Today's Message Index:
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1. 09:16 AM - Re: Re: [Pulsar-Aviators] New Stator Coil In - Flying Again (dougwitkowski@netscape.net)
2. 08:16 PM - parts (Rex Miller)
3. 08:25 PM - Have great time in LWC! (Casey King)
4. 08:25 PM - Have great time in LWC! (Casey King)
Message 1
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| Subject: | Re: [Pulsar-Aviators] New Stator Coil In - Flying Again |
Ron,
Great discussion!
I assumed that failure on shutdown was 'common' knowledge as it was told to
me by both Green Skys and Leading Edge folks. Never really delved into th
e 'why' of how the failures are claimed to happen.
You are probably right in that it's not a voltage spike. More likely stres
ses caused by the grounding action.
The charging coil will experience a mechanical jolt and a momentary high cu
rrent flow when the coil is grounded. That could fatigue the coil or chafe
the insulation.
There is also a bridge rectifier between the charging coil and the capacito
r. It has to hold back the voltage as it's built in the capacitor with eac
h charging coil pulse. Even at the zero voltage point, there is resistance
in the charging coil. When the coil is grounded, the rectifier has to hol
d back what could be a full charge (before the system fires the plugs) agai
nst a zero resistance short. Either of these scenarios could be the cause
of a 'failure at shutdown' situation.
I doubt the capacitor or the SCR would experience any stress from the groun
ding.
Keep up the discussion at LWC, I'm sure it will be very interesting.
Doug W
-----Original Message-----
From: Ron Koval <ronko@att.net>
Sent: Tue, Aug 20, 2013 2:30 pm
Subject: Re: Pulsar-List: Re: [Pulsar-Aviators] New Stator Coil In - Flying
Again
Doug,
Forgive me for not having heard, ignition systems fail on shutdown. I find
that very hard to believe, understanding how they work and how we shut our
ignition down for mag checks.
In our CDI ignition system the stator coil charges up a capacitor, then a s
econd coil triggers an SCR (solid state device; silicon controlled rectifie
r) and discharges the capacitor into the ignition coil which has a step up
winding that fires the spark plug. All we do to shut this down is ground t
he very front end of the process, by grounding the stator coil so no charge
is provided to the module that houses the capacitor. Lycomings, Continent
al engines do the same except, they use the magnetic field of mag coil, ope
n a set of grounding points, which produces a sudden magnetic field change,
which then causes current to flow in the primary coil, and the secondary c
oil step up winding fires the spark plug. They also, at the front end, gro
und the primary coil using the P-lead to disable ignition. The only thing
that is getting beat up during a mag check is the mag switch.
Our ignition systems are not very susceptible to spikes or noise, because t
hey are the worst source, the culprit of the greatest transients and noise
in our aircraft.
With the faults that I have found at the connectors coupling the wires from
stator coil to the CDI module, the most likely root cause is vibration mec
hanically breaking the wire at the connector. I have one more side of the
stator coil to find out where it broke down. I am very anxoius to find thi
s other fault and protentially be able to fix it and have a back up stator
coil.
Best regards,
Ron
From: "dougwitkowski@netscape.net" <dougwitkowski@netscape.net>
Sent: Monday, August 19, 2013 10:06 AM
Subject: Pulsar-List: Re: [Pulsar-Aviators] New Stator Coil In - Flying Aga
in
Common knowledge is that ignition systems fail on shutdown (possible voltag
e spikes??). Testing pre-shutdown probably won't help, the testing itself
may cause the failure. In my mag check procedure, it's not the RPM drop t
hat's important, it's the return to normal RPM on 'both' that is important.
-----Original Message----- From: Ron Koval <ronko11@yahoo.com> To: Pulsar B
uilders <Pulsar-List@matronics.com>; Pulsar-Aviators <Pulsar-Aviators@yahoo
groups.com> Sent: Mon, Aug 19, 2013 9:50 am Subject: [Pulsar-Aviators] New
Stator Coil In - Flying Again
Pulsar Friends,
Put in the new stator coil in my 582 and ran it through 4 rounds of touch
and goes Sunday evening. Relief ... the Pulsar and I are looking forward t
o the convention.
After this experience, I learned and added a step to my engine shut down pr
ocedure, do a mag check. It is nice to know that you completed your flight
with both mags still working and if one ignition circuit, perhaps fails, d
ue to everything under the cowl at high temperatures, it is nice to know.
Also if this were perhaps the flight that one ignition circuit fails (more
likely to fail engine running than in the hanger), it is better to know now
rather than on the ramp wanting to take off per plan.
I discovered that in my defective stator coil there were 2 intermittent con
nections, right at the rubber 2 conductor connector of my defective stator
coil. I am on a mission to find out where the other side charging coil is
open. It would be nice to discover that it also has a simple connector wir
e problem and not an open within one of the 2 coils that make up the chargi
ng circuit.
Even after taking extra care to clean all of the contacts (grounds, power .
..) putting everything back together with the new stator coil, my analog ta
ch is reading way high. Fortunately my digital tach is what I reference.
Last time I fixed it, I added a stainless steel external tooth lock washer
on the heavy ground to dig into the metal surfaces and provide a good conne
ction to the engine block (but I cleaned this terminal again and still have
the lock-washer in place.
Looking forward to the convention.
Ronko
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Message 2
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I've got a mountain high o2 system for sale, model xrc 180, retail 450, wi
ll sell for 300, small and portable perfect for pulsar.
epoxy pump.
oil thermostat for rotax
8 spark plugs, 912ul
a few other things
thanks Rex
wish i could make larwance
Message 3
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| Subject: | Have great time in LWC! |
I too wish I could see everybody in KS. Next time I will! Look forward to hearing
reports.
Casey
Message 4
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| Subject: | Have great time in LWC! |
I too wish I could see everybody in KS. Next time I will! Look forward to hearing
reports.
Casey
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