Today's Message Index:
----------------------
1. 08:14 AM - Re: AC-680 FLP Engine RPM Fluctuation (willis robison)
2. 08:48 PM - Re: AC-680 FLP Engine RPM Fluctuation (Tom Fisher)
3. 09:05 PM - Re: AC-680 FLP Engine RPM Fluctuation (Don Barry Home)
4. 10:26 PM - Re: AC-680 FLP Engine RPM Fluctuation (nico css)
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| Subject: | Re: AC-680 FLP Engine RPM Fluctuation |
Well, Next time you fly, once youve leaned for cruise, check the EGTs for t
hose cylilnders that had the new lines welded.- If they are running withi
n a few degrees of the others, then he did a good job welding.- SS lines
with anything less than 130 thou. diam-are extremely hard to weld without
causing an "orifice" at the weldsite.-
-
-Also, I doubt that he-annealed the new weld, which will make the heat
affected zone-more brittle than the rest. Ask him how he treated the weld
.- (a smoky acetylene torch for- 2 minutes would be sufficient.
-
Bottom line, Mr.RPM should have is axxx chewed for sending you lousy parts.
You shouldnt have to do his Acceptance test procedures on your AC.
-
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, I am that much more informed, thanks for the info.
Tom
C-GISS
----- Original Message -----
From: willis robison
Sent: Monday, October 27, 2008 11:54 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Thanks Tom.
-
Ive designed a few fuel systems and his symptoms are typical of a flowdivid
er/lines on the hot side of an engine. (side downstream of an air cooled en
gine)-And-are-more prevalent with Lines that have a lot of volume.-
-
Im unfamiliar with Commanders, but from the looks of the cowl inlets on som
e of them,-it appears the cooling airflow is from bottom to top and then
out.- If not then there is a big air-dam that deflects cool air to the to
p of the engine and then down.- Either way, cooling appears greatly reduc
ed during climbout unless there are some big cown-vents downstream.
-
As-Ive seen it.
1.- larger dia. lines have a higher vapor/liquid ratio-during operation
, and on shut down, cook-off the remaining fuel in the FDV.- they are bet
ter, however on climbout as there is less pressure losses and heat absorbed
.- Modern FDV's have a purge valve that dumps fuel back to the inlet of t
he pump on shutdown.- this immediately drops the pressure at the nozzles
to zero...
-
2. smaller lines have shorter fill times, quicker starts but are susceptibl
e to vapor lock because they absorb heat faster.- At higher flowrates (ri
ch) the delta-P loss in these lines may result in a higher vapor/liquid rat
o- and thus a poorer spray patter at the nozzle.- This is more of an is
sue on climbout on engines with poor cooling for whatever reason (like clos
ed cowlvents, or just reduced airspeed (airflow)).- Modern fuellines in t
hese situations are insulated (just like grandpas truck).
-
3.- for systems with high flowrates (~100 pph or more) the different leng
ths of fuel lines from the FDV to each nozzle becomes important.- there a
re different pressure losses in each leg. (which makes GAMI's all the more
important.-)- If you want to save yourself the recurring cost of Gami i
njectors...get your flow divider valve balanced with your set of nozzles.
-
Just some thoughts.
-
wer
former Pratt-Whitney and Ham-STD
-
-
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
I got a new set from Mr.RPM himself so I assume they were of the same insid
e diameter and yes his lines leaked and had to be welded in two places. I j
ust replaced the lines from the flow divider to the cylinders.
Tom.
C-GISS
-
----- Original Message -----
From: willis robison
Sent: Monday, October 27, 2008 7:59 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Tom, did you replace the lines with ones of the same Inside diameter?- Di
d you replace those on both sides of the flow divider (spider), and the fue
l servo?
-
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
<tfisher@commandergroup.bc.ca>
I had the same surging problem on mine.
I replaced all the upper deck lines with new stainless steel lines, the new
lines also had to be welded in two places, this resolved the surging
problem.
