitting on a hot ramp at Bangkok's domestic airport. The NTSB released information that the recorded sound of the explosion was found similar to that of a Philippine Airlines 737-300 that suffered a center-wing fuel-tank explosion in May 1990. In November 2002 Emergency Airworthiness Directives were issued for Boeing 737 models. The system takes compressed air from the engines and passes it through a membrane that separates oxygen and nitrogen. The FAA's system dumps oxygen into the atmosphere and pumps nitrogen into the fuel tanks. The extra nitrogen cuts oxygen content by almost half, making combustion of fuel vapors virtually impossible. The systems cost $140,000 to $220,000 per plane and need about $14,000 worth of maintenance every year. They weigh less than 200 pounds. The NTSB, which has been pushing for some sort of action on fuel-tank explosion hazards, applauded the FAA proposal.