ELECTRONIC CONTROL FOR HELICOPTER ENGINES

This paper describes the development of a full authority electronic helicopter engine control. The design was based on the fact that the capability of electronics is increasing rapidly. Consequently the maximum use should be made of electronic computation with the mechanical functions minimized. In order to avoid the traditional requirement for precise fuel metering, the system uses a novel closed-loop acceleration mode. The system reduces pilot workload by providing isochronous rotor speed governing and torque management. Fail-safe design has been applied effectively to eliminate hazardous defect modes. Also, complete isolation is provided between the engines in multiple-engine systems such that no one control failure can affect both engines. The reliability of the system is enhanced by utilizing thick and thin film circuits that integrate many devices into a single sealed component. The system has undergone bench certification tests, has been fully engine tested on the Lycoming LTS 101 and will shortly be flight tested.