Panel says maintenance error caused 2007 plane explosion in Naha

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TOKYO, Aug. 28 Kyodo -
Japan's transport safety panel issued a safety recommendation to U.S. and
Taiwan aviation authorities Friday saying a maintenance error caused a Boeing
jet operated by China Airlines to catch fire and explode in 2007 in Okinawa
Prefecture, transport ministry officials said.
On Aug. 20, 2007, after arriving at Naha airport, the Boeing 737-800 burst into
flames and exploded moments after all 157 passengers and eight crew members
evacuated safely.
In a report released Friday, the Japan Transport Safety Board concluded that
the explosion was caused by a maintenance error that caused a bolt to fall off
the aircraft's main wing and pierce a fuel tank, causing fuel to gush through
the hole and catch fire.
Pointing the finger at the insufficient measures taken to prevent such an
occurrence by manufacturer Boeing Co. and by airline, which was responsible for
maintenance, the board asked the Federal Aviation Administration and Taiwan's
aviation authority to make sure the two firms take measures to prevent a
recurrence.
It also called for improving fire services at the local airport, saying
firefighters were late in arriving at the scene of the explosion.
No one died or was injured in the incident because the pilot acted quickly to
evacuate the aircraft after being advised by a ground mechanic of a problem,
and because ground staff properly guided passengers to safety, the report said,
adding that it took only three minutes and 27 seconds to evacuate all the
passengers after the fire broke out.
The bolt installed in a support pillar of a slat on the front edge of the
aircraft's right wing fell off due to vibration because it was fixed only by a
nut and not backed up by a washer, according to the report.
The bolt then pierced the fuel tank when the slat was tucked into the wing and
forced it into the tank with considerable force, it said.
The board believes China Airlines mechanics failed to attach a washer when they
replaced the nut on July 6, 2007, about six weeks before the accident, at the
instruction of Boeing.
The nut has to be replaced via a small hole inside the wing with a diameter of
only a few centimeters, and a mirror is necessary to perform a visual check.
However, neither Boeing nor China Airlines have described the difficulty
involved in their instructions and failed to prevent the accident, it said.
Boeing has since modified the design of the nut, enlarging it to make it more
effective in preventing the bolt from detaching.
==Kyodo