Vibration Characterization and Health Risk Assessment of the Vermont Army National Guard UH-72 Lakota and HH-60M MEDEVAC

This study characterized and assessed aircrew vibration during operation of the UH-72 Lakota and HH-60M Medevac located at the Vermont Army National Guard. The ISO 2631-1: 1997 was used as the guideline for the assessments. Triaxial accelerations were collected at the floor/seat base, seat pan, and seat back interfaces at the pilot, crew chief, and medic stations. Data records were collected by aircraft task and flight test conditions. All stations aboard the UH-72 showed a major spectral peak in all three directions between 24 and 25 Hz. All stations aboard the HH-60M showed a major peak in all three directions between 17-17.5 Hz. These peaks were associated with the blade passage frequency of the respective aircraft. Based on the overall vibration total value (ISO 2631-1), comfort reactions for the UH-72 primarily ranged from not uncomfortable to fairly uncomfortable. Comfort reactions for the HH-60M primarily ranged from a little uncomfortable to uncomfortable. Based on the seat pan point vibration total value (ISO 2631-1), the UH-72 pilot station showed some level flight exposures that would cross the lower boundary of the Health Guidance Caution Zones into the potential health risks zone between 5 and 8 hours. None of the UH-72 crew chief exposures crossed the lower boundary in less than 8 hours. The UH-72 medic station showed that all level flight exposures would enter the potential for health risks zone between about 3.5 and 8 Hz. The HH-60M pilot and crew chief stations showed a majority of level fight exposures that would enter the potential health risks zone between 5 and 8 hours, and between 2 and 8 hours, respectively. The HH-60M medic station showed that all level flight exposures would enter the potential health risks zone between 1 and 5 hours, with higher airspeed records crossing the upper boundary between 4 and 8 hours, entering the zone where health risks are likely. Prepared in collaboration with Army Institute of Public Health, Aberdeen Proving Ground, MD and Infoscitex Corporation, Dayton, OH.