Today's Message Index:
----------------------
1. 06:03 AM - Re: Lycoming service bulletins (Gary Casey)
2. 06:28 AM - Re: lean vs rich (Scott Bilinski)
3. 08:24 AM - Re: lean vs rich (Marvin Dupree)
4. 09:00 AM - Re: Re: plugs (Healy, Joseph)
5. 09:47 AM - Re: Lycoming service bulletins (Christopher Stone)
6. 10:43 AM - Re: lean vs rich (Scott Bilinski)
7. 07:24 PM - Re: Re: plugs (Lowell Fitt)
8. 08:48 PM - Re: Re: plugs (Johnny Johnson)
Message 1
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| Subject: | Re: Lycoming service bulletins |
--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
Steve - thanks for the great link! I maneuvered through the Lycoming
website and came up empty - they present a few SB's, but you have to pay $$$
for most.
Gary Casey
Message 2
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| Subject: | Re: lean vs rich |
--> Engines-List message posted by: Scott Bilinski <bilinski@kyocera-wireless.com>
Yes it is confusing, just the opposite of what you would think. When
peaking each cylinder one at a time the EGT's should peak about he same
temp right? So the only real difference is the fuel flow. I have to stand
by my previous post that the cylinder which peaks with the highest fuel
flow is the leanest, and yes its fuel flow for all 4 cylinders. Air Flow
Performance helped me dial in my fuel flow per cylinder. I gave them the
info they sent me the nozzles and installed them and it brought the fuel
flow closer together using this method.
At 08:40 PM 5/25/2004 -0400, you wrote:
>--> Engines-List message posted by: TeamGrumman@aol.com
>
>Quote: "Yea me to. Apparently the way it works is, the cylinder that peaks
>with the highest fuel flow, means all the other cylinders are getting more
>fuel
>so its the leanest. *** so the cylinder with the least fuel flow is the
>richest?=A0 somehow, I would have thought the opposite."
>
>I think someone is going to have to be a little more specific here.
>Cylinders with the highest fuel flow, i.e., receiving the most fuel, are
>the richest
>cylinders. Now, if you are saying that the cylinder with the first EGT to
>peak at any given fuel flow is the leanest, then I'd agree. I'm making the
>assumption that you are NOT measuring individual fuel flow rates for each
>cylinder.
>
>I admit I got in on this thread at the most recent email so if I am missing
>something, please feel free to let me in on what I'm missing.
>
>
Scott Bilinski
Eng dept 305
Phone (858) 657-2536
Pager (858) 502-5190
Message 3
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| Subject: | Re: lean vs rich |
--> Engines-List message posted by: Marvin Dupree <97corvette@cox.net>
scott....i questioned you on this earlier and from your response, i
thought i had it figured out. but, i read this one and i am still not
sure. are you saying that --- at highest fuel flow to all cylinders,
the cylinder that has the highest peak egt is the leanest----? or are
you saying the individual cylinder with the highest fuel flow is the
leanest?
regards, marv
On Wednesday, May 26, 2004, at 08:25 AM, Scott Bilinski wrote:
> --> Engines-List message posted by: Scott Bilinski
> <bilinski@kyocera-wireless.com>
>
> Yes it is confusing, just the opposite of what you would think. When
> peaking each cylinder one at a time the EGT's should peak about he same
> temp right? So the only real difference is the fuel flow. I have to
> stand
> by my previous post that the cylinder which peaks with the highest fuel
> flow is the leanest, and yes its fuel flow for all 4 cylinders. Air Flow
> Performance helped me dial in my fuel flow per cylinder. I gave them the
> info they sent me the nozzles and installed them and it brought the fuel
> flow closer together using this method.
>
>
> At 08:40 PM 5/25/2004 -0400, you wrote:
>> --> Engines-List message posted by: TeamGrumman@aol.com
>>
>> Quote: "Yea me to. Apparently the way it works is, the cylinder that
>> peaks
>> with the highest fuel flow, means all the other cylinders are getting
>> more
>> fuel
>> so its the leanest. *** so the cylinder with the least fuel flow
>> is the
>> richest?=A0 somehow, I would have thought the opposite."
>>
>> I think someone is going to have to be a little more specific here.
>> Cylinders with the highest fuel flow, i.e., receiving the most fuel,
>> are
>> the richest
>> cylinders. Now, if you are saying that the cylinder with the first
>> EGT to
>> peak at any given fuel flow is the leanest, then I'd agree. I'm
>> making the
>> assumption that you are NOT measuring individual fuel flow rates for
>> each
>> cylinder.
