Grounded for a year. Precautions?
 

Perhaps I am getting too cautious in my old age.
The ATL has been grounded by EASA paperwork for over a year. But now all that is sorted and I am ready to aviate again. The engine has been checked over, taxi runs made, new oil and spark plugs, etc. Used regularly over the last ten years the Limbach has been so reliable that I have hardly given a thought to engine failure. But now after languishing in an unheated hangar with cold and damp weather it has become an unknown quantity.
On the first couple of flights since being grounded both engine and pilot are potentialy dangerous for each other.
Plan A is to wait for a stiff wind straight down the longest of our two runways (03/21) and climb at max rate to achieve 500 ft or more within the airfield boundary. A failure before 500 ft - land ahead. Above 500 ft turn to land on the crosswind runway(27/09)? Or not!
Any opinions on how I should (or should not) conduct these first post grounded flights would be welcome. :sad:

Can you borescope check for camshaft corrosion? On most engines you have to pull a cylinder to see the camshaft, I think.

A borescope of the cylinders would be a must after a 12m non-use.

I'd just do some ground runs, and once happy go for it with it in mind that the engine might fail and have a plan to deal with it ;) I don't think a bit of surface corrosion can be that deadly or else half of the aeroplanes in the UK would be dropping out of the sky due to non use!

If you do decide to fly, keep a close eye on oil consumption and consider an early oil change (after 5 hours or so) plus oil analysis. At the same time you might want to do compression testing of the cylinders.

And what about your personal currency? Are you current enough to deal with EFATO and other things the aircraft might throw at you? Maybe it's a good idea to do an intensive workout, practicing things like that, in an aircraft that has the same flying characteristics of the ATL, but hasn't been grounded for a year.

Oh, and a minor thing: It might be a good idea to flush out all the "old" avgas, replace with new (or at the very least a mix of old and new) and run the engine on the ground at high power for a few minutes. As I understand the aging characteristics of avgas are quite good (better than mogas) but you still might suffer from gelling or deposits in the carbs, fuel lines and tanks after this long. Also check all drains, fuel selectors and fuel cutoffs to see if they're not seized up.

You also might want to recharge the battery on the bench using a suitable charger, rather than do that while the aircraft is flying. And check tire pressure and so forth.

definitely some long-ish high power ground runs, and change the fuel- or at least make sure the majority is fresh !

The engine is basically a VW. If you had parked your car up for a year would you expect it to work (provided the batt was new)? Of course you would! There has been a lot of scare mongering lately that any aircraft that has not flown for a year is scrap. My experience is that even after 5 years there is generally very little wrong. Run it up several times, check compressions etc. If you are happy, do one circuit and check everything is still ok. If so fly around locally for an hour or so keeping a close eye on the t’s & P’s. Check it over again and consider changing oil etc.

As above you need to make sure the fuel system is OK, as this is much more likely to catch you out.

Rod1

Many thanks everyone... really helpful posts :ok:

and then you tell people to run the engine on condition... I hope you fly a twin.

Obviously it depends on the storage.

I have a workshop at home, with loads of steel tools. I don't expect these to be rusty after 5 years, and they won't be.

But if I put them in the garden shed, which is the equivalent of a plane in an essentially unheated hangar, I would expect them to be rusty within a year or two, and they definitely will be.

Engines left around like that will be rusty inside. Not everywhere, but in areas where the oil has run off. About 10 years ago, a well known European a/c mfg stored a load of IO540 engines for 1-2 years past the limit date, before installing them. Most of the owners later found heavy corrosion. One I know personally nearly got a seized engine; I saw the photos of the cylinders. But it didn't happen right away; it took some months. I was one of the lucky ones; I got it only below the oil control rings, more or less, and in the SB569A job it all honed out OK.

It can happen below the top ring so just poking a borescope in there may not reveal it unless one looks carefully, turning the engine over.

Camshafts are prime candidates for corrosion too. And when they start wearing, they go fast. Remember that IOW 4xfatal PA28 crash? Their valve lift was 40% down, due to a knackered camshaft. Other mistakes were made but being well below book power didn't help. And you can't inspect the cams (on those engines) with a borescope.

Car engines cannot be compared directly. They have less outside air getting inside them. They have a long exhaust system, and a decent air filter.

The reason some people think this is OK is because most GA participants fly so little that it is usually somebody else, down the line of ownership, who picks up the tab for a knackered engine.

It's not just the camshaft that are susceptible to corrosion, cam followers also need looking at if doing an inspection.

When the camshaft starts to go, the follower surfaces start to break up, or vice versa.

Following advice on this thread I did a thorough check of the Limbach. No corrosion seen but the two left cylinders had a splendid 100 psi compression, while the two right cylinders had less than 10 psi. After difficult start and gradual warm up to working temp I did a couple of fast taxy runs (and hops) on the long runway. Returned to the hangar, changed the oil which was somewhat dirty, but no metal in the filter. The next compression check however made my day, as three cylinders registered 100 psi and one 85 psi. I guess there was some crud around the valves which burned off. Anyway with new oil, new plugs, and healthy compression time to take it into the air.

Now that you woke the airplane up, give some thought to getting yourself ready to fly.

The airplane needed some work to return to service; you should to. It's a good time to get with an instructor and do a flight review, before going flying on your own.

<< It's a good time to get with an instructor and do a flight review, before going flying on your own. >>

Funnily enough my local instructor just happening to be leaning on the ATL wing when I finished working. Seems I need 12 hours flying before June 7th to validate my PPL, and "When did you last practice EFATOs ?"
Guess my next flight will not be solo :hmm:

Good call. You'll be glad you did.

Flying skills are perishable. We can all use a little instruction.

I fly for a living, and have been doing that since I was a teenage kid. I've been going back for recurrent instruction on a regular basis for several decades now, and I always learn something new, and I always appreciate the dual.

A long time ago I was gone for two years, not flying. When I left, I wore the airplane like a second skin. I thought something and the airplane did it. When I came back, I didn't feel any different, but when I got in an airplane with a flight instructor, I learned that I thought one thing, and the airplane did something else.

No matter how much flight time we have, we can still use more training and regular recurrent checks. Think about it this way: if professionals flying for a living need it regularly and benefit from the insight oversight, and review, what does this say for all of us? Never turn down a chance to get some good training.

I'm a licensed skydiver. I've been away from parachuting at times for a period of time. Even though I'm licensed and have my own equipment, and even though the FAA has no regulations specifying currency, I always seek out a jump instructor and get some training before I jump again. I'll go through packing, emergency procedures in a harness, and make one or two jumps with an instructor before I go on my own. Take training whenever you can. None of us think we need it; we feel just the same, we feel like we remember everything, we feel it's like riding a bicycle, right?

Enjoy the training and the time. There's plenty of time to get your airplane some lift when you're done.

If it was Cliff, I hope you made him clean the wing! I know your ATL (by sight) and it's immaculate. If i were current I'd soon offer to do 10 or 12 hours for you- to ease your mind like!:ok:

CG