I arrived at the hangar this afternoon to find a small (CD size) patch of oil below the aircraft. It took a while to find the cause as I started by assuming that last weeks oil and filter change were responsible.

Finally, with the telephone help of my friendly engineer, I tracked it the oil return pipe from the cylinder head on the starboard rear cylinder which has been chafing on the plastic cowling. Yes, it seems plastic cuts aluminium - see photos.

This particular pipe is visible from the oil filler hatch but to see the area where it is chafing requires cowl removal as it's tucked under the cylinder.

Although the amount leaking was small it clearly had potential to spoil my day on a long flight, especially since I don't generally check the oil while hot between same day flights. I shall in future.

I'll be looking at replacement/repair today but it needs some way to separate the pipe from the baffle to prevent a recurrence. I also need a good look at the others which will require a little more disassembly.

This slipped through the last 100 hour/annual in February at 265 hours. It's now 301 hours on the tacho.

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