Herb Sanders wrote:

Paul & Ed, As one who experienced a prop failure on first flight, please allow me to make a
comment. About 20 years ago at Sun & Fun I met a young man who had built a Long EZ and was a
graduate aeronautical engineer and was interensted in props Ron Lueck's dad had built the Air
Shark and Ron has gone on to develop the Comp Monster line of kitplanes.

    He offered to custom build me a prop he claimed would go several knots faster, I agreed to buy
one, and he built one and sent it to me in a couple of months. The improved efficiency was from
thin blades covered in kevlar for strength. On the first flight, I lifted off, made no unusual
pitch or yaw moves, climbed up to 1000 ft and stayed in the pattern. On the downwind at about 140
mph I developed a vibration and it got worse as I turned base, final, and slowed for landing.

    I landed and taxied to the ramp and a friend ran out and said my prop was smoking.  I shut
down, got out and looked over the prop. About a foot out from the center, both blades were broken
chordwise and you could take the tip and move the blades fore and aft about a foot. They were
retained only by the kevlar fabric and the smoke was from the heat/friction of the wood rubbing
together. (remember the Boy Scout trick of starting a fire rubbing wood together) My engine was
not retained by a cable and either of the blades departing would have been fatal according to Mike
Melville.

    When I was 20 years younger, I flew first flight on eight canards and did some flight testing
on new products for Sensenich Props and for Ben Ellison on the throttle body injector. I had a
total engine out from a mixture system failure in flight and the engine went to idle cutoff - I
was fortunate to land on a paved highway in Arkansas with no damage or injury.

    The point of telling you this is that in testing, some things pass the test and some fail. I
would really hate for you to look back the next day and think, was it really necessary to do in
flight testing on the new design, complex, high risk piece of equipment on the very first day it
was ever spun up?

    I have heard that God protects fools and drunks. Since my friend Ed is no fool, please get him
drunk if he flys this prop on the first day :-).

    I love and appreciate all that you do - just be careful.
Regards, Herb Sanders

 
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