O-320 started leaking at the lift ring

[Subsonic]

I never liked the look of the little inverted U-strap lift point on my O-320. My engine started leaking there a couple weeks ago, so on advice of my IA, we re-torqued all those bolts along the crankcase top centerline to spec. Every one of them moved a little. The one with the U-strap on it moved the most. Maybe 1/3 turn (120 degrees) to come up to spec.

I read things about "fretting" that concern me, but I don't want to invent a problem that doesn't exist. Maybe the bolts weren't sealed properly when it was rebuilt? Only about 300 hours since rebuild.

What is the best way to seal them now?

 

[Gilbert Pierce]

When I had that problem I coated the inside of the bolt hole with Aviation Non-hardening Permatex and replaced the bolt. That stopped the seep.

 

[Jim]

Hi,

There was some poor advice floating around mentioning using that ring to lift the plane for a bungee change. Any chance that was done?

 

[Troy Hamon]

It is my impression, based on my experience with a couple of engines, that some of the case seal materials that are approved for use don't set up as well or as quickly as the old thread and loctite solution, and consequently can result in needing to retorque the case bolts.

Merely my impression. Check them again in 25 hours. Eventually they settle in if your experience is similar to mine.

 

[Steve Pierce]

I remove the leaking bolt, clean it and the hole and then coat the bolt with Aviation Permatex and reinstall. Usually works great.

 

[Subsonic]

Hi,

There was some poor advice floating around mentioning using that ring to lift the plane for a bungee change. Any chance that was done?

No. But I can't rule out a shop that did an annual inspection and oil change for me a couple years ago didn't use that lift point for some reason. I found a clevis attached to the U-strap when I got back to my hangar.

 

[Subsonic]

I remove the leaking bolt, clean it and the hole and then coat the bolt with Aviation Permatex and reinstall. Usually works great.

Thanks Steve. That's what I was looking for.