Engine Corrosion

RyanB

RyanB

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An interesting article from RAM Aircraft highlights a few points worthy of discussion.

They describe how the corrosion and oxidation process begins after just 7 days without use. If this is so, wouldn’t a large majority of general aviation aircraft with piston engines have internal corrosion? Especially those who live in climates that prevent frequent flying.

What says y’all?

http://www.ramaircraft.com/Maintenance-Tips/Engine Corrosion 02-15.pdf
 
yup....take a look at this 2004 OH. It looks pretty bad....I think it sat for years without any use too.
 

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We know it happens.
The big question is, Is it a metallurgical deficiency that these parts corrode and fail, beginning with only a brief time of non-use? Or is it like the manufacturers are trying to convince us, it’s our fault for not flying our planes like a freight hauler or flight school, and we are expecting too much of the metal?
 
Ryanb said:
An interesting article from RAM Aircraft highlights a few points worthy of discussion.

They describe how the corrosion and oxidation process begins after just 7 days without use. If this is so, wouldn’t a large majority of general aviation aircraft with piston engines have internal corrosion? Especially those who live in climates that prevent frequent flying.

What says y’all?

http://www.ramaircraft.com/Maintenance-Tips/Engine Corrosion 02-15.pdf
Click to expand...

Looks like they had an open crankcase with no oil or protective spray on any of the components to demonstrate what happens to wholly unprotected steel surfaces. Sure it'll start rusting out in the open, lol. However, if it was a closed crankcase with oil that had been circulated, I doubt you'd see any signs of rust beginning to appear. Rotating the prop every week isn't likely to circulate enough oil to be meaningful.
 
Guess it’s time to buy a RAM conversion lol
 
I like to fly inside of 14 days, at least 30 minutes. I use Canguard, think flying routinely is more helpful though.
 
Yea that is an absolute worst case which is not really what happens. The cylinders are the first thing to go unless you have chrome ones in which case they will be fine. Obviously the cam will be next especially on a Lycoming. There really isn't a threshold. Run it till it makes metal and continues to get worse. At that point you are on borrowed time. Once you eat through the hardened layer it will accelerate rapidly.
 
So the solution is to get a Ram conversion and fly more often.
 
The problem is, even if you try to do everything right per all the guidance published, corrosion still happens and there is little people can do about it. Some engines simply seem to rust and others don’t. I've had a lot of these engines apart and I feel that the engine installation/application has more influence on the outcome than anything else, assuming that the airplane gets flown at least once in a while.

A few months ago I tore down an engine that had 900 hours since an overhaul that was done in the late ‘80s. Most of those hours were flown back in the early and mid ‘90s, as in more recent years the airplane mainly sat in a museum. It looked great inside and could have went back together with minimal work.

This past week I had a similar engine that was built in 2016 apart and had 400 hours of consistent flying on it. There was minor rust everywhere in that one.

My point? The engine that was "abused" by inactivity and no preservation was in better shape than the one that someone did everything "right" on. So my advice is to do what you can and accept that there is risk you can't mitigate. I'm curious to see what the future holds if/when we see alternative fuel become more mainstream.
 
mondtster said:
This past week I had a similar engine that was built in 2016 apart and had 400 hours of consistent flying on it. There was minor rust everywhere in that one.
Click to expand...

Some are saying that there has been changes in the metallurgy and new engines are rust buckets compared to those made 25 years ago. "Keep your old parts when overhauling. Avoid buying new." (Beechtalk is full of this sort of info)
 
Let'sgoflying! said:
Some are saying that there has been changes in the metallurgy and new engines are rust buckets compared to those made 25 years ago. "Keep your old parts when overhauling. Avoid buying new." (Beechtalk is full of this sort of info)
Click to expand...

Ive had that theory as well, but from what I’ve seen it doesn’t consistently hold true.
 
I hope the economy holds together because my plan is it overhaul the 53 year old O320 this winter, like after the elections. I'm planning on doing all the disassembly/reassembly myself so lotta picture opportunity. I've been slowly collecting new stuff for it.
 
bnt83 said:
I hope the economy holds together because my plan is it overhaul the 53 year old O320 this winter, like after the elections. I'm planning on doing all the disassembly/reassembly myself so lotta picture opportunity. I've been slowly collecting new stuff for it.
Click to expand...
Oh wow, how many hours on it?
 
The 414 flew 100 hours between 2000 and 2016 when we bought it. It'd sat for 6 years not running at all.

Of all the problems it had, engine corrosion was not one of them.

Corrosion can be an issue on engines. But almost 100% of the piston fleet would be worthless if 7 days of sitting was really a problem.
 
Same old advice: Don't go out and pull the airplane out of the hangar and run it for ten minutes and put it away. Most crankcase moisture comes from just that. Fly it hard or leave it alone.
 
