More-electric aircraft

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 1 April 2001



(2001), "More-electric aircraft", Aircraft Engineering and Aerospace Technology, Vol. 73 No. 2.



Emerald Group Publishing Limited

Copyright © 2001, MCB UP Limited

More-electric aircraft

More-electric aircraft

Keywords TRW Aeronautical Systems, Aircraft, Aero engines, Power, Electricity

TRW Aeronautical Systems (Lucas Aerospace) highlighted many of its leading-edge technologies at the recent Airshow China 2000.

Supporting the effort toward the more-electric aircraft, TRW Aeronautical Systems has developed a complete range of flight control power-by-wire alternatives from electrohydrostatic actuation (EHA), including its Integrated Actuation Package (IAP), to electromechanical actuation (EMA), with the aim of replacing the hydraulic power supply to primary and secondary flight controls with electric power. Conventional flight control actuation, known as fly-by-wire, is controlled electrically, but powered hydraulically. These systems rely on a complicated network of high-pressure hydraulic tubes running throughout the aircraft to supply the hydraulic pressure needed to move each control surface. The goal of power-by-wire is to significantly reduce or eliminate altogether the hydraulic connection, and its associated risks, by providing electrical power straight to the actuators. The benefits are enhanced survivability and aircraft maintainability and reduced weight and aircraft ground service time.

The move toward more-electric flight controls generates greater electrical power requirements. To provide this increased electrical power without offsetting the weight savings gained from more-electric flight controls, TRW is further developing its pioneering variable frequency generator, which generates higher power output without significantly increasing weight when replacing a conventional constant frequency system. Applying the experience gained from providing what it believes to be world's first variable frequency electrical system on a civil jet aircraft, Bombardier's Global Express business jet, the company is now focusing its efforts on developing a variable frequency system for large aircraft. The variable frequency generating solution removes system complexity by eliminating the hydro-mechanical constant speed drive required in conventional constant frequency systems. The result is thought to be increased reliability and reduced weight and cost. TRW Aeronautical Systems is currently involved in a number of demonstration programmes proving the viability of variable frequency systems for large aircraft applications and has more than two years of successful testing behind it. Airbus has base lined variable frequency generation also for application on its A3XX.

Another area of focus is TRW Aeronautical Systems' engine controls. The company displayed its new FADEC (Full Authority Digital Engine Control) 2001, which is designed to meet the cost targets and timescales of the business and regional jet markets and is expected to enter service in this year. Described as rugged and reliable, the low-cost FADEC controls engine fuel flow by interfacing with the fuel metering unit and controls engine variable geometry via actuators. This innovative system is also said to be capable of controlling other standard engine functions. The low-cost FADEC has full built-in test and maintenance software, and utilises both low-cost hardware and software, making it a viable option for business aircraft operators.

TRW Aeronautical Systems also displayed its next-generation cargo power drive unit (PDU). The new PDU, which drives aircraft cargo containers into position, features an anti-scrub sensor to decrease roller wear, as well as electronic temperature sensing and electronic switching, which eliminates mechanical thermostats, thus increasing reliability. The PDU also allows for roller replacement without PDU removal and incorporates an automatically resetable thermal protector.

Further details are available from TRW Aeronautical Systems. Tel: +44 (0)121 451 5975; (US) Tel: +1 703 648 0831; Web site: