One Engine Inoperative Cruise for Mission Performance Optimisation

Interest is growing in the use of one engine inoperative cruise to enhance the mission performance of multi-engined helicopters. This paper explores the concept by examining the use of twin engine cruise in the long range AgustaWestland AW101 triple engine helicopter. The paper presents the design features of the aircraft that support this capability, the clearances and limitations that have been flowed out to operators of the aircraft, analysis of the performance benefit arising from twin engine cruise, and examples of where the capability has been used to allow extreme range search and rescue missions to be achieved. The paper then presents considerations for the introduction of single engine cruise capability into twin engine helicopters.