Search

Triaxial vibration levels were recorded on the CH-47C and SH-3A helicopters at the pilot's seat, collective control stick, rudder pedal, instrument panel, and the pilot's head (Z-axis only). These recordings were made on two separate two-hour flights for both helicopters. The first flight was a continuous mission profile representative of the helicopters' primary mission. The second flight consisted of discrete maneuvers representative of a broad scope of mission profiles. The resulting vibration tapes were subjected to spectrum analysis and three peak frequencies found. These peaks were seen to be a function of the rotor head frequency and two harmonics of this frequency. Each of the three peak frequencies was shown to be critical in terms of human performance parameters.