Oil analysis - corrosion detection

[FlyDave]

I'm looking at a plane that has around 1500 hours on the engine. It flew around 105 hrs this year, 85 in 2012, 77 in 2011 and before that less than 20 per year for the previous 9 years. It was hangared near the Texas/Oklahoma border.

Compressions are consistently around mid 70's at annual.

I have previous oil analysis for this engine from 1999, 2000, 2006 and 2008 and all state that "Sample appears Normal". So I have somewhat of a baseline to gauge the current oil analysis against.

What I'm wondering is, will oil analysis reveal any indication of corrosion? If so, what would I look for in the oil analysis to determine this?

 

Thanks,

 

Dave

[Cruiser]

Iron

[FlyDave]

OK - Iron. Anything else?

What are acceptable parameters for each?

[Jerry 5TJ]

Can you tell from an oil analysis if the iron is from wear or from corrosion?

 

Here is a sample report from the Blackstone web site:

 

http://www.blackstone-labs.com/aircraft-sample-report-3.php

 

which does show iron as one of the sampled elements, of course.

This report was from a TIO-540 running >100 hours per year

and it shows the iron content rising significantly in a few samples prompting a borescope exam

and a cylinder replacement.   

 

Is there a detectable pattern in iron content from a seldom-run engine 

identifying corrosion versus iron from wear?

 

 

 

[FlyDave]

Good question Jerry!

Anyone.....Anyone...

[Jamie]

avweb article on oil analysis:http://www.avweb.com/news/maint/185087-1.html?redirected=1

 

good one on filter + oil analysis: http://www.avweb.com/news/savvyaviator/190242-1.html?redirected=1

[Marauder]

I'm looking at a plane that has around 1500 hours on the engine. It flew around 105 hrs this year, 85 in 2012, 77 in 2011 and before that less than 20 per year for the previous 9 years. It was hangared near the Texas/Oklahoma border.

Compressions are consistently around mid 70's at annual.

I have previous oil analysis for this engine from 1999, 2000, 2006 and 2008 and all state that "Sample appears Normal". So I have somewhat of a baseline to gauge the current oil analysis against.

What I'm wondering is, will oil analysis reveal any indication of corrosion? If so, what would I look for in the oil analysis to determine this?

Thanks,

Dave

Dave -- this is a tough call. If there was going to be doom and gloom after flying 20 or less hours per year, I would expect problems to have started showing up since 2011. The reality is that the uncertainty is the condition of the cam. The fact it flew 3 years without a problem is good. The problem is that if the cam is corroded, you probably won't make it to the 2000 TBO recommendation (or beyond).

I would treat it as a 1500 hour engine that will need to be rebuilt within 5 years (assuming a 100 per year flying) and make sure the price reflects this.

[jetdriven]

I'd price it as runout.  I'm serious assign zero value to the engine, because it only has core value. Anything over 100 PPM iron Lycoming considers "elevated" but their documents havent been updated since 1971.   FWIW our A3B6D engine started coming apart with 3 spalled lifters and a ruined camshaft, the iron was 99 PPM in 50 hours.  Now, our new Lycoming factory engine has 300 PPM of iron in 50 hours and the factory is playing dumb.

[OR75]

if metal levels are normal, compressions are good and it has been run normally past 3 years, i personally. doubt it will all of a sudden fail. i see it go to TBO.

maybe a borescope inspection can help you

[jetdriven]

if metal levels are normal, compressions are good and it has been run normally past 3 years, i personally. doubt it will all of a sudden fail. i see it go to TBO.

maybe a borescope inspection can help you

Let me very clear here. If a Lycoming non-roller engine sits for more than 30 days without flying, corrosion forms on the lifter surfaces.  If this happens very many times, it will not make TBO. The boards here are full of pilots who faced a sudden engine overhaul or had a prop strike inspection and opened it up to find extensive damage.  Bob Bellville  and Scott being the latest, and their engines were flown often.  I personally know 6 or 7 pilots in the past 3 years who have had this happen, plus ourselves.

 

Ours was flown 100 hours per hear for ten years, then 75, then 50, then 30.  then we put 250 hours on it in a single year and it ran great, a real sweetheart.  Then, boom,  a half-teaspoon full of metal and 99 PPM iron in the oil. The last Blackstone oil report, "This IO-360 is aging very well and looks great".

[DS1980]

Let me very clear here. If a Lycoming non-roller engine sits for more than 30 days without flying, corrosion forms on the lifter surfaces.  If this happens very many times, it will not make TBO. The boards here are full of pilots who faced a sudden engine overhaul or had a prop strike inspection and opened it up to find extensive damage.  Bob Bellville  and Scott being the latest, and their engines were flown often.

Is there a known cause for these frequently flown engines having corrosion problems? Do you know if Bob or Scott were using Camguard?

 

Oh and agree as assigning only core value to the engine. Iron isn't the only thing on the oil analysis that I don't like.

[aaronk25]

Let me very clear here. If a Lycoming non-roller engine sits for more than 30 days without flying, corrosion forms on the lifter surfaces. If this happens very many times, it will not make TBO. The boards here are full of pilots who faced a sudden engine overhaul or had a prop strike inspection and opened it up to find extensive damage. Bob Bellville and Scott being the latest, and their engines were flown often. I personally know 6 or 7 pilots in the past 3 years who have had this happen, plus ourselves.

