A new dimension may have been added to the 10-year effort to prevent fuel tanks from exploding in airliners. The right wing fuel tank on a Transmile Airlines Boeing 727-200 apparently blew up while the plane was on the ground at Bangalore, India, last week. There were no injuries or damage to anything else but it brought into sharp focus the NTSB's 10-year battle to prevent fuel-tank explosions after the NTSB determined a belly tank blew on a TWA Boeing 747 in 1996 off Long Island, killing everyone aboard. (Though more people were killed, that incident was not the first of its kind.) The FAA is now preparing a final rule (from this NPRM) that may require systems to prevent fuel-tank explosions to be retrofitted on all airliners. But the rule applies only to center tanks and not wing tanks like the one that cooked off last week. The proposed rule is being opposed by the Air Transport Association. The ATA says cash-strapped airlines can't afford the retrofits. Rather than trying to eliminate sources of ignition, the proposed rule sets flammability standards for the vacant space in fuel tanks known as the ullage. The most likely way of meeting those standards is to pump inert gas into that space to displace the oxygen. Boeing's working on just such a system and hopes to have it certified this year. There have been 18 documented fuel-tank explosions in airliners and the FAA predicts at least nine more over the next 50 years if something isn't done.