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My Woodcomp propeller (the one I need to modify) is William Mills old one
(it was not fitted to his aircraft at the time of his accident). It is about
three years old and was probably one of the first to be fitted in the UK.
For the avoidance of doubt these propellers are definitely fitted with an
end stop mechanism. If you look at the photo there is a machined groove to
the right of the bronze coloured cog. There is an M6 bolt through the front
of the hub which locates in the groove limiting the blade travel.
The problem is that this prop has the facility for reverse thrust so the end
stop is of no use if the motor takes the blade beyond fine pitch. Thats why
I need to get it modified. I assume that your propeller Jos will have been
the same.
To say that there is no mechanical stop is untrue. The majority of Woodcomp
propellers have a shorter groove which limits the travel between coarse and
fine (or fine and feathered if it is the feathering variety). Anyone with a
"normal" Woodcomp prop has nothing to worry about in this respect.
If a motor burns out you have to question whether it was protected properly
with the correct rating fuse. If the motor is subjected to extreme demands
it will draw more current and blow the fuse before the windings failed. Were
such a failure occurr with the normal mechanical stop arrangement the
propeller would still be in the normal range, continue to produce thrust and
the aircraft should be flyable.
Knowing what I know now I would still buy the Woodcomp propeller again but I
would not fit a propeller (of any make) that didnt have mechanical end
stops.
Variable pitch propellers carry additional risks (compared to fixed). So
does flying!!! All you can do is try and minimise them.
The moral is dont fly with a prop that can go into reverse - it isnt worth
the doubtful advantages.
Carl Pattinson
G-LABS
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