Japan sheds new light on 787 fault
Power-panel faults, while unrelated to the battery problems that have grounded the 787 since January, are another nagging issue with the plane's innovative electrical system.
On flights in March, April and June of last year, faults in power-panel circuit boards on Dreamliners operated by Japanese carrier All Nippon Airways resulted in error messages in the cockpit, said airline spokeswoman Nao Gunji. Each time, the panels were inspected after landing.
In the case of the fault on an April 7 flight, a circuit board was found to have shorted, causing "slight discolouration" from burning, Ms Gunji said.
ANA replaced all three circuit boards, she said.
The Japan Federation of Aviation Workers' Unions, which represents ANA pilots, on Wednesday highlighted the incidents at a news conference in Tokyo.
Shozo Tsue, the federation's secretary-general, said the April 7 incident "was serious and caused damage to the surrounding area".
Ms Gunji said the purpose of the news conference was to ask the government "to ensure the safety of the aircraft" and take the time to find out what happened.
The union's account reveals the April 7 incident as one of the four instances of power-panel short circuits cited in January by Boeing vice-president Mike Sinnett in an interview with The Seattle Times.
Mr Sinnett, the 787's chief project engineer, said in each of the power-panel incidents electrical arcing inside a circuit board - "a low-energy arc that lasted milliseconds, very small" - had damaged the board and shut down some of the plane's electrical power.
He said the small spark inside the circuit boards produced no safety hazard, only a loss of function that was handled by the plane's multiple, redundant power systems.
In January, Boeing had not yet found the root cause but, Mr Sinnett said, the problems had been traced to a batch of faulty circuit boards inside the power-distribution panels, which are located, like the batteries, inside an electronics bay.
Boeing said the investigation of the power-panel incidents was still ongoing.
Following the ANA power-panel faults, on December 4, another power-panel short circuit occurred on a United flight out of Houston, Texas, forcing the pilot to divert to New Orleans.
A few days later, a similar fault occurred on the delivery flight of a Qatar Airways 787 from Washington state to Doha.
And later in December, a second United jet was grounded after another power-panel malfunction.
Kazuo Harigai, assistant secretary of the union , said "there have been lots of problems with the [787] electrical system".
Boeing said that because the 787 had more electrical systems than other aeroplanes, "it stands to reason" that component malfunctions encountered in service had been "mostly electrical in nature". Tests may begin
The US Federal Aviation Administration is close to approving tests of Boeing's approach to fixing the batteries on its 787 jets - and the tests could begin next week. The FAA could still demand changes to Boeing's proposed battery design if problems develop in the laboratory and flight tests, which will take several weeks. But the decision to start the tests will be a big step in Boeing's efforts to get the innovative jets, which have been grounded since mid-January, back in the air.
Frequently Asked Questions about this Article…
Japanese airline All Nippon Airways reported faults in power-panel circuit boards on 787s during flights in March, April and June of last year. On April 7 a circuit board shorted and showed "slight discolouration" from burning; ANA inspected the panels after landing and replaced three circuit boards. Similar power-panel short circuits were later reported on United and Qatar Airways 787s in December.
No. The article says the power-panel faults are unrelated to the battery problems that have grounded the 787s since mid-January. They are a separate set of electrical issues tied to the plane's power-distribution panels and circuit boards.
Yes. A United flight out of Houston on December 4 was forced to divert to New Orleans after a power-panel short circuit. A second United 787 was grounded later in December. ANA inspected and replaced circuit boards on affected aircraft after landing.
Boeing's 787 chief project engineer, Mike Sinnett, said the incidents involved a low-energy electrical arc inside a circuit board that lasted milliseconds and damaged the board. He said the small spark produced no safety hazard and resulted only in a loss of function that the aircraft's multiple redundant power systems handled. Boeing has traced the problems to a batch of faulty circuit boards in the power-distribution panels, and the investigation is ongoing.
ANA inspected affected panels and replaced circuit boards after the incidents. The Japan Federation of Aviation Workers' Unions publicly highlighted the incidents and called on the government to ensure aircraft safety and thoroughly investigate what happened.
The U.S. Federal Aviation Administration is close to approving tests of Boeing's proposed battery fix for the 787. The article says those laboratory and flight tests could begin soon, could take several weeks, and the FAA could still demand changes if problems emerge during testing.
Boeing noted the 787 has more electrical systems than many other aeroplanes, so it "stands to reason" that component malfunctions encountered in service have been mostly electrical in nature. This higher electrical complexity has been linked to the types of faults reported.
Investors should monitor updates from Boeing and regulators about the ongoing investigation into faulty circuit boards, results of the FAA-approved battery tests, any new incident reports from airlines (like ANA, United or Qatar Airways), and official regulatory decisions. Those developments will clarify timing for returning grounded 787s to service and any further corrective actions.
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