>>
>> I admit I got in on this thread at the most recent email so if I am
>> missing
>> something, please feel free to let me in on what I'm missing.
>>
>>
>
>
> Scott Bilinski
> Eng dept 305
> Phone (858) 657-2536
> Pager (858) 502-5190
>
>
> >
>
>
Message 4
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--> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
It seems that several people are having the same problem. For that
reason I doubt that an induction leak or other mechanical explanation is
the cause. If it were, then the discoloration problem would be random,
not consistently sooty front plugs with white back plugs.
The problem might be the pattern of cooling air under the cowl resulting
in a higher mass flow of air/fuel charge entering the front cylinders
compared with the rear cylinders. For example, if the air/fuel mixture
entering the front cylinders is at 75 degrees, and that for the rear is
105 degrees, the front cylinders will receive a 5% greater charge (more
fuel and air) than the rear cylinders. This is due to the increased
density of the air/fuel mixture predicted by the ideal gas law and
assuming a relatively equal manifold pressure at all points in the
intake. More fuel burnt in the front cylinders will contribute to more
soot on the plugs compared with the rear cylinders.
Also, if the intake manifold is experiencing a front to back
differential in temperature, then the cylinders will likewise have a
differential temperature front to back. The rear cylinders, being
hotter, will have more complete combustion and less soot than the front.
Note, this is not a question of too much cooling vs. too little cooling.
It is the differential cooling effect at various points on the engine
that would cause the problem.
Joe Healy
-----Original Message-----
From: kyle Ponsford [mailto:wild_kyle@hotmail.com]
Subject: Re: Engines-List: Re: plugs
--> Engines-List message posted by: "kyle Ponsford"
--> <wild_kyle@hotmail.com>
The intake manafolds connect the front and rear cylinders, and obviously
they are not perfect because I am learning lots of owners have collor
discrepency between front and rear. but do we know why?
> > Kinda hard to miss read a WHITE plug! and I do mean chalky white.
> > but no aluminum particles. the front plugs are so black and sooty
> > they foul at about 4 hours. it is hard for me to imagin guys flying
> > the things like that.
Message 5
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| Subject: | Re: Lycoming service bulletins |
--> Engines-List message posted by: Christopher Stone <rv8iator@earthlink.net>
I will send you a copy (.pdf) off list of the SI 1425a
Chris Stone
-----Original Message-----
From: Gary Casey <glcasey@adelphia.net>
Subject: Engines-List: Lycoming service bulletins
--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
I have been trying, with no luck, to find a copy of Lycoming Service
Bulletin SB388B and Service Instruction 1425A. Can anyone help?
Gary Casey
Message 6
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| Subject: | Re: lean vs rich |
--> Engines-List message posted by: Scott Bilinski <bilinski@kyocera-wireless.com>
Lets try this one more time. You look at one cylinder at a time, peak the
EGT, and note the fuel flow meter reading (which is all cyl fuel flow). Do
this on all cylinders. Look at the numbers and the cylinder that shows the
highest fuel flow, is the leanest. I put a larger nozzle in it and the
numbers come closer together. I really dont know another way to explain it.
At 10:22 AM 5/26/2004 -0500, you wrote:
>--> Engines-List message posted by: Marvin Dupree <97corvette@cox.net>
>
>scott....i questioned you on this earlier and from your response, i
>thought i had it figured out. but, i read this one and i am still not
>sure. are you saying that --- at highest fuel flow to all cylinders,
>the cylinder that has the highest peak egt is the leanest----? or are
>you saying the individual cylinder with the highest fuel flow is the
>leanest?
>regards, marv
>On Wednesday, May 26, 2004, at 08:25 AM, Scott Bilinski wrote:
>
> > --> Engines-List message posted by: Scott Bilinski
> > <bilinski@kyocera-wireless.com>
> >
> > Yes it is confusing, just the opposite of what you would think. When
> > peaking each cylinder one at a time the EGT's should peak about he same
> > temp right? So the only real difference is the fuel flow. I have to
> > stand
> > by my previous post that the cylinder which peaks with the highest fuel
> > flow is the leanest, and yes its fuel flow for all 4 cylinders. Air Flow
> > Performance helped me dial in my fuel flow per cylinder. I gave them the
> > info they sent me the nozzles and installed them and it brought the fuel
> > flow closer together using this method.
