Oil leak

[Clyde J Davis Jr]

I've owned my 260B since 1989. I had my 3rd engine overhaul performed in 12/14. 20 minutes into the first test flight oil appeared on the windshield. Subsequent tests pointed to the prop governor. It was removed, overhauled and reinstalled with a new gasket. Still oil on the windshield after 20-30 minutes of a flight. During subsequent months prop governor seals were changed and prop seals were changed, all to no avail. Finally I took the plane to an A&P who had worked on the plane previously. He tightened the nuts securing the governor and the problem went away, for all of 6 months. In 10/15 the problem reappeared. Since that time gaskets have been replaced, mounting surfaces have been resurfaced and sealants have been applied. I picked up the plane today after the latest attempt and during the 40 minute flight home oil again appeared om the windshield and oil was on the bottom of the governor.

Does anyone have any suggestions?

[N3322G]

Your information in Pathfinder is marker private or I'd suggest the closest Comanche experienced shop.

If you are stuck with the existing mechanics, you might consider working to identify the true source of the leak with additive and black light or wash the engine and baby powder it. If it happened after O/H, shop doing the re-mount needs to check its work.

Others may contribute add'l ideas.

[Clyde J Davis Jr]

Thanks for the response. We've tried the baby powder route before overhauling the governor and it pointed to the governor.

[William Hughes]

I had a similar issue with my aircraft (250) over the course of about a year. Oil would leak out over the front of the cowling and dribble back toward the windshield, and occasionally spatter on the windscreen, over time. Got it solved eventually and it was a combination of:
1) front crank seal was spinning loose in its housing
2) loose crank-case through bolts (I could spin two of them easily with my fingers!)
3) loose oil hose clamps

Item two probably had some sort of causal relationship with item one. Although we checked it last after doing a bunch of other work. Just didn't think to check the crank case bolts as it never occurred to anyone that those could be loose. Might be worth a check...

[Clarence Beintema]

I've seen a similar situation with a prop governor before, it was a case of the installer used internal star lock washers which had a larger outside diameter which was catching on the counter bored holes in the governor. Adding a smaller diameter split lock washer and torquing to 205 inch pounds cure the problem.

Clarence