Tom
C-GISS
680FLP (Mr.RPM)
----- Original Message -----
From: "Ray Mansfeld" <hcourier@cox.net>
Sent: Sunday, October 26, 2008 6:14 PM
Subject: Commander-List: AC-680 FLP Engine RPM Fluctuation
<hcourier@cox.net>
>
> Am having a problem with the left engine on the 680 FLP I fly (Mr. RPM
> Conversion). Takeoff is fine but on climb out the left engine RPM is
> unsteady, somewhat like a prop that won't stabilize. Here's some
info:
>
> 1. The problem seems to occur primarily during climb as I bring the
> turbos up (I've got manual turbos)
> 2. The fluctuation is random as to when it occurs and how much the RPM
> fluctuates...probably 10-20 RPM. Sometimes it's noticeable as
the
> aircraft yaws, sometimes it's not noticeable.
> 3. Sometimes it seems that leaning the mixture helps a bit but not
> always
> 4. I've also noticed that sometimes when the problem has occured on a
> flight that on shutdown of the engine after landing, it doesn't
want
> to
> stop running with the mixture pulled all the way to lean/idle-cutoff
.
> 5. Sometimes I the lean the mixture during the 1500 RPM ground check
> and the RPM goes up 50 RPM or so, sometimes it doesn't
> 6. Once I level off the problem seems to disappear or be almost
> un-noticeable. Although tonight I applied full rich mixture while in
> level
> flight at 4,500' and I could notice a slight RPM fluctuation if I
> paid close
> attention.
> 7. Fuel pressure is normal and turning the fuel pump on or off has no
> affect on the engine
>
> My thoughts:
>
> 1. I think the problem is in some fuel metering mechanism in the
> carburetor that is unsteady
> 2. At one point I thought there might be a leak in the turbo pressure
> lines causing a fluctuation in turbo air to the engine
> 3. Now, with the engine shut down problem (doesn't happen every time)
> I think there is a link between the turbo air (as I bring it up on
> climb)
> and fuel metering. They are probably interrelated.
>
> I've received help from many of you out there before. Has anyone had
this
> type problem occur and if so what might be the problem?
>
> Thank you,
>
> Ray Mansfield
> N91ES
> 850-217-5185
>
>
>
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| Subject: | Re: AC-680 FLP Engine RPM Fluctuation |
I do not yet have engine monitors but they are on the wish list.
Well he was out of the business and already sold the STC and as far as I
was concerned I was happy to receive the lines from him even if they had
to be tweaked by an expensive AME who did in fact anneal the welds, good
point.
Tom.
C-GISS
----- Original Message -----
From: willis robison
To: commander-list@matronics.com
Sent: Tuesday, October 28, 2008 8:11 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, Next time you fly, once youve leaned for cruise, check the
EGTs for those cylilnders that had the new lines welded. If they are
running within a few degrees of the others, then he did a good job
welding. SS lines with anything less than 130 thou. diam are extremely
hard to weld without causing an "orifice" at the weldsite.
Also, I doubt that he annealed the new weld, which will make
the heat affected zone more brittle than the rest. Ask him how he
treated the weld. (a smoky acetylene torch for 2 minutes would be
sufficient.
Bottom line, Mr.RPM should have is axxx chewed for sending you
lousy parts. You shouldnt have to do his Acceptance test procedures on
your AC.
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca>
wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
To: commander-list@matronics.com
Date: Monday, October 27, 2008, 2:17 PM
Well, I am that much more informed, thanks for the info.
Tom
C-GISS
----- Original Message -----
From: willis robison
To: commander-list@matronics.com
Sent: Monday, October 27, 2008 11:54 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM
Fluctuation
Thanks Tom.
Ive designed a few fuel systems and his symptoms are
typical of a flowdivider/lines on the hot side of an engine. (side
downstream of an air cooled engine) And are more prevalent with Lines
that have a lot of volume.
Im unfamiliar with Commanders, but from the looks of
the cowl inlets on some of them, it appears the cooling airflow is from
bottom to top and then out. If not then there is a big air-dam that
deflects cool air to the top of the engine and then down. Either way,
cooling appears greatly reduced during climbout unless there are some
big cown-vents downstream.
As Ive seen it.
