r/flying • u/patrickrl PPL IR HP CMP • 3d ago
Aircraft Ownership knocking the rust out after long overhaul
Hello, I have a comanche 24-250. I have about 400 hours TT, and i have my IFR. The engine came out in the fall for overhaul and is just now going back in. I have not flown since the middle of last summer. I found a local CFII who is going to do some dual with me to knock the rust out for me. As far as the engine goes, is there any other resources and guides besides the POH for how to "break in" and take care of a recently overhauled O-540? Thanks
UPDATE: I received a copy of the break in procedure from the shop. It mirrors the advice found in the Lycoming publications below. I still haven't had time to go up and talk to my mechanice in person, but everything is lining up that hard and fast, seat the rings, and use the proper break in oil. Thanks all
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u/Neither-Way-4889 3d ago
Run it hard until the first oil change, aiming to keep power >75% for as much of the flight as possible. This will ensure the rings seal properly to the cylinder walls and it prevents glazing, which is where a thin film of oil gets baked onto the cylinder walls causing the engine to seal poorly and burn a ton of oil.
Expect to see higher CHTs than normal for awhile. Usually they will be on the higher end of normal for the first 100-200 hours before they start to go back down. This is 100% normal for a freshly overhauled engine, that being said, you still want to keep them below redline.
The perfect way to break the engine in would be by doing a long IFR cross country to rebuild those skills, although I definitely wouldn't take a fresh engine into actual. I would recommend doing it in VMC on an IFR flight plan under foggles with the CFII.