Air Compressor mounted on generator (aka APU)

[BoaterAl]

Just a little airplane reference there... I was told once there is no such thing as a generator on a airplane. True or false ?

While doing generator fluid checks I cycled old reliable on and off. To my surprise the air compressor mounted on the top of the generator jumped up and down as the generator shut down. Checking the mounting bolts (4) they were all turnable with my fingers.
With a rubber cushion block in-between mount tower and the generator base pretty much absorbs the vibration and noise when the air compressor cycles on and off.
The four nuts and bolts needed to be just tightened slightly to draw them a little tighter and cushioned on the pads as intended. Nuts are nylon self locking and are unlikely to come loose. It appeared the rubber pads had just over time decreased in thickness.
Just a couple of turns drawing up the bolts solved the excessive jumping around.

If you find this same situation don't over tighten as the cushion will be compressed and should be snug and just a half turn more.

[Jon Wehrenberg]

An APU or auxiliary power unit (a turbine powered generator) is very common on larger planes. The APU is used exactly like our generators and that is in lieu of "shore" power.

It is rarely found on smaller planes and those that need power when on the ground often get power when needed from a grund power unit.

I did not have an APU on my dinky little plane but I had a plug for connection to a ground power unit.

[Woody]

My KC 97 had a 20KW 3 cyl gas (115/145) APU, the only way we could get enough juice when no ground unit avail.