Lycoming O-360-A1D

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May 7, 2020
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PA
Thoughts on this analysis? Mooney M20c. Engine has about 500 hours and the cylinders are not chrome. Probably need to establish a trend since this is the first analysis since I have had the aircraft.
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I think Chrome would come from the face of the rings or the rocker arm shafts on that engine?

That is a good stout and efficient airplane.
 
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4678473/Aircraft_UOA_fact

That link is to one of my threads talking about UOA results and aircraft engines. I believe it's worth a look, although it does not address your questions.

It is correct to start a trend, as that is the way the tool is useful. Please don't think the results indicate engine wear rates. A UOA result with lower "wear metals" may have no bearing on wear rates per hour.

Bottom line: The UOA, (soap check) or what ever your shop is calling it, is just a tool. A tool that is very easy to misinterpret, a tool that can drive unnecessary work and can even result in a panicked aircraft owner! Always remember to cut your oil filter apart and carefully inspect the filter element. If you find a teaspoon of debris, you have a problem. If you have nothing more than a few small flakes, things are probably normal.


Also note: You can have higher than normal "Cr" and not have any problems what so ever (very likely) . Disassemble the engine and never find anything wrong or even the source of the Cr. You can also have low Cr and be experiencing a worn out chrome plated part. You can also have higher than normal "Cr" and have a wearing part. The long term trend is what alerts a sharp owner to an impending problem. And even then, the accuracy rate is just this side of poor.
 
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I'd like to add in a story about our EC-135 helicopter. An oil sample showed higher than normal moisture. The manual requires removal of the (rather large and robust) pinion gears (2 of them) for corrosion inspection if a certain threshold is exceeded. Of course, the tech found 2 tiny chips, one on each gear, that he could feel with a ultra sharp pick. They were hard to see, and even harder to feel. But he rejected the gears, despite the fact that the flaws could never have caused a problem. Mind you, I had been changing the transmission oil every 30 hours, in an attempt at preventing corrosion and wear.

The replacement pinion gears can't be used with the older ring gear we had (of course) so a replacement ring gear was required. Upon disassembly, there were a few "mandatory" service bulletins that were due upon overhaul (remember they really are not mandatory, but the overhauler has a policy of not giving the unit back until those are completed) (yes the replacement of more gears) and in the end, it took American Eurocopter(now Airbus) and ZF (the transmission gear maker) just over 9 months and $800,000 to fix a "non problem".

It's good that we have all new gears in our 1000 hour transmission. But we are now experiencing "chip" lights on a regular basis....
 
Originally Posted by Cujet
The replacement pinion gears can't be used with the older ring gear we had (of course) so a replacement ring gear was required. Upon disassembly, there were a few "mandatory" service bulletins that were due upon overhaul (remember they really are not mandatory, but the overhauler has a policy of not giving the unit back until those are completed) (yes the replacement of more gears) and in the end, it took American Eurocopter(now Airbus) and ZF (the transmission gear maker) just over 9 months and $800,000 to fix a "non problem".

It's good that we have all new gears in our 1000 hour transmission. But we are now experiencing "chip" lights on a regular basis....

For a guy who drives a Camry my mind is blown at what a copter costs to keep going.
crazy2.gif
I get it, it goes with the territory: at work we'll spend up to a million to buy equipment to make things that cost a buck or whatever, but it always boggles my mind.
 
Thanks everyone, I figured while the chrome number is a little bit high, I shouldn't read much into it. I think the value of the analysis is noticing changes long term. I did cut the filter and it looked fine.
 
Not knowing how long the oil has been in use (calendar, not engine time), and storage conditions during storage, it could be you got a little rust accumulation on the cylinder walls. Lycoming recommends long term storage preparation for periods exceeding 30days.
Chromium comes from the rings in a steel cylinder. The iron will be from the camshaft and cylinder walls.

Most of the numbers look really good for a 2431hr smoh.
You really should consider switching to AeroShell W100+, or Victory 20w50 to protect the camshaft. Lycomings require the additives per AD.

More aggressive leaning will lower the lead levels. Most manual recommendations date to original approved fuels of either 80octane or 92/96. MUCH less lead than 100LL. Leaning to peak power won't hurt the engine as long as safe oil temps and cylinder head temps are maintained.
 
Originally Posted by GooseGestapo
Leaning to peak power won't hurt the engine as long as safe oil temps and cylinder head temps are maintained.


That's likely quite true in cruise flight at altitude. However, on some Lycoming engines, leaning to peak power, under certain conditions, will bring on detonation. One example where a problem can crop up would be flying low, at full throttle, zooming over the Long Island Sound coastline in late fall, with the crisp, cold air that is common in early December. Cylinder pressures can reach the point where detonation is a certainty, unless the excess fuel of the full-rich mixture knob position is used to keep pressures down.

We'd all like to think detonation can't happen with 100 octane fuel and relatively low compression engines. However, it can happen if an engine is operated improperly. One way to operate improperly is to run at a peak power mixture at the "wrong" time.

The reason I bring that up is that I know somebody who did just that and experienced massive detonation and subsequent engine problems.
 
I've always wondered what the reason is that avio ICEs dont use modern "low saps" oils from a avtomotive industry?

Since the main reason for use of avio "ashless" oils is that they dont faul sparkplugs....
 
Originally Posted by Cujet
The replacement pinion gears can't be used with the older ring gear we had (of course) so a replacement ring gear was required. Upon disassembly, there were a few "mandatory" service bulletins that were due upon overhaul (remember they really are not mandatory, but the overhauler has a policy of not giving the unit back until those are completed) (yes the replacement of more gears) and in the end, it took American Eurocopter(now Airbus) and ZF (the transmission gear maker) just over 9 months and $800,000 to fix a "non problem".

It's good that we have all new gears in our 1000 hour transmission. But we are now experiencing "chip" lights on a regular basis....

For a guy who drives a Camry my mind is blown at what a copter costs to keep going.
crazy2.gif
I get it, it goes with the territory: at work we'll spend up to a million to buy equipment to make things that cost a buck or whatever, but it always boggles my mind.
We need to remember Aircraft is a Latin word ,,, which means very, very expensive.
 
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