Dan Thomas said:
Same old advice: Don't go out and pull the airplane out of the hangar and run it for ten minutes and put it away. Most crankcase moisture comes from just that. Fly it hard or leave it alone.
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Yeah, when we bought our Skyhawk, it had low hours, but the owner had lost his medical, and for several years he did an annual and ran it up and changed the oil (he was a corporate ATP, and had A&P with IA) and put it back in the hangar. The oil pan was essentially eaten through at the bottom from the moisture. We had it rebuilt (with an overbore due to pitting), and then again a few hundred hours later, when I tested a runway with a propeller.
 
I am in Arizona. My plane can sit for months without corrosion. I have had airport cars sit up to two years and no cam corrosion. I bet the camshaft material is the same. So much undocumented BS out there.
 
The pics from the ad look worse than my truck’s brake rotors after a long time sitting. And I live within 300’ of the Pacific Ocean.

It’s a shame they can get away with falsifying the situation so much.
 
I frankly don't see the corrosion in those two pictures. There may be pits on the lobes of the cam but I don't see that either. Otherwise the area between the lobes is a copper plating that is used in the manufacturing process after rough machining to block subsequent carburizing heat treatment. It is ground off the lobes after heat treat and quench to get the final cam profile.
 
nrpetersen said:
I frankly don't see the corrosion in those two pictures. There may be pits on the lobes of the cam but I don't see that either. Otherwise the area between the lobes is a copper plating that is used in the manufacturing process after rough machining to block subsequent carburizing heat treatment. It is ground off the lobes after heat treat and quench to get the final cam profile.
Click to expand...

Post #17 - he said it was a joke. There isn't corrosion there.

To find the nasty corrosion, look at the advert in the OP's first post. The company posts photos of engines that look like junkyard scrap, and falsely claim it's from seven days of sitting.

I guess their target market are people that have never seen the real insides of an engine before.
 
Rgbeard said:
Post #17 - he said it was a joke. There isn't corrosion there.

To find the nasty corrosion, look at the advert in the OP's first post. The company posts photos of engines that look like junkyard scrap, and falsely claim it's from seven days of sitting.

I guess their target market are people that have never seen the real insides of an engine before.
Click to expand...

Rgbeard said:
The pics from the ad look worse than my truck’s brake rotors after a long time sitting. And I live within 300’ of the Pacific Ocean.

It’s a shame they can get away with falsifying the situation so much.
Click to expand...

They didn't falsely claim anything. In the text they specified that it was sprayed with a salt water solution to simulate harsher coastal atmospheric conditions. It's not false, but perhaps a good bit misleading since those internal components don't normally get exposed to the concentration of salt water that was used in their "experiment".
 
I didn't say "falsely claim" -- I said "falsifying the situation".

Which is akin to spraying metal internals with saltwater, claiming it simulates being near the coast.
 
so how real is that?....when would the inside of the engine ever see salt air? There is no flow thru the breather.....it normalizes the pressure....there is no flow.
 
Checkout_my_Six said:
so how real is that?....when would the inside of the engine ever see salt air? There is no flow thru the breather.....it normalizes the pressure....there is no flow.
Click to expand...
There is flow past the rings when the engine is running - intake air plus fuel / exhaust. So there will be a little (little) salt coming in - but not much when compared with all the stuff in the blowby. Main flow with the engine running is out the breather. When the engine is off, you will get some flow in/out with the diurnal temperature changes and the air inside the engine expanding / contracting.
But nothing like getting sprayed with salt water and not having any oil all over it.
 
very little....compared with that spray test. o_O

I use to do salt spray testing.....it isn't a very repeatable or realistic test. More for side-by-side comparison testing.
 
Capt. Geoffrey Thorpe said:
There is flow past the rings when the engine is running - intake air plus fuel / exhaust. So there will be a little (little) salt coming in - but not much when compared with all the stuff in the blowby. Main flow with the engine running is out the breather. When the engine is off, you will get some flow in/out with the diurnal temperature changes and the air inside the engine expanding / contracting.
But nothing like getting sprayed with salt water and not having any oil all over it.
Click to expand...

A couple of years ago we had a long discussion here about the diurnal temp changes, the volume of a fuel tank and the volume of a crankcase, and the amount of water in a cubic foot of saturated air. Taking temperature extremes and assuming saturated air, it takes a long time, many temp cycles, to accumulate any moisture of note, and that's assuming that ALL the water stays in the tank or case and only dry air escapes, which is obviously untrue.

Any one who has ever pulled a cylinder off a crankcase and looks inside can see how little volume is in there once the crank and con rods are in it. And anyone who removes a cylinder after an engine has been ground run (as in right before an inspection) knows that you'll find water in the rocker cover and sometimes between the piston and cylinder. That water wasn't from the environment.
 
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