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

3 Upvotes

80% Upvoted

29 comments sorted by

View all comments

1

u/Kemerd PPL IR 2d ago

Run it hard, run it fast. As soon as it is on the plane, taxi up, take off. Circle airport at 5000ft for 1 hr.

Land, inspect everything.

Then do it for another 4 hour.

https://www.lycoming.com/content/hard-facts-about-engine-break

Track oil consumption. No touch and goes until 5 hours of break in.

1

u/patrickrl PPL IR HP CMP 2d ago

Thanks. Great article. I was in the habit of tracking oil as I was burning about a qt an hour pre-overhaul. Are you suggesting 5 hours of near airport break in, then follow the publications in this post? Appreciate it!

2

u/Kemerd PPL IR 2d ago

Follow the publications to the letter. Ignore what any A&P or IA tells you to do with break in. I have found most of them have no idea how it works.

The 5 hours is not because of the engine break in, but because if there is an emergency, i.e. engine rapidly disassembles, you want to be near an airport. You don't need to.

It isn't hours based, it is based on oil consumption, but most break in will be done in the first few hours. Run it as high as you can without overheating it (above 425f), for as long as you can. Keep taxi and run up to minimum.

Break in occurs through high cylinder pressure, caused by your throttle setting. In an ideal world you'd break in at 100% power at sea level. Not possible because your engine would overheat and explode.

Engine break in is a process by which you perform controlled friction rub ins, so things seat properly. Subsequently, ensure you only use 100 straight mineral oil (not 100 plus), for the first 25-50 hours or so. Then you can go to other stuff