testing oil samples

[rhtrudder]

Was helping a mechanic mate collect oil samples out of a articulated dump truck recently which were sent onto Caterpillar for analysis, wondering whether it would be prudent to do the same with my 914 ,which now has over 1300hrs, even though it has no mechanical issues.

 

 

[dazza 38]

It wouldnt hurt, the RAAF do oil samples on their engines.

 

 

[Downunder]

I recon if the mag plug and oil filter inspection look good, I wouldn't bother with the oil itself....

 

What about taking the sample but only sending it away if the first two are suspect?

 

I think it would be more beneficial (money wise) spending the extra on more frequent oil/filter changes and general maintenance/inspections ie carb overhauls. Especially if using avgas.

 

 

[skeptic36]

I asked the mechanics to get one done on my tractor when it kept blocking hydraulic filters. No, no nothing wrong with the tractor they say, must be your implements, I say, other tractor uses same implements and it's ok.

 

$17000.00 later the tractor has a new brake disc and all the bits of the old one cleaned out of it.

 

They either lied about having the oil sample tested, or oil sampling is useless

 

 

[jetjr]

Oil analysis works on watchng changes and trends so a one off test doesnt often say much

 

 

[facthunter]

It's generally used by fleets trying to run Long life oils (Extended Drain. Special additives which get depleted, not higher quality oil) to higher mileages and checking on how they are standing up. It's not relevant to our type of operation where the drain periods are well short of what is possible from a normal oil. Use a magnetic plug somewhere and cut your filters open and examine them is all you need to do. A magnet will only pick up ferrous material but that's particularly important where a reduction gearbox is used. The test would also pick up excess blowby products and be an indicator to some extent but your compression test is more effective. Nev

 

 

[dazza 38]

It wouldnt hurt, the RAAF do oil samples on their engines.

I better be more specific, the F111's Pratt and Whitney TF30 engines had regular soap samples.

 

 

[facthunter]

Synthetic plus water or whatever you guys wash then out with. Nev

 

 

[dazza 38]

I better be more specific, the F111's Pratt and Whitney TF30 engines had regular soap samples.

Soap stands for Spectrometric Oil Analysis Program

 

 

[facthunter]

I wonder why I didn't know that already. I thought it made your skin wrinkle..Nev

 

 

[dazza 38]

I wonder why I didn't know that already. I thought it made your skin wrinkle..Nev

Sorry about that Nev, I should have been more specific.

 

 

[facthunter]

You do get stuff that looks like soap when the motor runs too cold.. You don't have anything to apologise for dazza .Thanks anyhow. Nev

 

 

[Vev]

Correct Nev .... the white stuff is water reacting with the zinc anti-wear additive in the oil.

 

There is very easy field test you can do to test for water contamination, which will measure down to about 0.5%.... take a representative sample of oil (after running and hot) and put a drop (use an eye dropper) of this into the middle of a small aluminium tray (the same as you use for cooking a small tart) and put a lighter under it and heat. If it spits it has some absorbed water, if it doesn't it's free of water.

 

Cheers

 

Vev

 

 

[Yenn]

Oil analysis is regularly used in GA aviation, especially in the USA. It is a guide to engine condition when used at every oil change. If for example your iron content goes up and at next change it is higher again, the probable diagnosis is cam or cam follower wear and breakdown. Aluminium, copper and other things can point to different problems in different engines.

 

With recordable CHT and EGT instrumentation we now have an even better diagnotic tool. Use the two together for real peace of mind.

 

 

[Mriya]

As a maintainer I recommend them, but as highlighted already they provide most benefit in allowing identification of trends over the longer term. If an engine is running 'on condition' I will automatically do SOAP test. Some older aircraft only have oil strainers, so with no cartridge filter to cut open, regular oil analysis is another tool to monitor the health of your engine.

 

Not a bad record to be able to show to a prospective buyer when the time comes to sell. They will have extra confidence that the engine internals are healthy if you can show them these results.

 

The cost is 'chicken-feed' compared with the investment in your engine. Well worth the investment IMHO.

 

 

[cscotthendry]

Was helping a mechanic mate collect oil samples out of a articulated dump truck recently which were sent onto Caterpillar for analysis, wondering whether it would be prudent to do the same with my 914 ,which now has over 1300hrs, even though it has no mechanical issues.

I do what Rotax recommend, no more, no less. Rotax have thousands of engines in the wild and they get feedback about the running and maintenance of them which they pay attention to. I believe that if oil analyses were useful for Rotax engines, Rotax would say to "get 'em done".

