ARMY AVIATION SYSTEMS TEST ACTIVITY EDWARDS AFB CA
Vibration and temperature measurement tests were conducted on a production UH-1H helicopter to define the vibration and temperature environment for instruments, avionics, pilot station, and other component parts during firing and nonfiring flight. Testing was performed by the United States Army Aviation Systems Test Activity, Edwards Air Force Base, California, between 24 March and 16 June 1972. The testing consisted of 19 flights totaling 20 productive testing hours. Vibration data were recorded from 49 accelerometer locations for 55 flight conditions, and narrow-band spectral analyses were performed on the vibration data. The results of the spectral analyses were summarized by use of statistical methods. The primary source of low-frequency vibrations was the main rotor. Gunfire-induced vibrations were less than main rotor-induced vibrations. The highest vibration levels were recorded at the 42- degree gearbox at gear mesh frequencies. There were three shortcomings amplification of main rotor-induced vibrations by avionics vibration isolation mounts, pilot station vibrations in excess of the military specification limits, and excessively high Wet Bulb Globe Temperature index at the pilot station under certain environmental conditions.