Moving to PPI on an aircraft that has not flown since June of 2015. PPI focus will be to determine if there's any corrosion inside the engine. We will do an Oil Analysis, and we will be pulling a cylinder to see the lobes etc.
Question: Are we better to have the engine run-up flown for say 90 min before the Oil Analysis? Or is it more advisable to have the AME pull the cylinder first before the engine is started?
I'm afraid that if we start the engine and run / fly it then the debris may burn off and not be found. Whereas if we pull the cylinder we may have a better chance to answer the corrosion question. We plan to do both procedures anyway. I'm just wondering which should be done first??
0-320, no fly 4 6mo. Best procedure to identify corrosion?
Moderators: sky's the limit, sepia, Sulako, North Shore
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
WOW!!! 
Is it sitting out in the rain with no plugs in it???
People panic a lot for things like this but honestly 6 months parked, especially if it has single weight oil isn't that bad... I doubt anything would have happened, unless they were ground only running the engine for the six months! I'd be more worried about how well the engine was maintained before... how much did it fly? Regularly? Oil consumption? Work done? Type of flying (short hauls, long ones?)?
Engine oil should be changed warm so it flows nice. Drain a bit of oil and then take your sample mid stream so it catches whatever is suspended but the readings might be off if a bit if some minor rust has formed, on the cylinder walls for instance. I wouldn't bother with the oil analysis at this point. Do it at the next oil change, then start doing it regularly. Pulling the cylinder for six months of non-use??? Seems overkill to me, more of a chance of screwing something up doing that. HIGHLY doubt any cam damage at six months, unless it's a really high time engine that has other factors against it...
Oil analysis is mostly for progress report over time, it won't tell you much in one shot. The filter (or screen) will tell you more about the here and now of what's going on...
Is it sitting out in the rain with no plugs in it??? People panic a lot for things like this but honestly 6 months parked, especially if it has single weight oil isn't that bad... I doubt anything would have happened, unless they were ground only running the engine for the six months! I'd be more worried about how well the engine was maintained before... how much did it fly? Regularly? Oil consumption? Work done? Type of flying (short hauls, long ones?)?
Engine oil should be changed warm so it flows nice. Drain a bit of oil and then take your sample mid stream so it catches whatever is suspended but the readings might be off if a bit if some minor rust has formed, on the cylinder walls for instance. I wouldn't bother with the oil analysis at this point. Do it at the next oil change, then start doing it regularly. Pulling the cylinder for six months of non-use??? Seems overkill to me, more of a chance of screwing something up doing that. HIGHLY doubt any cam damage at six months, unless it's a really high time engine that has other factors against it...
Oil analysis is mostly for progress report over time, it won't tell you much in one shot. The filter (or screen) will tell you more about the here and now of what's going on...
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
This engine has 1400hrs TBO, It flies about 15 hours year. As mentioned earlier its been sitting for 6 months (east coast). We are considering buying. During the PPI we would like to make sure we have a proper test for corrosion. AME suggested pulling a couple cylinders. We are unsure if we should run the engine for a couple hours and do the oil analysis, or if we should do the cam inspection prior to starting the engine.
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
Hmmm that would change things... 15 hours a year... just over an hour a month... not much. Was it always just put away all the time with no preservation?
I'd pull a jug, especially if it's a Lycoming, you'll need to anyways to see the cam. I wouldn't bother with an oil inspection at this stage, you can do it if you want but in this case do it before you run it because if there is rust inside it will contaminate the readings. Won't tell you much anyways, especially if it's been sitting so much, it will give you too many false readings.
Pull the filter/screen for sure and check it for metal. I'd really account for the lack of use in negotiations and assume the worst, that's a lot of sitting for an engine! They can be a really good deal though in some cases!
I'd pull a jug, especially if it's a Lycoming, you'll need to anyways to see the cam. I wouldn't bother with an oil inspection at this stage, you can do it if you want but in this case do it before you run it because if there is rust inside it will contaminate the readings. Won't tell you much anyways, especially if it's been sitting so much, it will give you too many false readings.
