Hello there, this is my first post, and I'm writing with a constant speed propeller problem that no one has been able to resolve...Have been trying to fix the issue for one year now, and my mechanic is talking to Lycoming, McCauley, engine overhaul shop, etc...
I own a 1979 Cessna 182 Turbo retractable with a Lycoming O 540 engine and a 3 bladed McCauley propeller, 920 SMOH, 300 hours since Top overhaul, 3900 total hours.
In 2015 (before the top overhaul) , the propeller governor went off line in climb-out and the propeller behaved like a fixed pitched propeller. The symptom stopped 10 minutes later. The governor was removed, sent out for testing, and returned without an issue. Subsequently, the same thing happened a year later, and then it happened more frequently. Now it happens every second or third flight and then the propeller returns to behaving normal eventually. The intermittent nature seems to make it so difficult to diagnose.
The prop cycling on the ground is normal, the propeller does not over-speed ever, and when it acts like a fixed pitch propeller, moving the prop control does nothing.
The following was done, to no avail:
- used a loaner governor, same problem...than installed new McCauley governor..same problem
- checked all oil galleries for obstructions: Free and clear
- Overhauled propeller..
- Checked if the blades move correctly..they do
- Checked plug in crankshaft that closes off one side of oil flow for constant speed prop: It is securely in its place
- Oil pressure is always nicely in the green...however, I have the old gauge that does not give me actual psi readings.
- Oil temperatures are good
- CHTs great
- No metal in oil filter or oil analyses
One of the theories is that I have a moving (not spun) front bearing that moves fore and aft in a type of a groove intermittently, so that the two oil openings do not line up exactly, ... just enough to cut off some of the oil flow which will reduce oil pressure to the point that it cannot activate the governor. It clearly does not cut off oil altogether, as my engine would seize then.
Now I'm facing a tear-down or an engine overhaul. I'm not flying due to the fear that a spun bearing might be imminent...on the other hand, I'm afraid that, once the case is open, we'll find nothing wrong with the bearing...I'm truly at my wit's end...and hoping that someone with a fresh view can provide some great insight.
Thank you much for reading my post.
1greenmachine