WASHINGTON — The nation's top aviation safety investigator said federal regulators should adopt a rule that would force airlines to modify their fuel tanks to prevent explosions similar to the one that downed a Trans World Airline jet 10 years ago, killing all 230 people on board.

Mark Rosenker, the acting chairman of the National Transportation Safety Board, said yesterday that modifications should be made not only to the center tank — which exploded in the TWA 747 shortly after takeoff from New York on July 17, 1996 — but also to the wing tanks, where a similar explosion occurred on a jet in India last month.

Investigators believe that a spark in the center fuel tank of the TWA jet caused vapors to ignite and explode. Since the crash, the aviation industry has focused on eliminating sparks in fuel tanks. But NTSB officials believe that pumping nitrogen into fuel tanks — a process known as "inerting" — would be more effective.

Nitrogen, an inert gas, would replace oxygen in the fuel tank, making it nearly impossible for sparks to occur.

"We have to eliminate the flammability potential, the potential for the explosions, and then we won't be talking about this issue anymore," said Rosenker, who was flanked by his top safety officials during a news conference at the board's headquarters.

But the airlines and some manufacturers are resisting calls to install nitrogen systems, arguing that the changes — at a cost of $500,000 per plane — would be expensive and that they have already found a way to eliminate much of the risk.

"There are two ways to eliminate fuel tank explosions: inert the tank or eliminate the ignition sources," said Basil Barimo, vice president of operations and safety for the Air Transport Association, a trade group that represents major U.S. airlines.

"Ten years ago, after TWA 800, we took the ignition prevention path ... We have done that, and we think we are there today."

Barimo estimated it would cost $1.3 billion to retrofit U.S. planes with inerting systems.

In November, the Federal Aviation Administration proposed a rule that would require airliners and manufactures to reduce the flammability of center fuel tanks in about 3,200 planes.

FAA spokeswoman Alison Duquette said officials are still reviewing comments from safety and industry groups and did not have a deadline for the rule to go into effect.

The FAA has issued more than 100 directives to airlines to fix fuel tanks problems since the TWA crash. The agency also developed one of the first reliable nitrogen systems for commercial aircraft, Duquette said.

She said the proposed rule focuses on center fuel tanks because the risk of an explosion is greater than in wing tanks.

Airbus, a major aircraft manufacturer, has urged the FAA to reject the proposed rule, arguing that modern fuel tanks have been designed to eliminate the potential for such explosions.

Boeing plans to install inerting devices on its planes in 2007, pending the results of tests, a company spokeswoman said.