抄録
In-flight vibration measurements were conducted to evaluate whole body vibration of aircrews in
CH-47J LR helicopter which is long range version of twin-engined CH-47J. The vibrations were
monitored by a triaxial accelerometer fixed to the floor and the seat cushion surface at both positions
of the co-pilot and the loadmaster in 2 different payload sorties under controlled flight conditions.
The effects of the vibration were assessed in accordance with current international guidelines (ISO
2631-1:1997). The accelerations associated with the rotor blade passage frequencies, 3.75 Hz, 11.25
Hz, 22.5 Hz, measured on all recorded positions. The root-mean-square values (0.60 and 0.61 m/s2)
of the frequency-weighted acceleration for the co-pilot’s seat surface were in the health guidance
caution zone for 4 hours exposure in the level flight with the highest air speed (130 kt). The results
suggested potential health risks of longer duration or repeated flight operations.