 

 

[facthunter]

I don't believe it's cost effective, provided all the other things are done. Do it if you feel it's worthwhile. Some engines I've flown behind were never oil changed, because the oil consumption was enough to keep the oil showing ok when tested, but WE change oil at about 1/4 of it's safe life in most of our engines. Oil is relatively cheap and so it doesn't matter much as the amounts are quite small. If the full flow filter is fine that helps provided it doesn't clog and bypass. In dusty conditions keep the hours between changes short. Open your filter and check with a magnet and examine any flecks of metal with a magnifying glass. Nev

 

 

[Vev]

A simple process to undertake a wear metal and particulate examination of your filter content.

 

http://www.eaavideo.org/video.aspx?v=3735936001

 

Cheers

 

Vev

 

 

[facthunter]

Inadvertently there was shown a situation where the old neoprene washer stayed with the engine. Had that not been detected the oil pressure would have forced the extra washer out and the engine would have lost the oil very quickly and failed in no time flat. One washer is backed up by a rolled steel edge but it isn't big enough to locate two. Nev

 

 

[Mriya]

I do what Rotax recommend, no more, no less. Rotax have thousands of engines in the wild and they get feedback about the running and maintenance of them which they pay attention to. I believe that if oil analyses were useful for Rotax engines, Rotax would say to "get 'em done".

I have no problems with your policy here. SOAP's are an extra diagnostic check and if not required as part of a manufacturers schedule, I see them as an optional extra, however as mentioned, once an engine is 'on condition' you have by default moved outside of the manufacturers recommended schedule (at least for the engines we are talking about here). I therefore see SOAP checks as a wise precaution to help detect trends in an engine that is now operating beyond the manufacturers schedule.

 

 

[Pearo]

I know a bloke who owns an oil testing business. I dont know anything about it, but if you want me to direct specific questions to him let me know. Might even be able to convince him to become a member here.

 

 

[old man emu]

I thought oil testing would be expensive, but when I Googled it, I found this Australian mob, www.e-monitor.com.au , which provides a sampling kit for collection and return as well as analysis and report for $35.20. That's the price of about four litres of oil.

 

The question is: how often would you do the testing to determine an adverse trend? Most would only consider doing this test at every annual, or 100 hourly as they came up. Would this be too late to prevent major damage?

 

From the above web site:

 

" e-Monitor is a low cost predictive maintenance service that detects problem causing contaminants and out-of-line wear rates in engines, transmissions, rear-ends, hydraulic systems, and other oil lubricated mechanisms. The purpose of e-monitor is to provide a reliable method of monitoring the trend of wear on moving parts within vehicles. This allows you to spot small changes from the normal wear patterns enabling you to avoid progressive damage induced failures."

 

I can see that this procedure would be very useful in high usage vehicles such as commercial ground vehicles, but I wonder if, apart from being of intellectual interest, it is of any more benefit in a recreational aircraft than the use of a magnet in the oil drain plug and cutting the oil filter open to inspect the filter paper.

 

OME

 

 

[Oscar]

That's a better price than the Hastings-Deerings mob I used for my Jab. initial run tests ( about $100 for a pair of tests: after first hour and after 5 hours, as selected by me..)

 

 

[facthunter]

With your testing kit you probably get what you pay for. None of this will detect a crack or a bolt or a piston skirt ready to break or a carbonned ring groove A useful thing would be something measuring blow by rate, but where does one stop in all of this? Make sure your engine is installed correctly. That it is baffled/directed so the air gets where at should at the rate it should from the the beginning of it's life and feel the compression before every flight. Get someone with a good engine to show you what it feels like. Use appropriate caution especially with a conventional motor with magneto's. They were always run out of fuel by shutting it off during taxiing and check both switches off, kill the engine, at some stage too. The check has you turning the motor slowly but an impulse magneto sparks just as good slow, as fast. If your engine vibrates, runs rough, or has lower power than normal investigate it straight away because engines don't usually fix them selves. It's "been like that for days " doesn't cut it with an aeroplane engine. Nev

 

 

[Vev]

Oil and wear debris analysis are powerful tools in the right hands, particularly on some equipment where it may not have a spanner put on it for hundreds of hours. It will provide some insight if things are going wrong before something breaks and allow you to undertake corrective action or take it off line in a timely manner too repair.

 

However in the context of the type engines and flying we do, I think it's an over kill and almost behind the curve as we change our oil at 25 or 50 hour intervals and should also be changing our oil filters too.

 

The oil filter will give a reasonable view of wear metals, both ferrous and non-ferrous, along with combustion and foreign ingress materials ... to keep a trend of this simply photograph the residual materials. If you see an increase in debris you then need to start looking harder.

 

As Nev said earlier, do proper pre-flight checks ... I personally believe in doing a pull though before every flight ... if you get a soft blade, find out why!

 

Cheers

 

Vev