Aircraft

A Japanese investigation, into a China Airlines (CAL) Boeing 737-800 that had a fuel tank fire last year, has said it is highly possible CAL maintenance personnel failed to attach a washer to the bolt on the right wing slat and that is why the bolt moved, puncturing the fuel tank.

Japan's Aircraft and Railway Accidents Investigation Commission made the remark in its preliminary report into the CAL 737-800, local registration B-18616, that caught fire on 20 August last year soon after landing at Naha airport on the southern Japanese island of Okinawa.

The commission disclosed last year that it had found a bolt on the 737-800's right wing slat that had pierced the fuel tank creating a 2-3cm hole.

The fuel leaking from the tank then ignited creating a fire that completely destroyed the aircraft and led the 165 people on board to disembark quickly to safety.

But until the release of the preliminary report, the reason for the bolt moving had always remained unexplained.

The Aircraft and Railway Accidents Investigation Commission says since the incident Boeing has changed the design of the bolt nut to make it larger.

CAL has responded to the preliminary report by issuing a statement saying it "reviewed its maintenance records and confirmed that it completed the required inspections in a timely manner on its 737-800 aircraft" and in accordance with "Boeing's service letters and service bulletins."

"The aircraft involved in the incident completed its inspection from 6-13 July 2007, prior to the event in Okinawa," it adds.