On Jan 1, 4:41*pm, Mxsmanic wrote:
The POH for a number of small piston aircraft warn that high power and prop
settings should not be used for extended periods. *What counts as an extended
period, and what happens to the engine if these recommended (or mandatory)
limits are exceeded?

I got a good chuckle out of all the other answers. You guys are so
bad. g

Here's my crack at answering this question. To operate the engine
above and beyond it's design will result in premature engine wear and
tear. Also at or above the design parameters, the engine is not
getting adequate lubrication and/or cooling, again resulting in
premature wear and tear or possibly even cause engine seizure. This
wear and tear will also shorten the Time Between Overhaul TBO.

Monk