> >
> >
> > At 08:40 PM 5/25/2004 -0400, you wrote:
> >> --> Engines-List message posted by: TeamGrumman@aol.com
> >>
> >> Quote: "Yea me to. Apparently the way it works is, the cylinder that
> >> peaks
> >> with the highest fuel flow, means all the other cylinders are getting
> >> more
> >> fuel
> >> so its the leanest. *** so the cylinder with the least fuel flow
> >> is the
> >> richest?=A0 somehow, I would have thought the opposite."
> >>
> >> I think someone is going to have to be a little more specific here.
> >> Cylinders with the highest fuel flow, i.e., receiving the most fuel,
> >> are
> >> the richest
> >> cylinders. Now, if you are saying that the cylinder with the first
> >> EGT to
> >> peak at any given fuel flow is the leanest, then I'd agree. I'm
> >> making the
> >> assumption that you are NOT measuring individual fuel flow rates for
> >> each
> >> cylinder.
> >>
> >> I admit I got in on this thread at the most recent email so if I am
> >> missing
> >> something, please feel free to let me in on what I'm missing.
> >>
> >>
> >
> >
> > Scott Bilinski
> > Eng dept 305
> > Phone (858) 657-2536
> > Pager (858) 502-5190
> >
> >
> > >
> >
> >
>
>
Scott Bilinski
Eng dept 305
Phone (858) 657-2536
Pager (858) 502-5190
Message 7
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--> Engines-List message posted by: "Lowell Fitt" <lcfitt@inreach.com>
Joe's post pretty much explains the plug issue. The vast majority of the
engines in these configurations do not have baffling so the temp
differential will be there.
If the front plugs are fouling then my thought is that the mixture is too
rich. That won't take care of the white plugs on the rear, but as I have
said earlier, the color differential is not an issue for most 912 users. I
have heard Erik Tucker the recognized Rotax Guru speak on a couple of
occasions and this issue has never come up. My humble suggestion would be
to adjust the mixture to get a dark but not fouling sooty color to the
front plugs and go fly. Without a redesign of the induction system the
color differential will persist and I honestly don't think Rotax thinks it
to be a problem especially with the millions of hours on these engines.
If a problem arises, Rotax is also very quick to announce problems with
service bulletins. After only three or four instances with the stator
shorting, they provided free parts and free loner tools for upgrades. And
the problems that arose were with the certified version of the 912 used in
trainers. The free fix was never-the-less available to all.
Lowell
----- Original Message -----
From: "Healy, Joseph" <WJH@brplusa.com>
Subject: RE: Engines-List: Re: plugs
> --> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
>
> It seems that several people are having the same problem. For that
> reason I doubt that an induction leak or other mechanical explanation is
> the cause. If it were, then the discoloration problem would be random,
> not consistently sooty front plugs with white back plugs.
>
> The problem might be the pattern of cooling air under the cowl resulting
> in a higher mass flow of air/fuel charge entering the front cylinders
> compared with the rear cylinders. For example, if the air/fuel mixture
> entering the front cylinders is at 75 degrees, and that for the rear is
> 105 degrees, the front cylinders will receive a 5% greater charge (more
> fuel and air) than the rear cylinders. This is due to the increased
> density of the air/fuel mixture predicted by the ideal gas law and
> assuming a relatively equal manifold pressure at all points in the
> intake. More fuel burnt in the front cylinders will contribute to more
> soot on the plugs compared with the rear cylinders.
>
> Also, if the intake manifold is experiencing a front to back
> differential in temperature, then the cylinders will likewise have a
> differential temperature front to back. The rear cylinders, being
> hotter, will have more complete combustion and less soot than the front.
>
> Note, this is not a question of too much cooling vs. too little cooling.
> It is the differential cooling effect at various points on the engine
> that would cause the problem.
>
> Joe Healy
>
>
> -----Original Message-----
> From: kyle Ponsford [mailto:wild_kyle@hotmail.com]
> To: engines-list@matronics.com
> Subject: Re: Engines-List: Re: plugs
>
>
> --> Engines-List message posted by: "kyle Ponsford"
> --> <wild_kyle@hotmail.com>
>
> The intake manafolds connect the front and rear cylinders, and obviously
>
> they are not perfect because I am learning lots of owners have collor
> discrepency between front and rear. but do we know why?
>
> > > Kinda hard to miss read a WHITE plug! and I do mean chalky white.
> > > but no aluminum particles. the front plugs are so black and sooty
> > > they foul at about 4 hours. it is hard for me to imagin guys flying
> > > the things like that.
