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Module 13. Aircraft aerodynamics, structures and systems

Medium vibration of 4 to 6 times per revolution is experienced on a helicopter. The primary control method is

  • inspect main rotor head and main drive shaft
  • design of engine and gearbox supports
  • inspect loose fixtures and fittings

Explanation

A medium-frequency vibration of about 4 to 6 times per main-rotor revolution points to the main rotor head and main drive-shaft area rather than the rotor blades themselves. The primary control method is therefore to inspect the main rotor head and drive shaft, since blade-related faults produce one-per-rev (low-frequency) vibration.

sam1969 asking:

I selected
-Design of engine and gearbox supports
Medium and High frequency Vibrations – Depending on the helicopter the source may be engine and transmission cooling fan and accessories such as air conditioner compressors, or driveline components.
Any ideas?

Community Comments (1)

J
Jordi Posts: 198 28.11.2022 / 18:28
it is design and geabox supports indeed because Engine and gearbox rotate faster than the rotor.

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