elevated aluminum on 300 hr 912ULS

leak test all good 79-80

boroscope small amount of scuffing in cylinder 3 but not significant according to A&P

will change oil in 25 hrs and resend a sample

Alan

You shouldn't see any scuffing on the cylinders, as this is very unusual given that they are Nikasil-coated. These cylinders are extremely durable, and scoring or scuffing on Nikasil cylinder walls is not common.

We’ve seen cylinders with over 8,000 hours on them that are still within spec!

If possible, upload photos of the scuffing and definitely send another oil sample to Blackstone. They are a reputable company that we recommend since they are familiar with Rotax engines.

photos of cylinder 3

also these are the spark plugs

very cold here

front cylinders seem to be running colder despite winterization plates

Alan

Alan,

The thrust side of the piston #3 faces up. So, if the photos are oriented properly then the position of the scuffing is on the thrust side as would be expected. It does look minor at this point but consider investigating further by sending these photos to a major Rotax service center for their opinion. If you address this now you may get some help from Rotax, and the fix is not that big of a deal at this point.  Remember, you get an oil analysis to head off problems early, not so that you can live with them until they get worse.  Feel good about that fact the oil report did its job.

This scuffing can be the result of a lack of lubrication, overheating, of even a bad wrist pin that is not rotating freely.  This can happen on cold startup. Burping the engine also pre-lubricates it, so do it happily knowing you are doing the engine some good. In colder climates it’s is especially important to warm the engine up slowly and at low RPM as outlined in the operating manual.  Not only is the oil more viscus when cold, but also the piston can initially heat and expand more rapidly than the cylinder bore, leaving less room for oil until everything is up to temp.