Boeing continues to assert full confidence in the design and airworthiness of the 787, notwithstanding U.S. aviation authorities’ move last Friday to launch “a comprehensive review” of all “critical” systems following reports of a string of incidents involving the Dreamliner, most notably Monday’s fire within the aft electronics bay of a Japan Airlines airplane parked at Boston Logan Airport. During a press conference held in Washington, D.C., Friday morning, FAA Administrator Michael Huerta said the review of the airplane’s design, manufacturing and assembly processes will validate the work conducted during the certification process. The FAA will place particular emphasis on the airplane’s electrical systems, including batteries and power distribution panels, he added. Plans call for the review to start in Seattle with the FAA’s Transport Directorate and possibly spread to other locations over the course of “several months.”
Only two days earlier Boeing called on chief 787 program manager Mike Sinnett to defend the airplane’s record. Speaking on a conference call last Wednesday from Everett, Washington, Sinnett said the airplane’s “high 90s” dispatch reliability rate virtually matched that of the 777 at the same point in its service history. He also tried to allay any concerns about the use of lithium-ion batteries in the Dreamliner, calling the decision to use the 32-volt units “not the only choice, but the right choice” to meet the power requirements of the so-called “more electric” airplane.
A preliminary report released last week by the U.S. National Transportation Safety Board identified “severe fire damage” to the APU battery in the JAL 787. The event prompted scrutiny from the media over Boeing’s use of the particular kind of battery–known to present a fire hazard in the event of an overcharge or what Sinnett called an over-discharge condition. In response, Sinnett issued a sober explanation of the dangers and the “redundancies” put in place by Boeing to protect against both conditions, as well as the spread of fire in the event of an explosion.
“In the case of this APU battery we have four separate layers of protection,” said Sinnett. “Really the only faults left that we’d be worried about are internal faults in the manufacture of the battery, of its individual cells…We have never seen that in these batteries.”
Sinnett also insisted that the string of power panel faults that led to the grounding of a pair of United Airlines 787s and a Qatar Airways Dreamliner in December do not relate to the 2010 flight-test fire in Laredo, Texas, that delayed the program by six months. That problem, identified as an electrical arc inside the power panel, has not resurfaced, said Sinnett.
“We’re working to understand [the cause of the December incidents],” said Sinnett. “It is fair to say that those issues affected one and only one channel of electrical power generation capability [out of six.] The loss of only one channel represents no safety issue whatsoever and, in fact, we’re allowed to dispatch the airplane with one of those channels inoperative.” Meanwhile, said Sinnett, although the company hasn’t identified the root cause, it has traced the source of the problem to a single lot of circuit boards delivered by one sub-tier supplier.