The Murphy Builders Site

Folks,

I purchased a Moose with a Kimball air-start system that Brent Brown (of
Salt Lake) put together. With a little over 140 TT, lately the 3-blade
Harzell prop (HC-C3YR-1RLF/FJ9587C) turns very sluggishly, and even at
that will only turn 2 blades before just dumping air out the exhaust. I
get out, turn the prop a blade or so by hand, then the same thing. I
have good air pressure to start, ~750psi, but quickly run out and end up
hand-proping to start. There are no leaks in the system, as if I leave
the air on and come back the next day I still have upwards of 700psi.

I took out the ball-spring fitting on the bottom of the air distributor
and just put it in without the ball and spring; same thing.

It's a long story, but I just had to put a new engine on the plane. The
start symptoms are exactly the same as the engine I just took off, so
the problem is not with the distributor/engine.

1) Do you think that perhaps the solenoid on the firewall that (I think)
controls the release of air might be going bad (about 1 yr after
install)?

2) Does anyone have any insight on why the Kimball system doesn't have a
"snot" or dump valve for after one is on the ground to drain any water
in the system?

3) What else can I check/troubleshoot to help solve this vexing problem?

Thank you,

Ted Waltman




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It sounds like the solenoid
may not be opening all the way. I think Ryan had a problem with his
getting hot and not working. For that reason mine are not on the
firewall.

If it is the standard Kimaball setup you have two identical soleniods, on
e
for start one for dump overboard, you could try swapping them and see if
that is it.

Scott

Folks,

I purchased a Moose with a Kimball air-start system that Brent Brown (o

f

Salt Lake) put together. With a little over 140 TT, lately the 3-blade
Harzell prop (HC-C3YR-1RLF/FJ9587C) turns very sluggishly, and even at
that will only turn 2 blades before just dumping air out the exhaust.

I

get out, turn the prop a blade or so by hand, then the same thing. I
have good air pressure to start, ~750psi, but quickly run out and end u

p

hand-proping to start. There are no leaks in the system, as if I leave
the air on and come back the next day I still have upwards of 700psi.

I took out the ball-spring fitting on the bottom of the air distributor
and just put it in without the ball and spring; same thing.

It's a long story, but I just had to put a new engine on the plane. Th

e

start symptoms are exactly the same as the engine I just took off, so
the problem is not with the distributor/engine.

1) Do you think that perhaps the solenoid on the firewall that (I think

)

controls the release of air might be going bad (about 1 yr after
install)?

2) Does anyone have any insight on why the Kimball system doesn't have

a

"snot" or dump valve for after one is on the ground to drain any water
in the system?

3) What else can I check/troubleshoot to help solve this vexing problem

?

Thank you,

Ted Waltman




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Hi Ted,
This issue is of great interest to me too. The same thing has happened to
our M-14 start system which was also purchased from Kimball. I suspected
the solenoid. So I connected the air line going to the starter directly to
the air tank which was charged to 700 psi. The same problem still
existed--- slow cranking. I did clean the solenoid. I found a bit of crud
in the solenoid pilot valve. But that did not help. I had begun to think
that the problem may be in the air distributor but based on your tests, I
doubt it.. I wonder if the tank valve is too restrictive? That doesn't
seem too logical to me. I haven't pursued it further at this time. I hope
we can, collectively, get to the bottom of this problem. It's a real pain.
Dick Shotwell
Moose 096
N235DS
Twin Falls, ID

----- Original Message -----
From: "Ted Waltman" <tedwaltman@i1ci.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, April 17, 2005 14:33 PM
Subject: M-14 Kimball air start system question

Folks,

I purchased a Moose with a Kimball air-start system that Brent Brown (of
Salt Lake) put together. With a little over 140 TT, lately the 3-blade
Harzell prop (HC-C3YR-1RLF/FJ9587C) turns very sluggishly, and even at
that will only turn 2 blades before just dumping air out the exhaust. I
get out, turn the prop a blade or so by hand, then the same thing. I
have good air pressure to start, ~750psi, but quickly run out and end up
hand-proping to start. There are no leaks in the system, as if I leave
the air on and come back the next day I still have upwards of 700psi.

I took out the ball-spring fitting on the bottom of the air distributor
and just put it in without the ball and spring; same thing.

It's a long story, but I just had to put a new engine on the plane. The
start symptoms are exactly the same as the engine I just took off, so
the problem is not with the distributor/engine.

1) Do you think that perhaps the solenoid on the firewall that (I think)
controls the release of air might be going bad (about 1 yr after
install)?

2) Does anyone have any insight on why the Kimball system doesn't have a
"snot" or dump valve for after one is on the ground to drain any water
in the system?

3) What else can I check/troubleshoot to help solve this vexing problem?

Thank you,

Ted Waltman




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Would be really "FUN" if you were on floats now wouldn't it !?

----- Original Message -----
From: "Dick Shotwell" <dicks@filertel.com>
To: "Moose Builders" <rebel-builders@dcsol.com>
Sent: Sunday, April 17, 2005 7:37 PM
Subject: M-14 Kimball air start system question

Hi Ted,
This issue is of great interest to me too. The same thing has happened to
our M-14 start system which was also purchased from Kimball. I suspected
the solenoid. So I connected the air line going to the starter directly

to

the air tank which was charged to 700 psi. The same problem still
existed--- slow cranking. I did clean the solenoid. I found a bit of

crud

in the solenoid pilot valve. But that did not help. I had begun to think
that the problem may be in the air distributor but based on your tests, I
doubt it.. I wonder if the tank valve is too restrictive? That doesn't
seem too logical to me. I haven't pursued it further at this time. I

hope

we can, collectively, get to the bottom of this problem. It's a real

pain.

