The FAA on Wednesday is expected to adopt a new rule aimed at preventing fuel tank explosions on commercial jetliners. Officials say the new rules will require aircraft to be equipped with systems that use nitrogen to prevent sparks from igniting hot vapors inside the tanks. The Air Transport Associated noted that the industry has already addressed the problem by eliminating ignition sources and that the rule would cost carriers $1.2 billion over a decade. "Our foremost concern will be the absolute safety of air travelers," an ATA spokesman said. "We believe that eliminating the ignition sources accomplishes that."