Strange discoloration on flywheel after prop removal

[EXflyer]

Originally Posted by DanH

Wood prop or metal? And what is the streaked material and black material visible through the holes in the first photo? The streaked material seems to be completely filling the big lightening holes

Those are not holes they are in the other part not shown in that picture but does show what was going on. Look at the streaks show in that photo and the center hole clearly oil stains.

[dpansier]

Appears to be Fretting corrosion.

[RV6_flyer]

Originally Posted by dpansier

Appears to be Fretting corrosion.

Agree.

Adding more words for the software so I can post.

[JonJay]

Originally Posted by dpansier

Appears to be Fretting corrosion.

If it is, it should be evident after cleaning: pitting, roughness, surface imperfections, etc....

[Sleepy]

Thanks everyone for your comments. Here some answers to the your questions. As for cleaning and further inspection that will have to wait until I get back from my work trip on Thursday evening.

1. The propeller is a extended hub constant speed Hartzell and was installed new on the RV-4 in 1992.

2. The engine is a Lycoming IO-360-B1E which was originally installed new on a Hiperbibe. It was removed at about a 150 hours, torn down, inspected, rebuilt and subsequently installed on this RV-4 several years later. I am assuming there was an accident with the Hiperbibe, but there is nothing in the logbook stating why the engine was removed.

2. The propeller has not been off the airplane since I bought the aircraft in 2012. According to the logbook, the last time it was removed was for an overhaul and installation of a new AD compliant hub which was in 2008.

3. According to the logbook, the bolts where torqued to 75ft/lbs during the last install. I suspect this is probably accurate as they were a real a bugger to get off last week.

4. The material in the flange of the flywheel is a thick wet grease like material. I assuming oil. The aircraft has always had a small amount of oil resting on the bottom seam of the case just aft of the boss mount for the alternator. Nothing major, just a few drops, but always there. There was no oil on the back of the flywheel or the back of the flange on the crank. My guess is the propeller was leaking a the seal at sometime in the past and the drops of oil are unrelated, but I will need to do some further examination.

I will clean it up and repost some more pictures when I get home tomorrow.

Thanks again for the help.

Scott.

[6 Gun]

I will guess its going to come off as it looks like its part of old oring rubber.
Bob

[lr172]

Looks like oil staining to me. Hard to imagine fretting between the flange and flywheel to be limited like this.

Larry