ADVANCED FUEL CONTROL SYSTEM FOR TURBOSHAFT ENGINES

The introduction of FADEC based fuel control systems on helicopter turboshaft engines these last few years has considerably developed engine control functions. This has made the helicopter's preparation for flight easier and has reduced the pilot's workload, the engine and the power transmission system being automatically maintained within their limits. The helicopter manoeuvrability has been improved by the increased performances of the rotor speed governing functions. The ability to rigorously control the engine contingency ratings, which are significantly higher than the maximum continuous rating, has allowed to markedly improve twin-engine helicopter performance in OEI (One Engine Inoperative) conditions. Pilot aid functions to train to this engine failure configuration are incorporated into the FADEC. The application of the FADEC technology to small turboshafts is specific, the engine control equipment playing an important role in the weight and cost balance. In-progress and future research work aims at bringing the FADEC technology to widespread use on this type of engine, while improving failure tolerance and engine fuel control performances. The following topics are dealt with in this paper: engine control architecture optimization, measurement by means of optical sensors, fuzzy logic application, and use of an internal model.