Boeing Finds Significant Damage To 787 Electric Panel

Fri, 11/12/2010 - 4:37am
SEATTLE (AP) -- An electrical fire that forced an emergency landing of a Boeing 787 test plane caused "significant" damage to a power panel and spread to a nearby insulation blanket, Boeing Co. said Thursday.

The Seattle Times, meanwhile, reported that Boeing engineering photos it obtained show heavy damage, including places where the panel's metal had melted.

The newspaper said a document accompanying the photos says the panel received "extensive smoke, fire and structural damage," and that before the plane can fly again, mechanics must thoroughly search for additional damage, including any to the plane's carbon fiber fuselage.

The 787 made an emergency landing Tuesday in Laredo, Texas, after the crew reported smoke in the plane and the fire briefly cut the plane's power. After landing, the 42 crew members and technicians on board evacuated down emergency chutes, with one person suffering minor injuries.

Boeing has grounded its 787 test fleet while it investigates the problem.

It's another setback for a plane already about three years behind schedule. Boeing had hoped to deliver the first of the new passenger jets to Japan's All Nippon Airways in the first quarter of next year.

Boeing has not said how the incident might affect deliveries or how long its investigation might last, but 787 program director Scott Fancher told The Times his team will take as long as it needs "to do it right."

Boeing said in a news release that a failure in the "P100" panel, in an electronics bay below the cabin floor and just to the rear of the wing, led to a fire in the nearby insulation, but the insulation self-extinguished once the fault in the panel cleared.

The P100 panel, a collection of electronic components, circuit breakers and switching gear, receives power from the left engine on the two-engine jetliner and distributes it to the plane's extensive electrical systems. Boeing said if it fails, backup systems, including power from the right engine distributed through the P200 panel, an auxiliary power unit, batteries and the ram air turbine -- essentially a wind-powered generator -- automatically come on line.

"The backup systems engaged during the incident and the crew retained positive control of the airplane at all times and had the information it needed to perform a safe landing," Boeing said.

The Times said senior Boeing executives told the newspaper the engineering photos reveal design details that could benefit competitors. At their request, The Times said, it decided not to publish the photos, but only describe them.

The photos show extensive scorching and a hole about 12 to 15 inches long centered at two boxes called contactors low on the panel, the newspaper said. The contactors open or close circuits as power needs of the plane change.

One contactor "caught fire and melted," The Times quoted the engineering document as saying. The other had "extensive fire and smoke damage to backside."

In addition, "The rear panel has melted," the document says. "The molten aluminum has dripped down causing potential damage to wire bundles, fuselage and stringers."

It says that before the plane can fly, mechanics must disassemble the P100 panel to determine the damage and check the plane's composite fuselage "where there were contacts with molten aluminum, burn marks and potential heat damage."

Boeing's news release said: "Molten metal has been observed near the P100 panel, which is not unexpected in the presence of high heat. The presence of this material does not reveal anything meaningful to the investigation."

Although thorough inspections are not complete, damage to the P100 panel "is significant," the statement said. "Initial inspections, however, do not show extensive damage to the surrounding structure or other systems."

Boeing said the burned panel and insulation have been removed for detailed examinations and replacements shipped to Laredo. It said it is studying data, creating a repair plan and determining what needs to be done to resume the flight test program.



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