Dick Shotwell
Moose 096
N235DS
Twin Falls, ID

----- Original Message -----
From: "Ted Waltman" <tedwaltman@i1ci.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, April 17, 2005 14:33 PM
Subject: M-14 Kimball air start system question

Folks,

I purchased a Moose with a Kimball air-start system that Brent Brown (of
Salt Lake) put together. With a little over 140 TT, lately the 3-blade
Harzell prop (HC-C3YR-1RLF/FJ9587C) turns very sluggishly, and even at
that will only turn 2 blades before just dumping air out the exhaust. I
get out, turn the prop a blade or so by hand, then the same thing. I
have good air pressure to start, ~750psi, but quickly run out and end up
hand-proping to start. There are no leaks in the system, as if I leave
the air on and come back the next day I still have upwards of 700psi.

I took out the ball-spring fitting on the bottom of the air distributor
and just put it in without the ball and spring; same thing.

It's a long story, but I just had to put a new engine on the plane. The
start symptoms are exactly the same as the engine I just took off, so
the problem is not with the distributor/engine.

1) Do you think that perhaps the solenoid on the firewall that (I think)
controls the release of air might be going bad (about 1 yr after
install)?

2) Does anyone have any insight on why the Kimball system doesn't have a
"snot" or dump valve for after one is on the ground to drain any water
in the system?

3) What else can I check/troubleshoot to help solve this vexing problem?

Thank you,

Ted Waltman




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Hey guys. Just home from SNF and see there is a bunch of chatter about our
air systems. Two threads worth. We want to be included in the discovery
process with the systems. I have a billion emails to get through and things at the
shop to get up to speed on but will do all I can, as will Dad to help sort
this out for you.

The start and bypass valves are the same part number. The coils can vary
from time to time as there are several equivalent coils for 12 volt systems and
for 24 volt systems. There will be a part number both on the brass coil body
and on the black coil housing.

When trouble shooting the system, you can start at the tank. This will test
the tank shut off valve. Remove the hose from the bottle valve, crack the
valve and see if it blasts air freely. Next attach the hose to the bottle valve
again, disconnect the other end of the hose at the blue manifold and test that
hose and bottle by cracking the bottle valve again. If good there, attach
hose to manifold again, disconnect the hose at the start valve and with bottle
open, hit the start switch to open the start valve and see if you get a
startling blast. If good there, reattach the hose to the start valve and disconnect
it from the start spider. Ties that end of the hose down with a tie wrap and
hit the start again. If you get a good blast there, the only thing left is
the inlet valve of the spider or the spider. If you find an issue at any one of
these steps along, the way, determine the cause and let us know.


We have a specific bottle and valve we use in our air systems mounted
horizontally and the solenoid valves are at roughly the same elevation as the valve
in the tank. The low point in our system as we install it is the pop off
valve. So those of you who have different bottles or have them mounted in
different attitudes may see some variations in where the junk in the system tends to
settle. I don't know if this is an issue at all. Just a thought off the top
of my head because in the model 12s, we have had minimal issues with this given
the couple thousand flight hours accumulated thus far. When we do have air
system issues in the model 12 set up, it typically is on those airplanes where
the pilots do not use the bypass valve as we do. That being having the system
in bypass at all times except for a few minutes after starting while the
compressor boosts the system back to full pressure. We normally leave the air in
bypass until just before hitting the start switch.

We have one model 12 owner who wanted to conserve air at start. He put a
restrictor in the output fitting of the start valve with a .050" hole in it
instead of the full fitting ID of about .150" and found that the prop would spin
just as fast as a fully open fitting. The point here is that a restriction that
great did not make a noticeable difference in the spin speed of the prop.
So, if you see a reduction in spin rate, there is a near full restriction.

At any rate, I will get with Dad, we will look up the part numbers and help
in every way we can.

Sincerely,

Kevin Kimball, VP Engineering
Jim Kimball Enterprises, Inc.
PO Box 849, 5354 Cemetery Rd.
Zellwood, FL 32798
407-889-3451 phone
407-889-7168 fax
http://www.jimkimballenterprises.com/
http://www.pittsmodel12.com/




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Group,

I discussed the problems some of you are having with the air systems with my
father, Jim. Basically, he agrees with the post I made a few days ago
concerning the use of the bypass valve, how to troubleshoot the system, etc. He did
correct me on how our valves are mounted in the Pitts Model 12. They are at
the same elevation relative to the bottle valve as I mentioned but are not set
with the coils upright. The coil stem points forward toward the engine and he
did this to avoid having valve action at high g loads.

Visit this page: moose support page and click on the air system photo.
Working from the left end, you can see the fitting that will attach via hose to the
compressor. The left solenoid is the bypass valve and it has the through run
vertical with the output pointing down. The start valve has the run
horizontal with the output to the start distributor on the left. As you can see, both
solenoids have the stem and coil pointing horizontally toward the engine.
The bottle is horizontal as well.

What have you guys found with testing the system?

Sincerely,

Kevin Kimball, VP Engineering
Jim Kimball Enterprises, Inc.
PO Box 849, 5354 Cemetery Rd.
Zellwood, FL 32798
407-889-3451 phone
407-889-7168 fax
http://www.jimkimballenterprises.com/
http://www.pittsmodel12.com/




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