>
>
Message 8
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--> Engines-List message posted by: "Johnny Johnson" <Johnny@wiktel.com>
From a lurker that knows basically nothing about 912's but feels compelled
to comment... IIRC you said this happens on both sides, so maybe it is just
plain bad design of the intake runners or something. It sounds like a
pretty major difference in mixture and so just doesn't seem like it would be
designed to run that way... but, I may be all wet.
In any event and FWIW, I think I would want to be certain there are no
induction system leaks causing the lean mixture in the "white cylinders"
before I leaned it out some more. A bent or warped flange, loose fastener,
bad gasket, really lousy intake manifold to block fit, holes in a casting or
weld, something like that. It might be impossible to spot the culprit with
the Mk I eyeball--a way to check for leaks with the engine running has been
previously suggested but, as noted, can be a bit dicey with a prop
spinning... figuring a way to safely do that test would be well worth the
effort IMHO. Having satisfied myself that there are no leaks, I guess I
would then lean it a tad and go flying, as Lowell suggests.
Best of luck--hopefully you can get in the air very soon, with calmness of
heart :=))
Johnny
-----Original Message-----
From: owner-engines-list-server@matronics.com
[mailto:owner-engines-list-server@matronics.com] On Behalf Of Lowell Fitt
Subject: Re: Engines-List: Re: plugs
--> Engines-List message posted by: "Lowell Fitt" <lcfitt@inreach.com>
Joe's post pretty much explains the plug issue. The vast majority of the
engines in these configurations do not have baffling so the temp
differential will be there.
If the front plugs are fouling then my thought is that the mixture is too
rich. That won't take care of the white plugs on the rear, but as I have
said earlier, the color differential is not an issue for most 912 users. I
have heard Erik Tucker the recognized Rotax Guru speak on a couple of
occasions and this issue has never come up. My humble suggestion would be
to adjust the mixture to get a dark but not fouling sooty color to the
front plugs and go fly. Without a redesign of the induction system the
color differential will persist and I honestly don't think Rotax thinks it
to be a problem especially with the millions of hours on these engines.
If a problem arises, Rotax is also very quick to announce problems with
service bulletins. After only three or four instances with the stator
shorting, they provided free parts and free loner tools for upgrades. And
the problems that arose were with the certified version of the 912 used in
trainers. The free fix was never-the-less available to all.
Lowell
----- Original Message -----
From: "Healy, Joseph" <WJH@brplusa.com>
Subject: RE: Engines-List: Re: plugs
> --> Engines-List message posted by: "Healy, Joseph" <WJH@BRPLUSA.COM>
>
> It seems that several people are having the same problem. For that
> reason I doubt that an induction leak or other mechanical explanation is
> the cause. If it were, then the discoloration problem would be random,
> not consistently sooty front plugs with white back plugs.
>
> The problem might be the pattern of cooling air under the cowl resulting
> in a higher mass flow of air/fuel charge entering the front cylinders
> compared with the rear cylinders. For example, if the air/fuel mixture
> entering the front cylinders is at 75 degrees, and that for the rear is
> 105 degrees, the front cylinders will receive a 5% greater charge (more
> fuel and air) than the rear cylinders. This is due to the increased
> density of the air/fuel mixture predicted by the ideal gas law and
> assuming a relatively equal manifold pressure at all points in the
> intake. More fuel burnt in the front cylinders will contribute to more
> soot on the plugs compared with the rear cylinders.
>
> Also, if the intake manifold is experiencing a front to back
> differential in temperature, then the cylinders will likewise have a
> differential temperature front to back. The rear cylinders, being
> hotter, will have more complete combustion and less soot than the front.
>
> Note, this is not a question of too much cooling vs. too little cooling.
> It is the differential cooling effect at various points on the engine
> that would cause the problem.
>
> Joe Healy
>
>
> -----Original Message-----
> From: kyle Ponsford [mailto:wild_kyle@hotmail.com]
> To: engines-list@matronics.com
> Subject: Re: Engines-List: Re: plugs
>
>
> --> Engines-List message posted by: "kyle Ponsford"
> --> <wild_kyle@hotmail.com>
>
> The intake manafolds connect the front and rear cylinders, and obviously
>
> they are not perfect because I am learning lots of owners have collor
> discrepency between front and rear. but do we know why?
>
> > > Kinda hard to miss read a WHITE plug! and I do mean chalky white.
> > > but no aluminum particles. the front plugs are so black and sooty
> > > they foul at about 4 hours. it is hard for me to imagin guys flying
> > > the things like that.
>
>
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