The consequences of not running the engine for 7 months (corrosion)
7 months ago I decided to bite the bullet and save time by paying someone to do some work on my aircraft.
The work that should have taken a month at max has so far taken 7 months, not because it’s difficult but because the bloke I employed thinks that it is Ok to take on 100 jobs at a time and just pick and choose what he feels like doing when he feels like doing it.
Since the completion of the work was always “imminent” I never bothered much to worry about the engine being unused in a heated hangar but after the elapsed time I thought it best to pop the rocker covers off and take a peek.
this is what I found:
Ouch! Corrosion? And that is only the visible part.
I’m not making a statement either way, but I wouldn’t dismiss the possibility of corrosion being formed over time by water vapor as the engine was run and shut down, perhaps with low oil temperature, as opposed to being caused by 7 months of inactivity. That assumes the material visible on the valve spring is rust.
I’ve seen similar before on engines that are run regularly for short periods or with excess cooling. More often than issues caused by a few months of total inactivity.
I can see from your post that your unhappy with this guys work, though this is not caused by 7 months in a heated hangar. It wouldn’t be fair IMHO to blame him for this.
In the absence of oil analysis, it won’t be possible to prove when the rust happened.
If the engine has not been run for the 7 months and has still not been run yet, you could get a general idea by taking the plugs out and – without moving the crankshaft – looking in the bores with an endoscope. If there is rust in some of the bores above the travel of the top ring, that obviously happened since the engine last ran.
It won’t help you sorting this out, however.
AFAIK a corroded engine is not airworthy, though that actually matters only on a certified aircraft, and it matters only if you know about it 
I would not fly with it. Surface corrosion on springs (or any highly stressed part) makes them susceptible to failure.
But different people have different attitudes to risk. In a one-time “my” hangar, years ago, there was one of these. It sat there for years. Every 6 months, the owner turned up in a Porsche, sunglasses, leather jacket, the lot, and took it out for a thrash. It took a while to start and there was a big cloud of black and red (rusty) smoke, but it flew ok. Mind you, there was also a 421C which flew only a few hours a year, between 20k Annuals, and that was the same (only the hangarage on that cost a bit more than the heli). I also know of an AOC operation which flies a piston plane which was found abandoned for many years, painted up, engine never opened (well the oil filter gets checked) and it’s been flying fine for some years 
As Clint Eastwood would say, do you feel lucky?
I’d be inclined to replace rusty valve springs as and when the opportunity arises, or at least to check periodically for this:
I would like to know if CAMGUARD could have prevented this.
I heard that there is a product other than camguard that releases an anti-corrosion vapour. Anyone know about that?
I will take these valves out and assess the damage and replace if necessary.
Silvaire is right in that the last flight was a very short one; ideal conditions for condensation to develop.
The one thing I have done periodically is turn the prop but nonetheless I will examine the bores with a scope and see what’s what. The engine has only done 35 hrs.
Stickandrudderman wrote:
The engine has only done 35 hrs.
Over what period? Since new? or OH?
Since o/haul two years ago.
