A dual-duplex electrohydraulic system for the fly-by-wire control of a helicopter main rotor

This paper presents a study relevant to a fly-bywire flight control system for the main rotor of a helicopter, aimed at ensuring the maximum level of system safety while keeping the wiring complexity as little as possible. The system is quadruplex lectrical, dual hydraulic, arranged as a dual-duplex configuration. The paper addresses all main issues relevant to the fly-bywire control: system architecture, performance, monitoring functions, failure behaviour, reliability. The merits of this system and its behaviour for a reference helicopter under normal and degraded onditions, as well as during the transients following a failure, its etection and the consequent reconfiguration of the system control are all addressed in the paper.