EAST COWES, ENGLAND - Westland Aerospace Ltd.'s composite air-intake duct on the MD-11 tail-mounted engine replaces an aluminum model that is 20 percent heavier. Westland technicians in England stiffen large carbon epoxy panels with preformed foam ribs and fabricate the 12-foot-diameter duct assembly for the No. 2 engine of the McDonnell Douglas Corp. wide-body aircraft.
``Westland developed the innovative manufacturing technique specifically for the intake duct and is delivering an assembly each month to meet the MD-11 production schedule,'' said Martin Marshall, a manufacturing engineer for Westland Aerospace.
Lengths of Rohacell-brand polymethacrylimide foam-core material, from Rohm GmbH of Darmstadt, Germany, are cut from planks or sheet, heated to obtain the panels' curvature and laminated in place between plies of carbon fiber.
Each panel is bag-cured in an autoclave and assembled with other panels in a jig to form the inlet duct.
``This technique reduces the manufacturing cycle by minimizing the number of processes and parts involved,'' Marshall said. ``It also reduces the time installing the duct on the aircraft.''
When assembled, the duct is about 20 feet long. The installation wraps around beams that transmit engine thrust loads to the main fuselage.
McDonnell Douglas began using the new duct with the 128th MD-11, which was delivered to KLM Royal Dutch Airlines in November. All future MD-11s will have the Westland duct. MD-11s are assembled in Long Beach, Calif.
Westland Aerospace, a subsidiary of GKN plc's Westland Group, employs 1,400 and has facilities at East Cowes on England's Isle of Wight that produce turboprop engine nacelles, turbofan nacelle structures and flight control surfaces.