Pull the filter/screen for sure and check it for metal. I'd really account for the lack of use in negotiations and assume the worst, that's a lot of sitting for an engine! They can be a really good deal though in some cases!
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
Do 2 samples. Take a sample, pull all the plugs, pull 2 jugs(one back and one front), scope the other 2, pull something to look at accessory drive. Assemble, run, sample oil, check filter/screen. Buy.
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
Thanks for the advice, We did negotiate price. i should have added, it had it annual with fresh oil change, and has sat for 6 months. Thetas why we thought maybe running it for a couple hours and then doing a oil analysis, if rust contaminated the readings, I think that would be enough to realize the health of the engine is failing. correct?
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
Quick check is to pop off the rocker covers. The springs can get quite rusty quickly.
But look before running.
But look before running.
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mikevictorpapa
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Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
What order does the AME suggest doing it in?
If you are concerned there may be corrosion, definitely inspect the cam and lifters. Paying for a pre-purchase inspection is intended to save you a lot of money down the road. Personally, I think pulling the jugs before running the engine makes more sense. Have the filter cut open and inspected as well.
As for oil analysis, I like the idea of 2 samples. One taken prior to running it, and then a second is taking after running the engine. It is unlikely the second sample will show much different from the first sample, but it can't hurt.
If the motor comes out clean after all is said and done, you might kick yourself for spending the extra money. But it is definitely worth it, as now you know for a fact what exact state the motor is in. You'll have it signed in the logbooks that no corrosion was found, which is a nice to have for others to see when you go to sell the plane.
I had the same dilemma when buying my plane. Most AME's figured there wouldn't corrosion, but we didn't know that for a fact. $600 later and I know for a fact there is no corrosion. Have put 80 hours on the plane since without a worry.
If you are concerned there may be corrosion, definitely inspect the cam and lifters. Paying for a pre-purchase inspection is intended to save you a lot of money down the road. Personally, I think pulling the jugs before running the engine makes more sense. Have the filter cut open and inspected as well.
As for oil analysis, I like the idea of 2 samples. One taken prior to running it, and then a second is taking after running the engine. It is unlikely the second sample will show much different from the first sample, but it can't hurt.
If the motor comes out clean after all is said and done, you might kick yourself for spending the extra money. But it is definitely worth it, as now you know for a fact what exact state the motor is in. You'll have it signed in the logbooks that no corrosion was found, which is a nice to have for others to see when you go to sell the plane.
I had the same dilemma when buying my plane. Most AME's figured there wouldn't corrosion, but we didn't know that for a fact. $600 later and I know for a fact there is no corrosion. Have put 80 hours on the plane since without a worry.
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
Problem with light corrosion is thay the effects wont turn up for a few hundred hours. The Nitride hardened steel surfaces are very very thin so light rust will take the hardened layer and the steel is then softer and wears much faster. Few hundred hours instead of a few thousand to destroy the cam or lifters. Im not sure what rust looks like in an oil analysis. They check for iron buy not oxygen so a light rust likely would not spike the iron content appreciably I guess.
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wrenchturnin
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Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
If it were me, 6 month's is nothing. GA aircraft routinely sit for 6 monthes. Check the oil. Start it up. Fly it. Drop the oil and check for metal in the oil filter. If all good, away you go. Forums are full of exaggeration and worse case senario awnsers. Best way is to read everyones opinion and form your own that your comfortable with. Also remember to be listening to your AME if he's experienced and legit. He's got the license and ultimatly its up to him.
Good Luck.
Good Luck.
Re: 0-320, no fly 4 6mo. Best procedure to identify corrosio
http://www.lycoming.com/Portals/0/techp ... rcraft.pdf
Lycomings advce on the subject. Pretty much agrees with all the posts here except the last best case scenario.
Lycomings advce on the subject. Pretty much agrees with all the posts here except the last best case scenario.
