Overhaul? Lead flakes in oil - interpretation please

I have a 1972 Cessna 172 with a Lycoming 0-320-E2D engine and it runs
beautifully. It is on UK private category.
The engine is "original" and total time is about 2800 hours.
The engine had a thorough top overhaul quite a few years ago, maybe
around 1500 hours (new pistons etc) and has no problems with
compression, oil consumption, vibration or indeed anything at all. It
is well looked after.
Now the but.....
At its last annual (Christmas) some metal particles were found in the
oil filter.
--------------
The lab report says:
Filter section weight 397 milligrams
Major: - lead flakes measuring 0.1mm across
Minor: - blank
Traces: - Aluminium alloys - corroded fragments measuring up to 1.6 x
0.5mm
Iron - 0.5%
Nickel - 0.5%
Chromium steel such as sae8617,8620 or 8740 flakes measuring up to
0.9mm across
Iron - A low alloy carbon steel with no significant alloying
constituents such as sae 1010 slivers measuring up to 0.9 x 0.3mm
Miscellaneous - mainly fine particles.
--------------
I think it now means a complete overhaul to zero time.
The choice seems to be:
a) Factory Zero timed engine
b) Factory overhauled engine
c) Have my own engine worked on

What are your views about which way to go with this?

It is awfully tempting to keep the plane running and cut open the new
oil filter at, say, 20hours and see if there are any more particles.
As I said, compressions, oil pressure, power etc. are all good.

Maybe my greatest fear is that if I keep it flying, there may be
damage caused to the crankshaft or something which causes a big price
increase at overhaul due to the part being rejected.

Any advice / comments greatly appreciated.

Les

On 5 Feb 2004 04:26:18 -0800, (Les Sullivan)
wrote:

What are your views about which way to go with this?

For an opinion from someone with many years of experience in the business
and an excellent reputation (at least in the US), I would recommend you
contact Howard Fenton at:

SECOND OilPINION
7820 So. 70th East Ave.
Tulsa, OK 74133 (USA) 918/492-5844

I believe he charges $15 for a second opinion on the oil analysis; and can
also do a filter analysis (if you still have the sample and think it should
be repeated) for another $15.

Probably a worthwhile investment given the cost of an overhaul.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

(Les Sullivan) wrote:
I have a 1972 Cessna 172 with a Lycoming 0-320-E2D engine and it runs
beautifully. It is on UK private category.
The engine is "original" and total time is about 2800 hours.
The engine had a thorough top overhaul quite a few years ago, maybe
around 1500 hours (new pistons etc) and has no problems with
compression, oil consumption, vibration or indeed anything at all. It
is well looked after.
Now the but.....
At its last annual (Christmas) some metal particles were found in the
oil filter.

I agree with your conclusion, which is that the engine has no life left
in it. If I understand properly, the engine left the factory 32 years
and 2800 hours ago and has never been overhauled except to change
cylinders? You're way beyond TBO by both calendar and hour limits.

I don't know how the regs work in the UK, but I assume they're the same
as here, in as much as TBO is not regulatory for private operations.
Still, the metal doesn't know what country it's registered in. I'm not
terribly concerned about running an engine past TBO, but if you're got
2800 hours in 32 years, that's averaging less than 100 hours a year,
which raises a warning flag in my mind about internal rust and
corrision. Now that you're producing metal chips, I think your best bet
is to be happy that you got your money's worth and more out of the
original engine.

a) Factory Zero timed engine
b) Factory overhauled engine
c) Have my own engine worked on

What are your views about which way to go with this?

My pesonal opinion is that a Factory zero time engine is the way to go.
It is also the most expensive of the alternatives you listed. I cannot
offer any cohesive argument to back up my suggestion, it's just my
personal opinion. I'm sure other people will give you other (equally
valid) opinions.

It is awfully tempting to keep the plane running and cut open the new
oil filter at, say, 20hours and see if there are any more particles.
As I said, compressions, oil pressure, power etc. are all good.

For what it's worth, when my club had an engine that started producing
metal in the oil filter, we did exactly that (although I think we did it
at 10 hours). We got more metal. We were told (by Mattituck) that
given the type of metal and the shape of the particles, source had to be
wrist pins rubbing on the cylinder walls. Encouraged by the thought
that we might get out of this with just a top overhaul, we had all 4
cylinders pulled. There was no visible damage to any of the wrist pins
or cylinder walls. We had the oil pump pulled, and again there was no
visible damage there.

In our case, we had a bit of a dilema, because the engine was much newer
(about 1300 SMOH) so there was a lot of value left in it and we were
very much interested in avoiding having to overhaul or replace it if
possible. With 32 years and 2800 hours on yours, you should have no
such thoughts. What we ended up doing was wasting a lot of money and
time doing diagnostic work that ended up for naught. It's a crapshoot.
Ultimately, we replaced the engine.

