P100 power panel focus of 787 fire probe

Washington DC
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Two days after a 9 November fire forced the grounding of the 787 test fleet, a power control panel, responsible for distributing electrical power generated by the aircraft's left engine, is at the center of Boeing's investigation.

Program and supplier sources confirm the panel, known as P100, caught fire as ZA002 was passing through 305m (1000ft) during its final approach into Laredo, Texas on Tuesday.

Boeing disclosed Wednesday that a power control panel was being replaced, but declined to identify if P100 was the source of the fire.

The P100 panel sits on the left side of the aft electrical equipment (EE) bay, and is part of a highly-integrated electrical system that receives 235v ac power from the left engine's twin 250 kVA engine generators for distribution throughout the aircraft.

An identical P200 panel performs the same tasks for the right engine's generators.

The larger electric systems architecture of the 787 is driven by up to one megawatt of electricity from the two 250 kVA variable frequency starter generators (VFSG) on each of the 787's General Electric GEnx-1B or Rolls-Royce Trent 1000 engines. ZA002 is powered by Trent 1000 engines.

The P100 panel is home to seven main components supplied by Hamilton Sundstrand, including those that are responsible for commanding loads on and off to various systems depending on the need on board the aircraft, as well as components that replace thermal circuit breakers, which provide overload and fault protection.

Further complicating ZA002's return to testing is the damage sustained during the fire, which included dripping of molten metal onto the system wiring and internal fuselage structure, which program sources say is driving Boeing's inspection of the area surrounding the P100 panel to "determine if other repairs will be necessary."

Boeing is continuing to investigate the fire to determine any impact to "the overall program schedule" as it reviews data collected from the incident.

The airframer is currently slated to deliver the first production 787 to Japan's All Nippon Airways in the middle of the second quarter 2011.