[NSRCA-discussion] The good, the bad, and the ugly

Fri May 22 20:22:15 AKDT 2009

Mike,

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.

Verne

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Michael Cohen
Sent: Friday, May 22, 2009 7:46 PM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] The good, the bad, and the ugly

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.

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?

  _____  

From: precisionaero at hotmail.com
To: nsrca-discussion at lists.nsrca.org
Date: Thu, 21 May 2009 04:58:52 -0600
Subject: Re: [NSRCA-discussion] The good, the bad, and the ugly

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.

  _____  

Date: Wed, 20 May 2009 19:08:40 -0700
From: getterflash at yahoo.com
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] The good, the bad, and the ugly

Sorry to hear about your streak of bad luck.  What kind of fuel?  Was the
engine stored with after run oil? 

Bob Kane
getterflash at yahoo.com 

  _____  

From: Michael Cohen <precisionaero at hotmail.com>
To: nsrca-discussion at lists.nsrca.org
Sent: Wednesday, May 20, 2009 8:24:18 PM
Subject: [NSRCA-discussion] The good, the bad, and the ugly

The Good:  I finally got out to fly today and put up flights 6 and 7 for the
season.

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......

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.

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).

Mike Cohen
D4

  _____  

HotmailR goes with you. Get
<http://windowslive.com/Tutorial/Hotmail/Mobile?ocid=TXT_TAGLM_WL_HM_Tutoria
l_Mobile1_052009>  it on your BlackBerry or iPhone.

  _____  

Windows LiveT: Keep your life in sync. Check
<http://windowslive.com/explore?ocid=TXT_TAGLM_BR_life_in_synch_052009>  it
out.

  _____  

HotmailR has a new way to see what's up with your friends. Check it out.
<http://windowslive.com/Tutorial/Hotmail/WhatsNew?ocid=TXT_TAGLM_WL_HM_Tutor
ial_WhatsNew1_052009> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20090523/017e6a8b/attachment.html>