Maybe my greatest fear is that if I keep it flying, there may be
damage caused to the crankshaft or something which causes a big price
increase at overhaul due to the part being rejected.

My fear would be that you're chewing up some critical bearing and you'll
have a catastrophic engine failure in flight. A reputable engine shop
should be able to look at the metal chips and give you a good guess
where they're coming from. But, again, with the age of your engine, any
further diagnostic work is really somewhat of an academic exercise.

Lead flakes sound like main bearings disintegrating. I don't know of any
other use for lead in an aircraft engine. Main bearings are soft, solid
bearings which use babbitt for bearing surfaces. Babbitt typically is a
combination of tin and lead, sometimes with a layer of silver underneath and
a hard shell of cast iron or steel. The hard steel crankshaft rotates
inside several sets of these bearings, typically one on each end and a third
in the middle. These bearings are said to be friction bearings (as opposed
to rolling bearings, like ball bearings); however, the few thousandths
clearance between the bearing surface and the crankshaft allow the crank to
hydroplane on a surface of oil.

Here's an article which will help you understand how these bearings work and
why you should be careful that they don't disintegrate:

http://www.eaa49.av.org/techart/mobil01.htm

"Les Sullivan" wrote in message
om...
I have a 1972 Cessna 172 with a Lycoming 0-320-E2D engine and it runs
[...]

" jls" wrote in message ...
Lead flakes sound like main bearings disintegrating. I don't know of any
other use for lead in an aircraft engine.

The main source of lead in aircraft oil is leaded fuel. However, that wont typically
show up as flakes.

When I had a similar experience with metal flakes in the filter we
sent the filter off to Lycoming to find out where the metal was
coming from. Answer: cam, lifters, and something on the pistons.
Went the Factory Reman route.



"Les Sullivan" wrote in message
om...
I have a 1972 Cessna 172 with a Lycoming 0-320-E2D engine and it runs
beautifully. It is on UK private category.
The engine is "original" and total time is about 2800 hours.
The engine had a thorough top overhaul quite a few years ago, maybe
around 1500 hours (new pistons etc) and has no problems with
compression, oil consumption, vibration or indeed anything at all. It
is well looked after.
Now the but.....
At its last annual (Christmas) some metal particles were found in the
oil filter.
--------------
The lab report says:
Filter section weight 397 milligrams
Major: - lead flakes measuring 0.1mm across
Minor: - blank
Traces: - Aluminium alloys - corroded fragments measuring up to 1.6 x
0.5mm
Iron - 0.5%
Nickel - 0.5%
Chromium steel such as sae8617,8620 or 8740 flakes measuring up to
0.9mm across
Iron - A low alloy carbon steel with no significant alloying
constituents such as sae 1010 slivers measuring up to 0.9 x 0.3mm
Miscellaneous - mainly fine particles.
--------------
I think it now means a complete overhaul to zero time.
The choice seems to be:
a) Factory Zero timed engine
b) Factory overhauled engine
c) Have my own engine worked on

What are your views about which way to go with this?

It is awfully tempting to keep the plane running and cut open the new
oil filter at, say, 20hours and see if there are any more particles.
As I said, compressions, oil pressure, power etc. are all good.

Maybe my greatest fear is that if I keep it flying, there may be
damage caused to the crankshaft or something which causes a big price
increase at overhaul due to the part being rejected.

Any advice / comments greatly appreciated.

Les

Howard Fenton retired last year. He gave his customer list to
Blackstone.

"Ron Natalie" wrote in message
. ..

" jls" wrote in message
...
Lead flakes sound like main bearings disintegrating. I don't know of
any
other use for lead in an aircraft engine.

The main source of lead in aircraft oil is leaded fuel. However, that
wont typically
show up as flakes.


OK, I'll play. Lead, a metal, and lead tetraethyl, a clear poisonous
liquid used in avgas to prevent combustion chamber knock, are two quite
different substances. Lead is an element, lead tetraethyl a compound.

"Ron Natalie" wrote:
The main source of lead in aircraft oil is leaded fuel.

jls wrote:
OK, I'll play. Lead, a metal, and lead tetraethyl, a clear poisonous
liquid used in avgas to prevent combustion chamber knock, are two quite
different substances. Lead is an element, lead tetraethyl a compound.

You're both right. There's no contradiction.

Remove SHIRT to reply directly.
Dave

Ron Rosenfeld wrote in message . ..
On 5 Feb 2004 04:26:18 -0800, (Les Sullivan)
wrote:

What are your views about which way to go with this?

For an opinion from someone with many years of experience in the business
and an excellent reputation (at least in the US), I would recommend you
contact Howard Fenton at:

SECOND OilPINION
7820 So. 70th East Ave.
Tulsa, OK 74133 (USA) 918/492-5844


I thought Howard retired last year. I seem to recall a big hubbub
in various forums about having to find a new place to get oil analysis
done.

John Galban=====N4BQ (PA28-180)