The modern crew station of Army helicopters uses the helmet as an integral component of the aircraft control systems. What was once viewed as a simple device for crash protection now supports devices including night vision goggles, chemical mask, head-up displays, and weapon aiming systems. These devices combine to increase the biomechanical stress in the neck. This study investigated the effects of increasing helmet torque on the motion of the helmeted head under the conditions of long-duration wholebody vibration exposure.
Twelve U.S. Army volunteer aviators were exposed to four hours of wholebody vibration, similar to that found in a UH60 helicopter, while wearing four different helmets. Helmet torques, as calculated at the point where the head connects to the spine, ranged from a standard aviator helmet to a helmet with a chemical mask and a night vision goggle. Head motion was measured using a three dimensional active infrared marker system attached to a fixture held in the subjects teeth.
Results showed no significant differences (p& lt;0.05) in head pitch motion over time for helmets, but significant differences among helmet torques. These results support the existing recommended helmet design of limiting the added helmet torque to 90 Ncm for long-duration helicopter flights.