Aircraft-Electric-Accessory-Vibration Investigations

Flight and laboratory tests are in progress to determine changes in design of aircraft generators which will improve their resistance to vibration-fatigue failure. Vibrations near mountings of generator voltage regulators and reverse-current relays are being measured to provide data for design and testingof these accessories. The paper presents flight vibration data and discusses sources of vibration in aircraft, accessory-vibration characteristics, vibration test apparatus, and investigations of failures of generator mountings and flexible drive asemblies. On the basis of the flight and laboratory tests and other avilable information, recommendations are made for the design of generators which will give most satisfactory mechanical performance. The primary requirements of a generator from the standpoint of avoiding vibration failures are a stiff mounting flange and a flexible drive assembly having a satisfactory damping device.