Boeing's "more-electric" power architecture for the 787 will face special conditions to achieve airworthiness certification by the US Federal Aviation Administration.
The extra certification requirements released by the FAA require Boeing to prove the 787 "is capable of recovering adequate primary electrical power generation for safe flight and landing" in the event of an in-flight power failure.
The 787 design omits the heavier pneumatic systems used on its predecessors to power hydraulics controlling flight-control systems and landing gear, in favour of electric power for the hydraulic actuators. The twinjet's engines drive four integrated drive generators producing 1.45MW of electricity, which provide the primary power source for the flight controls and gear.
The FAA recognises the 787's electric power as a potential safety concern that must be addressed by imposing special conditions beyond its normal airworthiness-proving requirements.
Boeing must show the 787 is capable of safe flight with the engine and APUs inoperative. Alternate sources of power may include the battery, ram air turbine or a permanent magnet generating system.
The manufacturer must also prove that the 787 has enough alternate sources of electrical power onboard to descend from the maximum operating altitude to the minimum altitude to attempt an engine and APU restart.
Source: FlightGlobal.com
