THE US Federal Aviation Administration (FAA) has proposed to fine Boeing $13,6m - its second-largest penalty to date - for delays in telling airlines how to prevent fuel-tank explosions on 383 aircraft.

Boeing was given a December 27 2010 deadline to submit instructions on how to add explosion-prevention devices in its US-registered 747 jumbo jets and 757 single-aisle aircraft, according to a statement at the weekend by the FAA.

The Chicago-based company missed the deadline for 747s by 301 days, and was 406 days late for 757s, according to the FAA.

"We are committed to ensuring the safety of the flying public," US Transportation Secretary Ray LaHood said.

"Manufacturers must provide the necessary instructions so that the airlines can comply with this important safety regulation."

The fine is the largest proposed by the FAA since it sought $24,2m from AMR's American Airlines in 2010 for maintenance lapses that grounded its fleet of Boeing MD-80s in 2008.

Firms typically negotiate lower payments with the FAA.

The agency's action stems from a regulation that requires airlines to install devices that blanket centre fuel tanks with nonflammable nitrogen gas.

The rule resulted from the explosion in a Trans World Airlines 747 off New York on July 17 1996, that killed all 230 aboard.

The US National Transportation Safety Board ruled that a spark triggered an explosion in the tank, tearing the jetliner apart. Boeing officials just received word of the FAA's proposed penalty and were reviewing it, Miles Kotay, a company spokesman, said. Airbus SAS, Boeing's main competitor for civilian aircraft, met the deadline, according to the statement. The fuel-tank rule requires that airlines install the devices on half their fleets by 2014 and complete the effort by 2017.

"The FAA expects that most, if not all, operators will meet both the 2014 and 2017 deadlines, even if they received service instructions later than anticipated," the agency said.

Airlines sought a delay in installing the devices in a March 28 letter sent by the Washington-based trade group Airlines for America. The group represents large carriers such as Southwest Airlines and Delta Air Lines.