"tony roberts" wrote in message
news:nospam-5887C9.22294723102004@shawnews...
One week

If you can 't fly it every week, pickle the engine.

That's just silly.

Yes, a week is short enough for corrosion to occur. A few hours is, for
that matter (and that's the literal answer to the original question), and of
course every day you go without flying incurs additional damage.

But honestly, you obviously don't own an airplane. No owner would seriously
consider pickling the engine for a mere week of downtime. Most owners
wouldn't go to that much trouble for less than a couple of months or more of
downtime. It's just not practical.

Anyway, to the original poster: as I said, as you asked "before it *begins*
to deteriorate" (emphasis mine), the answer is a few hours after shutdown.
Corrosion is a constant process, and the longer you go, the worse it is.

It would be best for an airplane to be flown at least once a day, if not
multiple times a day. A week's not bad, nor are two. Beyond that, you are
likely going to see noticeable long-term effects on maintenance and engine
life.

You may be able to minimize the effects by using certain oils (Exxon claims
to have an oil that nearly eliminates corrosion even after long periods of
time), or that might just be marketing hype. I'm not aware of any unbiased
tests that would indicate one way or the other.

Pete