Engine corrosion

[Ebbie 2003]

Hello all

Looking for some opinions.

I took my airplane a PA28-181 to Florida for a major refurb in May of this year - a supposed eight week process.

Suffice to say not done to the agreed timescale.

I went to collect it in late September - looked great from 30ft away, up close not so much, the interior fit was appalling (I am going to put up a web page with the photos, some of it beggers belief) - so left there for the shop to resolve.

That is not the issue - I have been informed that the battery is flat "since your last visit" - this suggests that contrary to my expectstion that the engine has not been run gorthree months (the A&P does not respond to the question and I assume my supposition to therefore be correct - he refuses to tell me the Hobbs and Tach reading too - of course I can spend several thousand dollars going to look myself).

The question/query is this - is it likely that corrosion will have formed in the cylinders in this
time - the engine is a Lyc A4M - it has around 500 SMOH so not due for an overhaul just yet! There were no problems with the engine - indeed it completed a 20 hours series of IFR flights to get it to Florida.

So could problems have occurred - the airplane was not in a hangar?

If so anything that can be done to minimise the problems?

I ask as I may be fretting over nothing but as I have to fly this thing backover 2000 miles of open ocean the last thing I need is the engine having problems.

Thsnks

[9 lives]

The question/query is this - is it likely that corrosion will have formed in the cylinders in this time

I'm not quite sure what the "time" is, other than 3 months? The possibility of corrosion is to a large degree dependent upon what type of cylinders the engine has. If steel, then yes, corrosion is possible. If chrome, you're probably okay. Ground running an engine is not universally thought of as a good practice for preventing corrosion. Flying the plane regularly is. If you know that flying will not be possible, inhibiting is the best thing to do.

If the engine has suffered corrosion, there's not much you can do about it now (and there will be no way to quantify, or assign responsibility for that, so it is what it is). Just fly the plane regularly. Cylinder corrosion is not good, but in Lycomings, it's camshaft corrosion which will cause the really serious and costly damage to the engine. However, you have zero way of knowing the condition of the camshaft, until you remove cylinders, so no point fretting about it unless the engine starts making metal. If the engine starts making metal, remove it from service right away (certainly don't fly it across parts of oceans!).

Engines are consumable - wear and corrosion, to whatever degree of each. They are consumed while being used (wear), and while being parked (corrosion). Ground running does little to prevent the consumption. Inhibiting does a better job.

[Above The Clouds]

If a Lycoming is flown on average 3-5 hours per month but kept in a hangar what level of internal corrosion is to be expected ? The reason I ask is today I went to my aircraft and turned the prop through 30-40 times and I noticed some small drops of moisture dripping from the oil breather which kind of grabbed my attention.

[9 lives]

If a Lycoming is flown on average 3-5 hours per month but kept in a hangar what level of internal corrosion is to be expected ?

Not enough to register on the "concern" scale. The 3-5 hours a month is your winning way.

"Hangaring" a plane is not insurance against corrosion, unless that hangar is climate and humidity controlled, which is rare. Fly it once a week, change the oil regularly, and don't worry about it. Remind yourself that an engine is a consumable, and one day it'll have to be repaired/replaced. Budget for that, and enjoy flying it in the mean time....

[Ebbie 2003]

Thanks for the commentx.

The engine is a O360-A4M - not sure if we have chrome cylinders.

The three months - it seemd that nothing has been done over the past three months, normally prior to being entrusted to the shop it did fly 10-20 hours per month - my query was with airplanes sitting on the ground for three months.

When the guy revealed that it had not been run for the past three months and got my reaction he did not say he'd sprayed inhibitor, turned the prop regularly or anything else - so sitting in Florida, I am worried.I mentioned the not in a hangar simply to head off questions as to whether it was hangared amd whether it was climate controlled.

Seems I am going to have the cylinders borascoped and hope for the best - my concern is that I don't want to find that the engine eats itself 100 miles south on Antigua. Prior to this debacle I had flow the plane with confidence thousands of miles over open ocean, hundreds of miles from land with no viable SAR service - but this guy's general incompetence and poor service does not inspire confidence.

ps. The previous A&P died in mysterious circumsmtances following waking up in a hangar on Bequia with broken bones etc and no memory of what happened - turned out he had internal injuries to which led to his passing a couple of months later. Hence the need to fly it to the US for annual and its refurb.

