Today's Message Index:
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1. 05:43 AM - Re: Securing Muffler Springs (Watkinsdw)
2. 02:05 PM - Re: Securing Muffler Springs (Gary Aman)
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Subject: | Re: Securing Muffler Springs |
I, too switched to SS springs on my 912 ULS with its Titan exhaust. Stainless
Steel springs cured the problem of periodic breakage, although I only flew it
about 50 hours after the installation before it was sold. It was always a pain
when doing pre-flight and noticing that I needed to replace a spring, assuming
I missed it on the post-flight inspection.
Here's another twist- at one point, I noticed that the tangs on the exhaust system
that the springs hooked to showed considerable wear from the vibration, and
I had two of them tig welded to build them up as soon as I noticed it. It's
worth checking, because that would be another way to lose a spring and the safety
wire connection as well. If you use high temp goop on both ends of the spring
where it connects to the tang, any wear could go unnoticed.
Dave Watkins
Pompano Beach, Fl
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=455477#455477
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Subject: | Re: Securing Muffler Springs |
stainless steel springs give an added margin of saftey.From JBM.
> On Apr 25, 2016, at 2:38 PM, KIRBY, DENNIS T GS-13 USAF AFMC AFNWC/EZS <dennis.kirby.3@us.af.mil>
wrote:
>
>
> Kolb Friends -
>
> I'm sharing with you a tip that may prevent you some grief that I encountered
recently on my Mark-3. One of my muffler springs broke on a recent flight and
departed the engine. Went thru my Powerfin prop and it took a bite-sized chunk
out of the leading edge of one prop blade. Damage was beyond repair - cost
of a new blade was $250.
>
> All 8 springs on my Rotax-912 muffler are safety-wired, per common practice intended
at securing the spring when (not if) they break. I always check the safety
wire on each muffler spring as part of my preflight. Apparently on this
day, one of these safety wires was worn partially through and still appeared
secure when I checked it. When the spring broke in flight, the instantaneous
energy must have been sufficient to break the already-weakened safety wire, resulting
in the spring's departure from the engine. Double failure.
>
> So, here's the tip: I will no longer rely on ordinary safety wire to secure
my Rotax muffler springs. I've upgraded to 1/16" braided cable to secure these
springs. This is bicycle brake cable, available at any bike shop. I use one
piece (about 10 inches long) for each pair of springs. The cable ends are joined
and secured using a swaged ferrule. Cheap, easy to install, and most of
all, WAY more secure than a single strand of .032 safety wire! Constant engine
vibration will not wear thru it, as it does on safety wire.
>
> Fly safely ...
>
> Dennis Kirby
> Mark-3 / 912ul
> Sandia Park, NM
>
>
>
>
>
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