Oil pan leak problem

This Rotax 912uls has been running for 919 hours, again this has never happened before

Those two bolts/plugs you have circled might need new crush washers and retorquing.

Hi Sanghelious,

People, in aviation, get very excited over the slightest sign of a leak, forgetting that almost all engines that have significant service time will have a small leak/weep or two without any significant effect on performance or safety.

When you find a leak, seems to me the questions you need to ask are; - 

 # Does the leak signify a deeper problem? In this case I think thats unlikly.

 # Is there a safety issue (fire, running out of oil, etc)? Again I don't think so

 # Is the leak such that I need to do something mechanical (ie replace a part, etc)? In this case, I suspect the leak is more of an annoyance than a significant problem (only you/your mechanical advisors can make this judgement). If so a good clean every 50-100 hrs may all that is needed.

Why not try James Ott's suggestions (above). Cheap/quick & easy to do and may just solve your problem.  😈

Hi all...first, the oil "plug" on the oil pump is the retaining bolt for the oil pump regulator.  (internal spring and ball)  This part is sealed by the plug having a conical seat of the plug bolt, no gasket should be used.  The centre part circled is just a retaining casting for the oil plug to attach your safety wire to.  It has no contact to the internal oil.  Oil at that part is just likely weepage from somewhere on the lower part of the engine.  Perhaps even just oil weeping from the oil filter gasket from the last oil change.  The plug in the bottom of the engine has a gasket, perhaps that is leaking but it is doubtful. 

The lower area of the engine is not really an oil pan as this is a dry sump engine, all the oil is held in the oil tank and circulated.  I would suggest you look for areas like the oil line fittings, the oil line itself perhaps at the ends.  The likelihood that you have a leak at the crankcase parting line is very low as it is sealed with a Loctite sealant.  Sean is on the right path, look to what has changed since you did any maintenance or service on the engine. 

Perhaps take a page from Roger Lee and clean up the oil trace and track with some foot power dusting the lower area to see if this is not coming from somewhere else first.  

Cheers

Many times oil seepage comes from another place because of the air flow during a flight or it seeps down past the origin spot to another area. Double check under the gearbox in between the oil pump and the bottom edge of the gearbox. I've seen a number of the oozing there and the oil migrates to lower areas. If that isn't it then clean it up and spary the foot powder on it. It will then show the oozing oil like a red flag. It could also come from the oil filter seal. Some very minor oozing is not worth the trouble at times.  

Good Diagnostics is always a good idea.