[A and C]

I think you are getting a little too worried over the wrong things here, I would be surprized if your cylinders did not have a little corrosion in the upper cylinders but the is likely to be cleared by the first few sweeps of the piston rings in start up and have next to no detrimental effect.

If you are into oil analysis you will see a spike in the Fe but as long as this stabilizes at the second oil sample this is also OK.

The fact that the engine has not been turned is the only positive thing, turning the engine in storage just wipes the oil away that is protecting the surfaces.

I would be far more concerned about the cam shaft corrosion but as the engine has not turned this less likely to be a problem.

Chrome cylinders may seem to offer some corrosion protection ( the idea of using them was from the US navy in WW2 ) but chrome cylinders are not without their problems and these usualy outweigh the advantages especaly in aircraft that get used regularly.

Now all that remains is for me to wish you a Happy Christmas and raise a glass of Mount Gay 1703 to drink to your good health.......... and that of your engine !

[Ebbie 2003]

Thanks for the comments - makes me feel a lot more comfortable.

Happy Christmas and New Year to all.

[Steve6443]

A local club bought a 2004 P28A Archer 3 from the States, we did a thorough Pre-Buy, cut the filter - no metal. They then had it flown across last June. Due to issues with the Avidyne MFD, the aircraft had to be sent to a specialist avionics shop for repair, in total, the plane did around 8 hours flying in the past 6 months, of which 4 was in the past 4 weeks.

As the aircraft did approx 38 hours crossing, it was decided to do a 50 hour service and metal was found in the filter. On investigation, the hardened part of the cam was gone and it was wearing the followers as well - engine sent for rebuild.

So, if the plane has been sat around for a while and you haven't followed Lycoming's instructions for having engines not regularly run, start the plane, get the oil up to temperature and circulating then afterwards, cut the filter open. If the wear has already started, the trip across could be dangerous.... The cost of a filter against the risk of camshaft wear leading to low power on an SEP atlantic crossing is just not worth the risk.....

[A and C]

while cutting open filters is an important part of a maintenance program it is a relatively crude engine condition monitoring tool but oil spectro analysis will detect a cam shaft problem long before metal is found in the filter.

in the case outlined above the Fe level on the second oil analysis will not fall, in all probability the Fe level will rise rapidly.

before taking a single engine across a lot of water I would want to see the Fe level at the second oil analysis fall, if it did not do so the first thing I would do is pull a front cylinder and get a good look at the cam shaft, the front cams being the most likely suspects.

[piperboy84]

Who does oil analsys in the UK ? Anyone know a good vendor ?

[9 lives]

So, if the plane has been sat around for a while and you haven't followed Lycoming's instructions for having engines not regularly run, start the plane, get the oil up to temperature and circulating then afterwards, cut the filter open. If the wear has already started, the trip across could be dangerous.... The cost of a filter against the risk of camshaft wear leading to low power on an SEP Atlantic crossing is just not worth the risk.....

This is very wise advice, if you've "gotta know" your engine is okay. There are many factors affecting Lycoming camshaft disintegration, with corrosion being one. Unfortunately, when it begins, it cascades to bad quickly. I have flown Lycoming 360's which have not run for two years, ignored and frozen, to be inspected and be perfectly fine, and others, which are regularly operated coming undone. look for metal in the oil filter, if none, smile and fly....

[A and C]

It is my belief that the quality of Lycoming parts particuarly cams is not as good as it once was, probably because of pressure from the environmentalists as nitriding of parts has become very expensive. Add this to the need to keep costs competitive with the PMA providers and you have the recipe for prenuture component failure.

We have a 1960's vintage Lycoming O-320 that shows no signs of cam shaft failure at each oil analysis, yet far newer engines exhibit problems.

Piperboy84

I will send you the contact details for the oil analysis company we use when I get back into the office after the new year.

[horizon flyer]

The Lycoming with the cam over the top is a bad design for medium low usage engines as the oil drains off the cam and it rusts, best is running the cam in the sump so it stay sealed from the air and better lubricated.
i.e A Volkswagon beetle engine layout.

There are so many design faults in a Lyc360 it is a surprise it runs or gets a plane off the ground before it breaks and I have the bills to prove it.

The roller cam version is best, as no scuffing occurs on the cam bit more expensive but better option.