Oil leak aft section

Hi Chris

If this engine had someone remove the rear housing (flywheel and housing to access the sprag clutch) I must suggest that should you not find anything else consider that the oils seal may be compromised or the bolt at the 9 o'clock position that retains it inside was not put on with loctite.  (see Heavy Maintenance Manual) 

While your at it given that the engine was out recently as I understand,  perhaps carry out a crankcase pressure check.  (see your Installation manual) If you have a blockage on your oil return line from the crankcase to the oil tank excess internal pressure can build up and push the oil seal out behind the flywheel.  This is not the same as oil pressure at your oil pump, this is the internal pressure of the blow-by gases that drives the oil back to the oil tank.  Sometimes a fouled line with debris at the exist fitting on the crankcase can cause the same problem.  

Good luck, hope you find it is an easy fix. 

Cheers

Once again I appreciate the feedback from the group.

Let me clarify first that the amount of oil leaked is not in the liters. I would estimate one or two tablespoons probably closer to the lower number. But as previously eluded, a little oil can make quite a mess. In any case, this is to me too much oil to suddenly leak and warrants investigation. If something like this occasionally happens on these engines (my experience is with Lycoming and Continental engines) then that feedback would be appreciated.

I drained 120 ml from the tank and than was enough to go from maybe 3ish mm from the top of the flat to a little over half. So not much. I would think though that if the tank is overfilled the oil would just spew out through the tank's vent line.

The engine was completely dismantled and put together by an iRMT Repair Center. I am keeping a close eye on the aft oil seal and the 9 o'clock screw but on the last 1/2 hour run I saw no leaked oil (I saw a previous posting on this on the forum).

Found the procedure to perform the crankcase pressure test. I do have a pressure gage but need to find a fitting to connect the magnetic plug port to the gage.

Best Regards,

Chris

Actually found an M12x1.5 to 5/16" barbed hose fitting at Amazon so I am good to go.

BTW, something interesting caught my eye on the Installation Manual while reading about the lubrication system. The manual states that if no oil thermostat is used (I don't have one) and the conditions are cold (last flight was a little cold, this is Florida so not too bad) the oil can congeal during descent. I know that during the last few flights I did the oil temp got down to close to 120F during descent. Could this be an issue?

Chris

120F is pretty cool for the oil temp – not enough to "congeal", ofc, but it will certainly be more viscous down there and you would expect to see higher oil pressures as a result.

I have been ground running the engine now for about an hour and no leaks. I am getting the fitting today to do the crankcase pressure test and if it passes I will fly it around the field a little to make sure it's ok. 

Still cautiously investigating but getting closer to a conclusion that this was not something serious like a crack.

Regards,

Chris