Metal found in oil filter

[leo]

Hi everyone,

There was metal in the filter at the last oil change. I spoke with the guys at Lycoming (they were really helpful), put an additional 25 hours on a new filter and sent it to them for analysis. This is what I got back from them:

"Majority of chips were made of low alloy steel, most likely from cam-lobes. Some of these had copper plate along one edge, and had the classic appearance of camshaft chips from a spalled cam lobe. Second-most prevalent chips were made of chill cast iron, from tappets. Also found one chip most likely made of AMS-6450 low alloy steel, probably from oil pressure relief valve spring. One chip made of aluminum alloy, probably from crankcase or accessory housing. One piece of silica grit FOD."

I'm going to have that analysis confirmed of course, but I was wondering what my best option would be if the above diagnostic is correct. The engine is a 18 y.o. Lycoming O360-C4F with over 1400 hours on it. Considering the age and hours, I'm thinking that it's probably best to go with a full overhaul, but would like to know what you guys think.

Thanks for any insight,
Leo

[gbarrier]

Not much choice. Lycoming considers 20 years as TBO along with time. When you open it up you will want to do the whole thing. Once chips start it usually turns into a snowball. Be careful till then.

[aero101]

You gotta open it all up to do the camshaft and followers anyway... May as well do the whole overhaul while disassembled considering age, hours, and I would have some concern where the silica or sand came from?

[Mountain Doctor]

600 hours short of TBO but it is what it is...

The cases have to be split for the camshaft so at that point it seems to me to be most cost effective/time effective/safest is to go with a full rebuild.

Do you live in a moist area back East? Has your plane sit for long periods of time? Short flights not enough to burn off crankcase condensation? Do you run Camguard?

Sorry for all the questions, I'm just trying to benefit from your experience as we have the same engine.

[crbnunit]

I really like the metal analysis. That was very helpful. What company do you use?

[leo]

Thanks to all for the info!

@Mountain Doctor:
I've had the plane for a bit less than 4 years and have put a bit less than 400 hours on it. I don't use Camguard but use the plus version of Aeroshell (100W in summer, 80W in winter). I change the oil quite religiously at 25-30 hours and usually fly for a couple of hours at a time. The root causes are most probably that I wasn't able to fly much in 2013 and that the hangar I have is poorly ventilated and gets flooded after heavy rain.

@crbnunit:
I have the oil analyzed at every oil change by two different labs (it's quite interesting to compare the results, but actually this issue hasn't shown up in the oil analysis). I send the oil filter to Aviation Laboratories. They noticed metal in the filter, but most likely got the type of metal wrong ("AMS# 6414 or 6415"). The metallurgist I spoke to at Lycoming was unconvinced that this was the correct alloy, hence the second analysis of the next filter after 25 more hours, which indeed yielded pretty different results. It was done at Lycoming.

[TomD]

actually this issue hasn't shown up in the oil analysis

I am pretty sure the analysis is done on a spectrophotometer and metal chunks don't show up in the analysis only dissolved or suspended metals would show up on the analysis.

I use Blackstone Labortories for my analysis, btw.

TD

[gbarrier]

Didn't know that Lycoming did that. How does one go about setting it up and what do you ask for?

[leo]

@TomD:
Yes, that is my understanding too. I would have thought though that smaller particles (maybe from increased friction) would show up at the same time as larger ones. Do you know what type of issues oil analysis typically shows?

@gbarrier:
I don't know if Lycoming routinely performs filter analysis, but they are definitely willing to help. In this particular case I came to them with the external lab analysis which they felt was possibly inaccurate, and they offered to take a look at the next filter.

[TomD]

Leo;

Have a look here for info that Blackstone supplies:
http://www.blackstone-labs.com/aircraft.php

[aero101]

Oil analysis will show trend in microscopic iron, alum, iron oxides, steel, etc... It really doesn't mean much unless you're doing it regularly at every oil change so you can watch the trends of the various materials looking for unusual rises with regularity.. Cleaning particulate matter off oil filter into a little pile, analyze for mainly magnetic particles is job of your mechanic. Surprisingly, Lycoming doesn't get real excited until you're getting a good deal more magnetic material then you'd think... Something near 1/2 tsp in 25hrs is getting in area of concern as far as I'm concerned, but I think Lycoming is looking for more like a full tsp? Most engines I've torn down with 1/2 tsp full in filter or screen have shown cam to be going, usually just a couple of lobes, but not near failure mode, so that's what I use as my guide for max metal. In my opinion, the earlier you catch it, the less damage you will find on crankshaft, pistons, pins, etc, etc which translates into less expensive overhaul. You figure with 18 yr old engine you're better then 50% beyond recommended TBO, so you did good. The cam longevity is a matter of luck of the draw and conditions engine operated in. I've seen engines go 3500hr with no metal being made and way beyond calendar TBO. I've also seen factory reman's needed camshaft within 100 hrs of installation. I highly recommend you replace with a NEW factory camshaft, and stay away from the reground ones. I also highly recommend if you're making metal, and overhauling engine, prop should be at least disassembled and cleaned or overhauled. Same for the oil cooler, as you really want to make sure you get all the metal out of everything before starting up that new engine... I don't think Lycoming would be interested in analyzing particles unless you had something unusual or out of ordinary that was being questioned, but you can call their help desk anytime, and they're usually pretty helpful folks!

[leo]

Thanks for all the feedback! I'll let you guys know how it goes.

[leo]

Got the plane down to Moultrie towards the end of June and we pulled a cylinder to look at the camshaft and tappets. Lycoming's diagnostic was spot on: the tappets and the camlobes were showing wear.

I decided to go with a factory remanufactured engine. $28k and two months later we were back in the air, but I'm still working on convincing my wife that this is worthwhile

Here is the remanufactured engine installed:

[Mountain Doctor]

Engine looks good.

$28,000 is a lot of money but less than I would have expected.

O-360 C4F?

Hows the baffling?

[leo]

Yes, O-360 C4F. Lycoming has a significant discount on a remanufactured ($5k) if the engine is a "first run", i.e. if it has never been overhauled, and if it is less than 20 years old. Maybe that means they reuse more parts than they suggest in their advertisements...

Although the baffling looks a little tatty, it is in good condition, still flexible and flush with the cowling, so I chose to keep it.