System Suitability and Pilot Workload Assessments for Instrument Flight Certification of a New Utility Helicopter

This paper presents the instrument flight certification procedure for, and major flight test results of, a newly developed military helicopter. Instrument flight certification is achieved by combining the evaluation of aircraft system suitability, flight characteristics, and pilot workload assessments during flight tests. The suitability of the aircraft system is determined by whether or not the instruments and equipment required for instrument flight are mounted on the aircraft and if they are installed properly and protected. The performance of the equipment installed is verified through both ground and flight tests. In addition, it should be verified that the aircraft has sufficient static and dynamic stability with respect to longitudinal, lateral, and directional axes. The static stability is determined by the tendency to recover after disturbance. The dynamic stability is also evaluated. As another important study, a series of simulated IMC flight tests were conducted and the pilot workloads assessed using the Bedford rating scale. The pilot workloads are evaluated not only for normal aircraft flight conditions, but also for malfunction of the stability augmentation system or essential flight instruments. After completion of the simulated IMC flight tests, actual instrument flights were performed under real air traffic control.