Cotter pin in oil pickup screen!

Changed oil today and checked the pickup screen because I hadn't done it in quite awhile. UGH! Found two pieces of what appear to be a small broken cotter pin. Oil filter looked very clean upon cutting open and inspection. Engine has been running fine and didn't see anything unusual in last borescope inspection 6 months ago although I was mostly looking at valves. Last oil analysis was normal as well.

Couldn't think of how in the world that would get in there but it dawned on me on drive home - aren't the drive gears on p-mags secured with small cotter pins?
I also have a B n C 8 amp backup alternator on the accessory case. Can't remember if that uses a cotter pin or not.

I will pull pmags and have a look. Any other possible sources for this? What else should be done before next flight?

Thanks
Erich

That's where I would look.... at the mags. And check for undersized dia. cotter pin used.

Check with who built your engine? Not even cool....

This is an ongoing problem and it can do some real damage. EMag needs to get proactive with this and issue a service alert of some kind.
http://www.emagair.com/service-notes/
You really need to pull the sump at a minimum and make sure the idler post(s) are secure and you have no damaged gears. I found my idler gear post bolts loose, safety wire broken, cam and crank gear damaged after I lost 10 psi oil pressure and a cotter key in the sump. The idler post bolts were knocked loose when the cotter passed through the gears, allowing the idler post to work in its boss and eventually the safety wire broke, the bolts backed out and the post came partially out of the case boss allowing oil pressure to escape. So a complete tear down and case repair was needed on a 300 hr engine.
I also know of another who found loose bolts after a cotter key came out. This individual has had two episodes of this. He simply bolted his back down not believing the case boss for the idler was worn enough to matter.
Once back together use the slick part number cotter. It's the right size and stainless steel. Then make sure it's crimped down and can't move at all.
Good luck, I hope your cotter pins in the sump are not mashed, if so I would pull the sump and probably the accessory case. Don't forget the crank gear retaining bolt and dowel.
Tim Andres

I see now there was a very similar thread last year:

http://www.vansairforce.com/community/showthread.php?t=122810&highlight=Cotter+pin+pieces

The difference here is that I have pmags and per Tim below, there is a history of the wrong size cotter pin being used to secure the drive gear on these.

Everyone with pmags, please make yourself aware of the Pmag service note on their website and replace your cotter pins if appropriate. I didn't get the memo and am paying the price now!

Erich

Thanks for this thread. While I have inspected my PMAG each year per the manual, I have never given the cotter pin a second thought. I decided to pull mine again today to look it over. I found a much smaller cotter pin than currently recommend and it was loose as well. It was all there however and had no signs of letting go any time soon.

Anyway I changed it to the right size which was a pain in the rear! It is almost impossible to get the right size pin in there due to the design of the gear and the fact that the PMAG shaft is drilled a bit off center.

Getting this pin in takes a bit of patience and the right brass tools to prevent damage to the pin and the gear. You also have to be very careful to not damage the PMAG with excessive force to the shaft.

Brantel said:

Thanks for this thread. While I have inspected my PMAG each year per the manual, I have never given the cotter pin a second thought. I decided to pull mine again today to look it over. I found a much smaller cotter pin than currently recommend and it was loose as well. It was all there however and had no signs of letting go any time soon.

Anyway I changed it to the right size which was a pain in the rear! It is almost impossible to get the right size pin in there due to the design of the gear and the fact that the PMAG shaft is drilled a bit off center.

Getting this pin in takes a bit of patience and the right brass tools to prevent damage to the pin and the gear. You also have to be very careful to not damage the PMAG with excessive force to the shaft.

Click to expand...

Check the bends in the Slick part... would that have helped?

Helped? Yes but to get one in there, it must be bent like that anyway.

I changed mine out tonight. The old one measured about 0.055 and was loose in the hole. The new one is about 50% larger and is a tight fit.

I'll reinstall the pMag at lunch tomorrow, so long as work doesn't get in the way.