Air travel safety

The engines of a China Airlines plane caught fire soon after landing at Naha Airport, Okinawa, Japan last Aug. 20, 2007. All of the 157 passengers and 8 crew members were able to slide down emergency chutes and escaped unharmed.

The right engine of the Boeing 737-800 burst into flames at approximately 10:35am while the plane was taxiing to the airport terminal gate. The fire spread to the left engine.

Investigators later determined that a bolt from a slat in the right wing had pierced the fuel tank, causing the fuel to leak out and pool on the ground, and then ignited in the heat. The hole created in the tank had a diameter of 0.8-1.2 inches.

Slats are panels that slide out of the front edge, while flaps slide out of the rear edge, of an aircraft’s wings. Their function is to stabilize the plane during takeoffs and landings.

Investigators believed a worker failed to re-install a washer on a bolt in the downstop assembly after a maintenance check a few months back. In the absence of the small washer, the bolt came loose apparently as the slats were being retracted soon after the landing. The engine that caught fire was last inspected on July 13 this year.

There have been similar cases previously reported to Boeing Co. of the bolt penetrating the fuel tank in 737-800s. The aircraft maker has previously instructed airlines to inspect their planes.

The Federal Aviation Administration ordered mandatory inspections on all Next-Generation 737s in all airlines in the U.S.  Boeing has sold 2,287 of the Next Generation 737s all over the world and 783 are in service in the US.  The inspections were ordered immediately after the China Airlines accident. In four cases, inspectors found bolts had been dislodged in the slat assembly.

Depending on the outcome of investigations and further studies, Boeing will evaluate whether it is necessary to redesign the bolt on the slat.

A former top investigator at the National Transportation Safety Board commented that the China Airlines accident underscored the observation common among investigators, that little parts that seem so innocuous at the time of design and construction of an aircraft can sometimes cause significant, even catastrophic, results.

China Airlines has been hounded by tragic accidents. In 1994, a crash on landing at Nagoya Airport killed 264 people. Two fatal accidents followed, killing 186 people. In a fourth accident in May 2002, a Boeing 747 on a flight from Taiwan to Hong Kong broke up in mid-air, killing 225 people.