What is "overspeed" on a fixed prop?

Same thing it is on a constant speed prop: the engine exceeds its maximum
allowed RPM.

Let me try that again. How can you overspeed an engine with a (properly)
fixed pitch prop?

"Max RPMs" on an O-320 (and, in fact, all aircraft engines) are so
retarded that the engine is really just loping along at 2700 rpm.

That's simply not true. In fact, the engine manual for any engine has
very specific guidelines about what the true maximum RPM is and how much
you can exceed that for how long before requiring some kind of
maintenance. These numbers are not far above the indicated redline.

I'm just passing along what my A&P has told me. He's got 42 years in the
engine rebuilding business, and is an award winning home builder and antique
aircraft restorer. According to him, our Lycoming/Continental engines are
purposefully designed to be slow-turning engines -- even at full throttle --
in order for them to survive all the way to TBO.

There is no harm running an O-320 with a fixed pitch prop at full throttle.
You'll make more noise, burn more gas, and go (a little) faster.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"