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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 |
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#3
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#4
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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 [...] |
#5
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" 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. |
#6
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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 |
#7
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Howard Fenton retired last year. He gave his customer list to
Blackstone. |
#8
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"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. |
#9
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"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 |
#10
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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) |
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