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My opinion - for what it's worth - is that the
suggested limits on prop pitch cycling are similar to the limits for otherwise
cold engines.
When the prop is deep cycled it places a load on
the engine. Tolerances are not what they should be due to uneven
temperatures and the oil is not working as it does for continuous
operation. Consider the fit of a piston under this condition - The
cylinder may be out of round due to uneven heating, there is combustion on one
surface and cold oil on the other, then you load it so the RPM drops from 1800
to -what- 900? This puts a strain on the parts and drops the oil pressure
and flow too.
For our (Lancair) purposes, there is little or no
advantage to deep cycling and there may be the possibility of doing
harm.
Mark Ravinski
N360KB 1321 hrs
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