FLIGHT TESTING OF THE CHANDLER EVANS ADAPTIVE FUEL CONTROL ON THE S-76A HELICOPTER

A full authority digital electronic control (FADEC) incorporating unique state-of-the-art adaptive features was flight tested on the S-76A helicopter. This paper presents the advantages and disadvantages of an adaptive control to manage the twin engine response of a modern, lightweight, highly maneuverable aircraft. For comparative purposes, reference will be made to the production engine hydro-pneumatic fuel control, uniquely installed in tandem with the experimental adaptive control, whose characteristics represent the majority of engine management systems currently in use. Details to be presented will substantiate a 3:1 improvement in engine power turbine governing when operating in the adaptive control mode. Additional flight test information will also investigate the automatic engine surge protection feature (adpative control of the acceleration schedule) and automatic fuel consumption minimization by varying main rotor RPM. In conclusion, flight test substantiated recommendations will be presented that will detail the future usage and expected benefits on the performance and operational characteristics of advanced powerplants to be derived from adaptive control technology.