TOKYO, March 7 Japan's All Nippon Airways
had three instances of electric distribution panel
trouble in its Boeing 787 Dreamliner before it grounded
the aircraft in January and had to replace the panel twice, a
In the most serious case, which took place in April 2012,
ANA found burns in the protection circuit and the breaker of an
electric distribution panel during on-ground inspections after
pilots received a generator-related bug message, ANA spokesman
Etsuya Uchiyama said on Thursday.
The company believes a foreign material entered the panel
and caused the short circuit. The material is likely to have
scattered and damaged the breaker, and ANA replaced the damaged
panel, he said.
"We believe this is not serious. Fire damage in electric
distribution panels are also found in other types of aircraft,
and it has no impact on safe operation of aircraft," he said.
ANA, which is Japan's largest airline and the biggest
operator of 787s worldwide, reported the case to Japan's Civil
Aviation Bureau, Uchiyama said.
The airline also replaced an electric distribution panel in
June 2012 and exchanged parts in a panel in March 2012, he said.
These two cases were not reported to the Civil Aviation Bureau.
On Wednesday, the Japan Federation of Aviation Workers'
Unions said ANA experienced short circuits in its 787 electric
distribution panel at least five times between December 2011 and
October 2012, citing ANA mechanics.
Asked about the Federation's information, ANA's Uchiyama
said the panel problems occurred three times, not five.
The federation, which groups unions representing aviation
workers including mechanics, flight attendants and pilots, did
not mention Japan Airlines, the second-largest 787
JAL could not be reached immediately for comment.
Boeing did not immediately respond to a request for comment.
ANA operated 17 Dreamliners before the aircraft was grounded
in mid-January after lithium-ion batteries burned on two jets,
one in the United States and one in Japan.
The 787 uses a large electrical system with multiple
generators and power distribution panels to perform many
functions that on other jets are powered by compressed air from
the plane's engines.
In 2010, a power distribution panel caught fire during a 787
test flight. In December 2012, a United Airlines 787 made an
emergency landing due to electrical problems stemming from a
distribution panel. Boeing later said it traced that problem to
a faulty circuit board made in Mexico.