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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Mike,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>How old was the bearing? They’ll all self-destruct
eventually. If you pull on the prop blades and feel ANY roughness while you’re
rotating the prop back and forth, it’s time. When I used to run YS, one
season was about the best I could hope for on a main bearing. If I made it all
the way through without it failing the roughness test, I’d replace it
over the winter just to avoid having it go at an inopportune time the following
season.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Verne<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'> <o:p></o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <b>On Behalf Of </b>Michael
Cohen<br>
<b>Sent:</b> Friday, May 22, 2009 7:46 PM<br>
<b>To:</b> nsrca-discussion@lists.nsrca.org<br>
<b>Subject:</b> Re: [NSRCA-discussion] The good, the bad, and the ugly<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>For
those of you on the edge of your seat waiting to hear what was the likely cause
..... well....... a neighbor with a gear puller helped me pop of the
thrust washer and after removing the crank shaft, I found the main bearing
had eaten itself. The race had come apart and the balls we free
to slap around. The bearing probably went first allowing the
crank to wobble taking on the connecting rod. Bob Kane has come to
my rescue with pieces of Mark Atwood's old and damaged 160DZ. I will
attempt to make one running engine out of two.<br>
<br>
I have not heard of bearing failures with YS engines. I is there some
preventative maintenance I could have done to keep this from happening?
Did I make some mistake that leads to this kind of
failure? Is it just one of those things that is bound to happen one
of these days?<br>
<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif"'>From:
precisionaero@hotmail.com<br>
To: nsrca-discussion@lists.nsrca.org<br>
Date: Thu, 21 May 2009 04:58:52 -0600<br>
Subject: Re: [NSRCA-discussion] The good, the bad, and the ugly<br>
<br>
Low viscosity PowerMaster DZ blend, 30% nitro, 20% synthetic is the
fuel. I had replaced the ring a few months ago, so I had taken apart
most of the engine and re-assembled it using Klotz so it would not be
dry the first time fuel ran through it. By the way, I was 1.75 turn out on
the main needle. That seemed to be the RPM sweet spot +1/8 turn rich
for good luck. The pump was just right, the engine would chug along at
1900 RPM with a 4 blade nicely. I had a nice smoke trail too, almost
until the abrupt stop.<br>
<o:p></o:p></span></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;
font-family:"Verdana","sans-serif"'>Date: Wed, 20 May 2009 19:08:40 -0700<br>
From: getterflash@yahoo.com<br>
To: nsrca-discussion@lists.nsrca.org<br>
Subject: Re: [NSRCA-discussion] The good, the bad, and the ugly<o:p></o:p></span></p>
<div>
<p class=MsoNormal>Sorry to hear about your streak of bad luck. What kind
of fuel? Was the engine stored with after run oil? <o:p></o:p></p>
<div>
<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal>Bob Kane<br>
getterflash@yahoo.com <o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> Michael Cohen
<precisionaero@hotmail.com><br>
<b>To:</b> nsrca-discussion@lists.nsrca.org<br>
<b>Sent:</b> Wednesday, May 20, 2009 8:24:18 PM<br>
<b>Subject:</b> [NSRCA-discussion] The good, the bad, and the ugly<br>
</span><br>
The Good: I finally got out to fly today and put up flights 6 and 7 for
the season.<br>
<br>
The Bad: To say I practiced flying the Masters Pattern might not hold up
in court. It had looping segments (of various radii), straight lines
(some of very, very short length), roles (lets talk about mortgage rates
instead); in other words, it had all the basic elements. It also could be
argued that I was flying the Wonkavator, up ways and down ways, sideways and
back ways and slantways......<br>
<br>
The Ugly: 5 minutes into flight #2, the engine stopped. After a fun
crosswind glide, I took the engine apart at the field to find the
crankshaft-piston area very dry with shaving's everywhere, a mashed and
bent (sort of) connecting rod, and a damage to the rotary valve. I need
to take pictures and post them because I have never seen damage like
this. It looks like lubricating oil was unable to get into the region and
the engine just ate itself.<br>
<br>
This was my 160DZ and is on the heals of breaking the shaft that supports the
rocker arms on a 140DZ suddenly a month or so ago. Is there something
wrong with the lubrication system on these motors due to some kind of
blockage? Any suggestions on what to check would be appreciated.
The engines all looked clean and free of and kind of FOD when I took them apart
and re-assembled them this late winter/early fall. Before I go killing my
last 170DZ, I am open to what people think I should look for (beside an OS,
going electric, or gas).<br>
<br>
Mike Cohen<br>
D4<br>
<o:p></o:p></p>
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