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1. 06:20 PM - Re: Engine Mischief (Lloyd & Lorrie Cudnohufsky)
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Jim, Mike & Fellow Kitfox Listers,
An update on the engine Mischief,
Looking through the Heavy Maintenance manual and some on-line research I
found other that experienced similar problems,
Dove into the wiring and discovered one of my grounding leads from one of
the modules has a crack in the insulation, one trigger wire has the
insulation worn through in one spot, and the 2 power leads from the ignition
coils both had strands broke at the crimps of the OEM quick connects,
probably from vibration. The ohm rating of these leads is listed to be 4.5
ohms, through the quick connect they were 6.5 ohms, once I cut the quick
connects off I got 4.3-4.5 ohms. Also decided to check the trigger clearance
while I was there, book says .012-.016". My clearance is .009-.010". More to
come, in the process of repairing the wiring then I'll tackle the trigger
clearance.
Thoughts, advise welcome,
lloyd
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of James Shumaker
Sent: Monday, August 19, 2013 10:26 PM
Subject: Re: Kitfox-List: Engine Mischief
I had vapor lock that was like that. Happened enough that I could predict
it on a climb out in warm weather. Shielded the gascolator from the exhaust
with a sheet of aluminum and have not had the same problem.
There is no problem with turning off one of the ignitions in flight. If you
turn off both you should pull the throttle to idle before restarting.
Jim Shumaker
Kitfox III Rotax 912, 1200 hours
From: Lloyd & Lorrie Cudnohufsky <7suds@Chartermi.net>
Sent: Monday, August 19, 2013 7:32 PM
Subject: Kitfox-List: Engine Mischief
List,
I have been enjoying my Model 5 a lot this summer, even managed to squeeze
in a flight into Airventure, but 2 weeks ago my daughter and I dropped into
a small strip north of here to do some Blueberry Picking. When we were
climbing out to leave the engine (912ul) lost power slightly, I pitched the
nose down, pulled the power and pushed it back in and it was fine. Headed
straight home (20 min flight) with no further problems, the change in power
was so slight my daughter never noticed anything was wrong, but I noticed.
Not sure why I did what I did, but it worked. (I also have an electric
booster pump in-line like Lowell described with the switch next to the
throttle, never even thought of using it). Not sure what it was I
experienced, it almost sounded like I fouled a cylinder for a moment or the
throttle slipped, but was a different sound than just reducing the throttle
(not a slip of the throttle, my hand was on it). So last week I pulled the
plugs, 50 hours on them, black sooted in front cylinders, golden brown in
the rear, put in all new plugs, checked all plug wires. Pulled the carb
bowls to look for debris, they were clean, visuals on everything else was
normal. So I put it back together. Then last weekend I was giving my
daughters friend a ride, we were in normal cruise attitude turning about
4500 and it happened again, I repeated the same procedure and it went away,
again, my passenger never noticed anything wrong.
So, thinking it through and replaying the events in my head I am leaning
towards what I actually experienced was dropping one of the ignition systems
and the power loss was the 100 or so rpm drop.
Now trying to troubleshoot, prove / disprove my theory, wondering if anyone
has had any experience troubleshooting intermittent ignition? Where to
start, what NOT to do, Here is my thoughts,
1) Start with a thorough inspection of all ignition wiring, terminals, key
switch remove tie wraps and bundling, chafe wraps etc, look for cracks,
arcing etc.
2) Review manual for any ohm checks I can make on the coils, ignition
systems, etc. Seeing the problem has been intermittent I am doubtful this
will turn up anything. Seems strange that reducing the throttle and then
increasing again cures the problem, broken wire, shaking?
3) If these steps turn up nothing I am considering taking it up, staying in
the pattern at altitude and turning off one ignition to see if that is what
I experienced, has anyone ever turned their ignition from both to one during
flight? Anyone see any concerns?
4) After all that, if I am unable to find or recreate the problem, buy one
ignition and change out one????
Appreciate any direction I can get,
Lloyd C KF 5 Outback
912ul IVO IFA Northern Mi
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