The genius of the constant-speed prop is that it does exactly what its name implies: turns at a constant rpm set by the pilot, who really is adjusting the propeller governor
. The typical prop governor is a bolt-on device used to increase the engine oil's pressure and meter its flow into the propeller hub to hydraulically rotate the blades and change their angle of attack.
The diagrams in the sidebar on the opposite page show how a typical non-feathering hydraulic prop uses engine oil from the propeller governor to change the blades' position when increasing, decreasing or maintaining a pitch setting.
Not depicted in these diagrams is the propeller governor and its function.
Also, the propeller and propeller governor
were overhauled during maintenance unrelated to the engine problem.
Examination of the engine, its fuel pump, injector nozzles, fuel control, oil filter, propeller governor
and vacuum pumps did not reveal any anomalies.
they had lost one engine and then the other...." The witness also reported that after losing both engines they were able to restart one of the engines and then had a discrepancy with the propeller governor
of the running engine.
Now, following the merger with AEP, the company has significantly increased its capabilities, particularly in the area of supporting Lycoming & Continental engines and accessories, including fuel systems, turbo charger components & propeller governors
," the release continued.