Steve Barker wrote:
HEY I am merely the messenger. That's what the leading prop rebuilder in
the US told me 15 years ago. I have no reason to doubt him.


It's an old wives's tale.

Try to duplicate your aluminum prop "flexing" in your shop and report
back with the results.

AND, there is always a prop rebuilder better than your guy. Or my guy.
"Leading prop rebuilder" is a pretty brash & open-ended statement.

Rob