Hartzell CS prop has leak at crankshaft flange

[jgbmo]

I recently made the first flight of my new RV-7 with a Lycoming IO360-A1A, Hartzell Scimitar CS prop, and MT prop governor. I had overhauled the engine myself with a certified crank. The prop had been overhauled by a prop shop, and the governor was new (purchased from Van's).

After exiting the cockpit I noticed oil had streamed down the front and inside cowling. There was also a small amount of oil in the back of prop blades. The crank seal on the front of the engine was dry. I pulled the prop and replaced the O-ring in the prop hub. I then made a second flight and had more leakage.

I am stumped. Any suggestions would be appreciated!

 

[airguy]

Pull it apart and clean it well - the re-assemble. Ground run it for about 2 minutes and cycle the prop a couple times, then inspect. That will tell you for sure where the leak is coming from without goobering everything up. A little baby powder dusted on the dry surfaces might assist.

 

[jgbmo]

I will do that. Thank you!

 

[lr172]

If the prop has been sitting for a few years and especially if it was built during the time they used aeroshell 6, it is likely that some of the oil has separated out from the grease and that is what is coming past the hub o rings; They will hold in grease, but not hold in oil. My prop was built with aeroshell 6 grease and it slung oil from the hub seals for over 100 hours. This is why they stopped using #6. The reformulated version has a serious problem with separation.

Not sure this applies to your case. I only had oil streaks on the back side of the prop blades an oil streaks down the top cowl and windshield. Nothing much dripping.

Larry

 

[Ralph Inkster]

A extreme suggestion, but...
Some props have indexing studs with one prop mounting hole slightly larger than others. If the prop is mounted but not clocked to that hole alignment, the prop will not sit flat to the crank flange & will never seal.
Again, extreme, but I've seen one engine/prop put together like this...