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A couple of years ago, I was running an engine with my stepson looking
on. He noticed a fine spiderweb appearing area near the prop hub, and
asked about it. I hadn't noticed it, but later wondered if it was the
beginning of a fracture. I replaced the prop immediately, haven't
given it any thought until this shread started.<br>
(APC 16-10)<br>
Bill Glaze<br>
<br>
<a class="moz-txt-link-abbreviated" href="mailto:RUDDERCABL@aol.com">RUDDERCABL@aol.com</a> wrote:<br>
<blockquote cite="mid199.455643a3.3033f955@aol.com" type="cite">
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<div>In a message dated 8/16/2005 12:51:26 AM Eastern Standard Time,
<a class="moz-txt-link-abbreviated" href="mailto:DaveL322@comcast.net">DaveL322@comcast.net</a> writes:</div>
<blockquote
style="border-left: 2px solid blue; padding-left: 5px; margin-left: 5px;"><font
style="background-color: transparent;" color="#000000" face="Arial"
size="2"><font face="Arial" size="2">With the 2 failures on 2Cs (both
well used props from the original mold), I'm personally going to limit
the number of flights I put on a given prop and retire some of my old
ones. Perhaps my thinking is flawed or too aggressive, but I don't
think it unreasonable that a high performance prop in a high
performance application has a limited life expectancy. <br>
<br>
Regards,<br>
<br>
Dave Lockhart</font></font></blockquote>
<div> </div>
<div>I agree with that. The prop that I had fail was an old prop with
many flights. It was used as a test prop and flown on many different
setups before and after Dave repitched it. I really liked the prop and
want another. Dave, you got one handy?</div>
<div> </div>
<div>I want to take this opertunity to say that I don't blame APC or
Dave for the failure. </div>
<div> </div>
<div>My memory may not be as good as I want it to be, but I think it
was Brian Hebert and Todd Blose that I was telling about the failure
while at the Nats. They told me they had seen a couple of failures on
some 2 blades also. The common thread was that they were old props.
Todd and Brian had already made the decision to replace their props on
an annual basis.</div>
<div> </div>
<div>After much thought, I am now of the opinion that many of us
(including myself ) have a tendency to tighten the props too much when
we put them on our engines. In the past, I have seen people tighten
them so much that it was a real bear to remove the propnut. Over
tightening them has got to have a crushing effect on the hub. Over the
life of the plane the prop is on, it can be removed and replaced many
times for maintenance or engine changes. It is not unreasonable to
believe that each time the hub is tightened down and then later
removed, a cycle has occured where the fibers and resin of the prop
have been squeezed and relaxed. Over time this could lead to small
cracks that may not be visible that are inside the hub. At this point,
failure is only a matter of time. </div>
<div> </div>
<div>Robert Gainey </div>
</font></blockquote>
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