Ours was flown 100 hours per hear for ten years, then 75, then 50, then 30. then we put 250 hours on it in a single year and it ran great, a real sweetheart. Then, boom, a half-teaspoon full of metal and 99 PPM iron in the oil. The last Blackstone oil report, "This IO-360 is aging very well and looks great".

He is spot on here! We don't wear them out we rust them out .

[OR75]

He is spot on here! We don't wear them out we rust them out .

ok. but i still don't see an obvious correlation.

[Bob_Belville]

My engine was run on Aeroshell 100 (not plus) only for its 700 hours. Analysis reports were "normal". The prop strike  (minor?) was the only reason the engine was torn down. Crank, case and cylinders all were fine but cam was pitted and lifter caps were pitted and spalling. I found out today the crank will be ground .003 and a gear at the rear of the case that has a crack will be replaced. That's the first I had heard about the gear, not sure what to make of that, Tim thought the prop strike might have caused it.?  I will visit the engine shop Tuesday and hope to have a better picture of what went on with this 700 hours/12 year old FRM. But to correct Byron, this plane did have some inactive time in the past, particularly in the 2 years before I got it.

 

FWIW, I averaged 250 hours per year on a '66E that I owned for 11 years. I swallowed an exhaust valve - 1 week downtime to replace that cylinder - but otherwise uneventful. In hindsight I blame the valve on running the plane in the "red zone" we didn't know any better in the '70s and we had only a single EGT probe which we used to run 25 ROP.

[DS1980]

ok. but i still don't see an obvious correlation.

What correlation is being referred? The correlation between sitting an engine and iron?

[jetdriven]

I have found no correlation in iron on oil analysis and lifter corrosion, except if its over 30 PPM/50hr, its possible. It starts out too small to be noticed and the only way to know is metal in the filter. The only way to be sure of that is to wash the filter in mineral spirits and strain it through a coffee filter. Any circular or irregular-shaped flakes indicates lifter pieces. Hair-like particles are from the cam.  Grainy sand particles are from either advanced lifter failure or from rings/cylinders.

 

This is 25 hours worth of metal...

 

 

[Bob - S50]

Just a point of reference for you.

 

First, Mike Busch says compression checks are not good indicators of engine condition.  The best thing to do would be to do a borescope.  It won't tell you about the cam or lifters, but it will tell you about the cylinders and valves.

 

Second, our group bought a J that sat in a hangar in northern CA for 10 years.  The engine had about 800 hours on it.  The first oil analysis we did had almost every measure in the red, but we expected that from surface corrosion.  We changed the oil again at 25 hours and everything was in the green.  We changed again at 25 hours and it was all still in the green.  We now plan to change the oil every 50 hours.

 

Bob

[FlyDave]

Can you successfully evaluate the cam and lifters on a Lycoming TIO-540 by removing a few cylinders during a prebuy?

If this costs an additional ~$500 and can reveal an engine that is going down the tubes it would be well worth it.

[38Blackfin]

 

This is 25 hours worth of metal...

 

Wow...this is the most metal I've ever seen from an engine still in service - I'm a long time diesel guy, we have similar issues and conversations. But that's a crazy amount of metal- there'd be no conversation after that -

Randy

[carusoam]

Byron,

Holy cow!

That's not a measure in ppm... Or even parts per thousand

Grams/liter maybe.

What's next on the list, identify the missing engine part that has given it's life up for this?

My guess... A roller lifter isn't working as advertised ...

Maybe it's simply the lifter that needs to be replaced, not the cam....

Best regards,

-a-

[jetdriven]

Yes that is cam and lifter metal from the old engine

[Cruiser]

from the comments on this thread it seems lilke:

 

1. Oil analysis is not predictive of cam or lifter pitting

2. Normal to higher hours of usage AFTER an engine has been sitting or little used does not mean problems will not develop

3. Cam and lifter spalling can develop quickly without symptoms until metal is found in the filters/screen.

4. Regardless of the number of hours flown, rust can form and cause damage if an engine sits unused in as lilttle as 5 to 10 days.

5. Cam and lifter pitting may not be noticed for up to two or more years after prolonged periods of idle or low use.

6. Rust will eventually cause cam and lifter pitting.

[carusoam]

Phhhwew, I get it, now!

Thanks, Jim.

Best regards,

-a-

[pirate]

A friend had his warrior overhauled, flew it once twice a week about 100 hours per year. 5th year his cam/ lifters went south, he had to do another overhaul.

Another friend has many airplanes and one of them he has owned since new a 69 180, about 900 hours never overhauled flys on average once month about 20-25 hours a year and never a problem.

Both airplanes based in IL, the warrior in a cold drafty hanger and the 180 always in a large heated hangar. I wonder if storage also has something to do with it................

[aaronk25]

A friend had his warrior overhauled, flew it once twice a week about 100 hours per year. 5th year his cam/ lifters went south, he had to do another overhaul.

Another friend has many airplanes and one of them he has owned since new a 69 180, about 900 hours never overhauled flys on average once month about 20-25 hours a year and never a problem.

Both airplanes based in IL, the warrior in a cold drafty hanger and the 180 always in a large heated hangar. I wonder if storage also has something to do with it................

Wonder if the one with no issues ran 100w and the other a lighter or semi-syn blend?