On 1 Nov 2005 16:32:38 -0800, wrote:

50 rpm here or there are irrelavant.

Except for the extra centrifugal forces on the propeller. Some prop
manufacturers demand a visual inspection of a prop when overspeeded
(typically under 10% overspeed), and that the prop be removed and sent
in for NDI when more than 10% overspeed. A 10% overspeed translates
into 21% higher forces on those blades, and cracking can start.
The real danger is the aging tachometers; they tend to under-read,
and if it's indicating 50 RPM higher it might actually be 200 RPM
higher. Here in Canada we have to check them yearly, and any more than
4% error in the centre of the cruise RPM range means the tach gets
replaced.

Dan

This is also true of the engines. I forget the details, but when I
had an overspeed a few years ago I researched it and Lycoming had
parameters for 10% or less above rated power and over 10%. I do
remember that the over 10% is a very expensive "prop"osition and I
think required some sort of tear down for the engine. You can find
the info on their site.

z