FAA orders Boeing jet inspections

No serious incidents reported as a result of fuel pumps

WASHINGTON (CNN) -- The Federal Aviation Administration Friday issued an emergency order for airlines to inspect more than 1,400 Boeing aircraft for a potentially faulty fuel pump that could cause an explosion.

The FAA said no serious incidents have been reported as a result of the fuel pumps, but inspections have found chafed or misaligned wires in pumps that suddenly stopped working during flights. The damaged wires, in turn, can result in sparks, or arcing.

"Examination of failed pumps showed that arcing had occurred in the pump bearings both inside and outside of the explosion-proof cavity of the pump. Such arcing could result in an ignition source in the fuel tank," the directive says.

The FAA gave airlines four days to check their fleets and change their operating procedures so that fuel is kept in the center fuel tanks, until the problem can be further remedied.

The directive applies to more than 1,400 Boeing 737s, 747s and 757s. The FAA said the total amount of aircraft worldwide affected is about 3,300, and that it has notified civil aviation agencies around the world.

CNN NewsPass VIDEO CNN's Kathleen Koch reports that 1,400 Boeing jets are being inspected for defects in fuel pumps. (August 31) Play video

The FAA said the pumps are made by a Boeing supplier called Hydro-Aire, based in Burbank, California, and were installed in at least 116 jetliners during assembly, beginning in January of this year.

The FAA's "Emergency Airworthiness Directive" also requires U.S. airlines to check:

The FAA wants all the aircraft inspected because some of the potentially defective pumps may have been installed as replacement parts in older aircraft.

If the Hydro-Aire pump is found to be installed, airlines are being told to make certain they keep enough fuel in the center fuel tank to keep the pump submerged in fuel -- even when banking, climbing or experiencing turbulence.

Experts who studied the 1996 crash of TWA Flight 800 determined that empty fuel tanks containing fuel vapors are highly volatile. Tests done on full or nearly full fuel tanks did not demonstrate the same volatility.

The FAA became aware of the fuel pump problem recently, when in three instances pilots noticed a "low-fuel pressure" indication and the pumps stopped working.

When mechanics took the pumps apart, they discovered chaffed or misaligned wires.

The incidents involved an Easyjet 737 Next Generation with only 500 flight hours. Mechanics, according to an FAA official, said the wires in the fuel pump were worn down to the point of shorting.

In addition, a Northwest Airlines 747 was brought into maintenance because of a low-pressure indication, and evidence of chafed wires and arcing was found.

The third incident involved a China Southern Airlines Boeing jet, which had its pump removed for repair and sent to Hydro-Aire. X-ray inspection showed that wires had been pushed down in the cavity of the pump and were not aligned properly.

Ron Wojnar, the FAA's deputy director of aircraft certification services, said that during manufacturing of the Hydro-Aire pumps, "wiring that supplies power to the pump is misrouted in some of the 1,250 pumps to the extent it may be caught in the rotating part of the pump."

If that wiring becomes chafed and is exposed to fuel vapors, Wojnar said, sparking could occur that would ignite the tank.

The FAA said that in a few weeks it will come out with a more permanent fix -- likely ordering airlines to replace the suspect pump.

The FAA said at least one carrier, Continental Airlines, has already checked its aircraft and determined none are affected.