As they say, things can always get worse. On the heels of working a cowl flap motor issue which is now in overhaul, I may have one even worse.
Back story: In Dec, I had a momentary buzz from the prop while in the pattern. It happened very quickly before I could really notice any other indications. I chalked it up to turbulence and being that it was my last pattern, landed without further incident. A week later, shortly after takeoff and turning to downwind, it buzzed again and the RPM spiked to 2800. I turned base and landed. My A&P removed the prop governor and sent it to Palm Beach to be overhauled. I flew 4 flights since then without incident. However, on pre-flight checks for the 5th flight, it would not cycle. I tried numerous times at 1700 and 1800 RPM. Further, with my A&P on board, we tried several times at even higher RPM and still wouldn't cycle. He removed the prop governor again and sent it back to the repair facility. They suspected a sticky valve, replaced, bench-tested good and sent back. After re-installation, it still will not cycle. Working with the Palm Beach facility, they've run several tests to assure oil is flowing to the governor, but it appears pressure to the governor from the crankshaft is fairly low. The current assessment is that the crankshaft bearing controlling pressure to the governor is worn/failed. Worse, it requires an overhaul as a result. His telephone consult with Don George Aircraft in Orlando confirmed the same.
The engine is a Continental TSIO 360 MB with about 1000 hr SMOH. It has normal compressions, oil pressure and runs smooth. My last oil change/sample was clean. I baby the prop the way my instructor (previous owner) taught me. I don't understand why/how it could have failed.
What could we be missing? Anyone else experience a similar issue? I appreciate any advice before spending $50,000 on an otherwise perfectly running engine.