1964-M20E Posted August 25, 2021 Report Posted August 25, 2021 It was interesting flying home Saturday I experienced a governor failure in flight. Run up went well when I cycled the prop before takeoff I was climbing with lower than usual power since I was waiting for a second plane to catch up and the governor was controlling the prop After we were in cruise for a while I noticed that I could not apply full power and the RPMs were going up i.e. losing prop control. I was at a lower power setting than normal since the other plane is slower. As the flight progressed I had to reduce power to control the RPMs, and the governor was doing very little All other engine parameters were good, oil pressure, temp, EGT, CHTs etc. I was able to only maintain 14" of MP and keep the engine below 2700RPM I was ale to complete the flight at 100kts GS After I landed and before shutting down the engine I tried cycling the prop at 1800RM and nothing The engine only has 30SMOH, prop was OH and the governor (PCU5000) was OH, I installed it last year and it only has 130 hours total on it. I checked the prop cable and it was functioning fine I drained the oil and the finger screen was clean, oil filter was clean I removed the governor and the filter gasket was clean as well The governor is being sent back for check and OH Quote
carusoam Posted August 25, 2021 Report Posted August 25, 2021 Bummer… 1) Good news… often in flight, loss of gov control occurs when the oil has just about been fully drained from the case…. 2) mezzo news… not so good, not so bad…. There is an internal seal blocking oil pressure from leaving the shaft behind the prop…. It take removing the prop to see/fix… 3) Possible test to see if the shaft seal is still in there… blow air in through the oil supply line from the govenor… 4) If the shaft seal became cocked in the shaft, it’s a fifty cent aluminum disc… requiring removal of the prop for access… 5) Don’t forget to check the blade stops… these are the things that the blades rest on when the gov goes on hiatus… where they are set is the difference between making enough power for flight, or overspeeding the engine… Good luck… We have only seen a few of these shaft seals come loose over the decade… I had one in my M20C many years ago… Nice work, you handled the situation really well… and reported the details on MS! (Thanks!) PP thoughts only, not a mechanic… Best regards, -a- 1 Quote
hammdo Posted August 25, 2021 Report Posted August 25, 2021 Ck #3 if gov is ok... I went through that already ;o) -Don Quote
carusoam Posted August 26, 2021 Report Posted August 26, 2021 Great pirep for Crystal air at KCHA, AZB! Thanks for sharing the details… Check the age of your engine controls… Having any of them not work properly… MP, RPM, or mixture… can really leave you in a tough spot. Recent experience indicates changing controls with the engine OH as a guide line… Twist controls often get twisted apart when they age…. Best regards, -a- Quote
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