What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Brass flakes in filter

T

tim2542

Well Known Member
Ive been picking up a small amount of brass fines/flakes in the oil filter on my 300 hr SMOH 0-360 A1A for a while now. Its enough to see, but not any measurable quantity. Oil analysis has copper and aluminum a bit high at 13 and 14 respectively. I had AvLab analyze the filter element to learn exactly what I've got; for $135 I was hoping for part numbers but instead they report the majority of the debris is Brass AMS #4610, with a trace of AMS #4280 aluminum.
Ill call Lycoming in the am and see if I can get some help on what parts are made from AMS#4610, meanwhile I thought Id toss it out and see if anyone has ideas. Im thinking rocker arm or idler gear bushing maybe. Trying to recall where else brass bushings are used other than the connecting rods. All these were sent out for rework at overhaul. Ive got one Slick with an impulse coupler, seems like they have brass bushings but dont recall for sure.
Ideas???
Thanks, Tim
 
If the engine was assembled with the new P/N bronze wrist pin plugs then they may be the source. the aluminum wrist pin plugs loose a significant amount of material over the life of the engine. The new bronze plugs do not wear nearly as much, but they do wear some.

Of course it could be the other sources that you mentioned as well.
 
Piston plugs

Thanks Mike
I have the AEL 14077-1 pin & plug assemblies per SL 13444-1 (which I cannot find now), those plugs appeared to be aluminum, and were pre assembled into the pins. I don't think they are brass.
Tim
 
Close the loop on this one.

So the conclusion to this story. I ve been watching this metal in the filter issue for a while. It was a very small amount, and I kept getting told some small amount is normal, run it! It's not in the automotive world, but I got seduced thinking air cooled Lycosaurus etc. , maybe it's normal. I should have known better. Still I was worried and kept a close eye on it and switched to 25 hr filter inspections.
So I finally pulled the sump to take a look and found the LH Idler shaft loose from the case. Bolt backed out3-4 turns, safety wire broken. The stud/nut still intact. How/why is the question.
I now have the engine stripped to send the case out for repair so I can say pretty conclusively that the oil filter analysis from AvLab is wrong.
They reported the metal to be AMS 4610 brass. Lycoming told me there is no brass in the engine other than fittings. Bronze yes, brass no, and I found no problems with any of the bushings in the engine, or the bearings during disassembly today. The case boss for the idler was fretted and worn, it's apparent the metal I was finding was from the case, and was aluminum, not brass.
I'm glad I followed up on this when I did. I doubt the engine would have ran much longer before the bolt backed completely out. As is I have a case repair to eat, but the plane and pilot are undamaged.
Last flight was over the Sierras, KRNO-KRBL, it wouldn't have been pretty.
So lesson learned, even a small amount of metal in the filter after break-in is cause for alarm.
 
Last edited:
Interesting that the later O-360's use safety wire in that location and the earlier narrow deck O-360's use lockplates...

SL71646__38367.1405447386.1024.1024.jpg


I wonder which version is more reliable.
 
Any chance you have asked AvLab about this? The only reason I ask is because I too use Avlab! I would be curious to hear what they said about the misdiagnosis of the type of metal.
 
The OP said SMOH not where it was overhauled. Is it possible that it was brass due to an aftermarket part? Or one wonders how they tested the metal, XRF?
 
You must log in or register to reply here.
Back
Top