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EDDY,
You mentioned RPM sag, I had been going through this problem since I
reinstalled my engine, I was dropping 300 RPM on takeoff or full power run
up, started at 5200 and dropped to 4900 before I got off the ground. I
checked with Tracey and he thought it might be plugs, as it turns out it was
timing. I had made my final timing adjustment with the timing light at 23
degrees before TDC but had only run the engine to 4000 RPM and had not payed
any attention to the manifold pressure . I have since retimed with the
manifold pressure at 22.3 " RPM 4250, since then no sag, now holds 5200 RPM
on takeoff and has a lot more balls. Tracey had said the manifold pressure
must be over 22" regardless of the RPM.
Jim Mosur
----- Original Message -----
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, September 24, 2003 5:24 PM
Subject: [FlyRotary] Re: Coil problem or is it?
>
> ----- Original Message -----
> From: "Tommy James" <twjames@healed.org>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Wednesday, September 24, 2003 6:55 PM
> Subject: [FlyRotary] Coil problem or is it?
>
>
> > Hi Guys,
> > Today I taxied out to test the mods made to my cooling system and ran
> right
> > into a new and unanticipated problem.
> > During the normal pre-take off engine checks, I selected "B" computer
and
> > then went to the coil disable switch. Pressing the switch in one
> direction
> > produced zero change, but the other choice produced a very noticeable
> > SILENCE. Duh? Never had that one before. Taxi back. Temperatures
stayed
> > around 170 during this 15-20 minutes of ground running with OAT <75*
> >
> > It was easy to isolate the faulty Leading coil as the culprit. I
talked
> to
> > TC who gave me the resistance values to check out 1. the resistor, 2.
the
> > coil, and a diagnostic procedure. Thanks, T!
> > Leading coil resistor and coil tested okay.
> >
> > Next we checked to make sure the EC2 was functioning okay by running a
> plug
> > wire to an extra plug clamped to the top of the block. Fire on both A
and
> B
> > for the leading coil. Double Duh!
> > Ran the engine again and the same thing happened again. Disabling the
> > Leading coil in "B" again shut the engine down.. Called TC again.
> >
> > Tracy suggested that it might be a plug problem. Triple Duh?! We
> changed
> > the leading plugs with plugs that had been cleaned with glass bead
> blasting
> > but were not new. The old plugs only had a couple of hours and looked
> okay.
> > No wear visible. A little carbon. Insulator clean.
> > Cranked her up and after adjusting mixtures on both A & B for about 2600
> rpm
> > we test the coils.. No Problem. a little more rpm drop on B, but
> > nothing major.
> >
> > Now, here are the pestering nagging questions: Why would relatively new
> > plugs fail when given the total load? Why would both plugs fail at the
> same
> > time? Is there something going on that is being overlooked? Has
anybody
>
> > else ever seen this happen? (Ed/ Eddie, are you there?) Did this
happen
> > because I'm so close to 2R4?
> >
> > Be easy, guys
> > Tommy James<><
> >
> >
> Hi Tommy,
>
> Yes, I HATE those kinds of things. If it want to fail, well OK. If it
> wants to fail on the GROUND, that's Great! But, if its going to fail, it
> should stay failed! I HATE intermittent and unexplained problems.
>
> Ok, thats off my chest. Here's a possibility, Tommy. I have noticed
> sometimes if I am running the mixture a tad on the lean side when I do the
> RPM check with "B" controller, the engine will not just change (normal),
but
> falter as if going to die. I hastely reach over and crank up the mixture
a
> notch and I am back in business. You don't say anything about mixture, so
> don't know if this could be a possible cause or not.
>
> Now when the "SAG" occurs, it apparently does affect both plugs. The EGT
> drops 300F on the effected rotor, rpm decreases around 150-200 rpm (if its
> just the one rotor, if you are so lucky as to have the SAG on both rotors
at
> the same time (happened to me once just after take off and before I got to
> pattern, the effect is more noticable like a 300-400 rpm drop. I climbed
> out at 500 fpm rather than my 1100+ so was not in any danger, but the seat
> cushion needed replacing. As, I say it gets your attention.
>
> Another possibility - because I misunderstood what Tracy meant when he
said
> you couldn't use straight wire for the spark plug leads to mean that I had
> to use resistor wires, I ended up with resistor wires and resistor plugs
> (the stock plugs are resistor type). All that appeared to hasten the time
> that the plugs were not apparently getting sufficient spark energy to
> reliabilty jump the gap. Once I elminated the resistor sparkplug wires,
> things improved considerably.
>
> I have had SAG with as little as 20 hours of 100LL on the plugs. I have
> gone as much as 50 hours, but the average is around 30 hours.
>
> Don't know if any of these could be the cause, but if it happens again,
> reach over and crank up your mixture control a notch and see if that does
> anything.
>
> Ed the EDDIE expert {:>)
>
>
>
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
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