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Date: Wed, 13 Sep 2006 17:33:25 -0400
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Subject: Backfires
Thread-Topic: Backfires
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From: "Carl Cadwell" <CarlC@Cadwell.com>

Phil wrote: =20

Anyone had experience with this?
Pilot flying our IVP (TSIO550E3B with 4 blade MT) and reports:
"Had backfires(?) couple of nights back. Was running lean of peak with =20
temps 1590 at FL150, around -15C, light rain,  29Hg 2500rpm .
Happened twice so went rich of peak for remainder of flight with no =20
problems. Any reason come to mind?"
Be grateful for any thoughts

Phil Sexton
Melbourne


Thoughts:

I had the same occur although at FL240-250.  I believe what you are
hearing are not backfires (up through the intake system) but rather
afterfires from unburnt fuel in the exhaust that ignites in the exhaust.
And they are a real pucker factor.

2 probable causes.  1.  One or more of the cylinders are too lean of
peak.  I found that GAMI injectors solved that cause.  You can check
that by doing the GAMI lean test.  See this at www.gami.com under lean
test.

The second reason is that the Slick magento(s) is failing.  This was my
cause.  Upon inspection we found corrosion inside the cap of the
magento.  Slick stepped up and replaced the magnetos at no charge. =20

Carl Cadwell
N25CL IVP 940 hours, TSIO 550 E1B