Long term storage damage

Some seals will be easier to replace before you mount it and find out the hard way.

While we are on the subject.  I have most of my leaks stopped but one good one still eludes me.  Oil seams to be all around the water pump area. Is there a seal down there somewhere?

For water pump seals, see Figure 1 and Paragraph 1.5 "Note" at:

https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si912001.pdf

Bill, actually, I started this topic to educate myself and others. I always wonder why when I read things like the 24 month storage limit.  So when an acquaintance of mine recently told me he was considering buying a kit aircraft- one I am familiar with- well, after looking at a few pictures I knew it was a kit manufactured many years ago- and for many reasons is just now ready for registration and airworthiness inspection. Unfortunately after checking the engine serial number it appears the engine was bought at the same time as the kit. The engine was manufactured in 2007 and according to the seller has 0.5 hours run time since new.  The seller (not the builder) has no other information on the engine.  I told him about the 24 month limit but couldn’t tell him why, nor could I even offer a guess at what kind of discount he should request from the seller if he was willing to take the risk.

In the case that you describe, I would say to just assume it will need a new engine.  That will be the discount to ask for, in all fairness.

I am curious.  Has the engine been installed on the aircraft?  If so, is it actually awaiting an airworthiness inspection with an engine that no one has ever seen running?

Hi All

The correct read on the Rotax material is 12 months in the original container with all sealing in place and stored in climate control.  After that you are to remove the bag and open the seal plugs enough to allow hand turning of the engine for a few turns to be sure that the oil is not sticking on the cam and crank with rods.  Repack and do this every 3 months up to a max of 24 month storage total time since new.  At this point we must consider that the original test run done at the factory would have deposited oils in all the critical places.  It is possible that these oils are now drying and may not be sufficient to lubricate/protect the engine while sitting.  

At the very least you need to remove the engine from the box and (if you're qualified) remove the gearbox assembly and check all the gear surfaces for corrosion, you don't need to disassemble it just look at the gear faces as this is where corrosion would be seen first.  Next you need to check for corrosion on the cam and crankshaft.  The easiest way for this is to remove one cylinder head and cylinder.  With a borescope check the internal parts for signs of visible corrosion.  If you find no corrosion the next step is a bit tricky.  We now must mount the engine on a suitable stand and feed oil into the oil pump and crank the engine to lubricate the rotating parts with clean fresh oil.  Once done rebag and place it back in the box...repeat as needed after another storage round.  

I know that some will ask where is this found?  Well the Rotax requirement is to return the engine to a qualified shop and they will follow this procedure after the 24 months.  If you have a particularly old engine they may find signs/reasons that it has to be fully split and all new seals and O-rings.  In that case the engine has to be set up on a test stand and re-run with a hot test before return.  As you can imagine there are few facilities capable of this work and considering your investment it may be good value to consider doing it that way.  Also think about all the SB and other updates that might be needed on older engines sitting long term.  

Cheers