Procedure, Detecting Noises With BORESCOPE
The borescope is used to check and search for other information about the noise source that still cannot be detected, and when it is in locations that cannot be seen with the bare eyes without needing to perform a large removal procedure. The borescope allows the various inner components to be seen.
Example:
It is possible to check the ventilation doors, fans or push rods on the bulkhead.
It is possible to check metal particles and their condition in the bearings.