1. larger dia. lines have a higher vapor/liquid ratio
during operation, and on shut down, cook-off the remaining fuel in the
FDV. they are better, however on climbout as there is less pressure
losses and heat absorbed. Modern FDV's have a purge valve that dumps
fuel back to the inlet of the pump on shutdown. this immediately drops
the pressure at the nozzles to zero...
2. smaller lines have shorter fill times, quicker
starts but are susceptible to vapor lock because they absorb heat
faster. At higher flowrates (rich) the delta-P loss in these lines may
result in a higher vapor/liquid rato and thus a poorer spray patter at
the nozzle. This is more of an issue on climbout on engines with poor
cooling for whatever reason (like closed cowlvents, or just reduced
airspeed (airflow)). Modern fuellines in these situations are insulated
(just like grandpas truck).
3. for systems with high flowrates (~100 pph or more)
the different lengths of fuel lines from the FDV to each nozzle becomes
important. there are different pressure losses in each leg. (which
makes GAMI's all the more important. ) If you want to save yourself the
recurring cost of Gami injectors...get your flow divider valve balanced
with your set of nozzles.
Just some thoughts.
wer
former Pratt-Whitney and Ham-STD
--- On Mon, 10/27/08, Tom Fisher
<tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM
Fluctuation
To: commander-list@matronics.com
Date: Monday, October 27, 2008, 10:57 AM
I got a new set from Mr.RPM himself so I assume they
were of the same inside diameter and yes his lines leaked and had to be
welded in two places. I just replaced the lines from the flow divider to
the cylinders.
Tom.
C-GISS
----- Original Message -----
From: willis robison
To: commander-list@matronics.com
Sent: Monday, October 27, 2008 7:59 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM
Fluctuation
Tom, did you replace the lines with ones of
the same Inside diameter? Did you replace those on both sides of the
flow divider (spider), and the fuel servo?
wer
--- On Mon, 10/27/08, Tom Fisher
<tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher
<tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP
Engine RPM Fluctuation
To: commander-list@matronics.com
Date: Monday, October 27, 2008, 7:34 AM
<tfisher@commandergroup.bc.ca>
I had the same surging problem on mine.
I replaced all the upper deck lines with new stainless steel lines, the
new
lines also had to be welded in two places, this resolved the surging
problem.
Tom
C-GISS
680FLP (Mr.RPM)
----- Original Message -----
From: "Ray Mansfeld" <hcourier@cox.net>
Sent: Sunday, October 26, 2008 6:14 PM
Subject: Commander-List: AC-680 FLP Engine RPM Fluctuation
<hcourier@cox.net>
>
> Am having a problem with the left engine on the 680 FLP I fly (Mr. RPM
> Conversion). Takeoff is fine but on climb out the left engine RPM is
> unsteady, somewhat like a prop that won't stabilize. Here's some
info:
>
> 1. The problem seems to occur primarily during climb as I bring the
> turbos up (I've got manual turbos)
> 2. The fluctuation is random as to when it occurs and how much the
RPM
> fluctuates...probably 10-20 RPM. Sometimes it's noticeable as
the
> aircraft yaws, sometimes it's not noticeable.
> 3. Sometimes it seems that leaning the mixture helps a bit but not
> always
> 4. I've also noticed that sometimes when the problem has occured on a
> flight that on shutdown of the engine after landing, it doesn't
want
> to
> stop running with the mixture pulled all the way to
lean/idle-cutoff.
> 5. Sometimes I the lean the mixture during the 1500 RPM ground check
> and the RPM goes up 50 RPM or so, sometimes it doesn't
> 6. Once I level off the problem seems to disappear or be almost
> un-noticeable. Although tonight I applied full rich mixture while
in
> level
> flight at 4,500' and I could notice a slight RPM fluctuation if I
> paid close
> attention.
> 7. Fuel pressure is normal and turning the fuel pump on or off has no
> affect on the engine
>
> My thoughts:
>
> 1. I think the problem is in some fuel metering mechanism in the
> carburetor that is unsteady
> 2. At one point I thought there might be a leak in the turbo pressure
> lines causing a fluctuation in turbo air to the engine
> 3. Now, with the engine shut down problem (doesn't happen every time)
> I think there is a link between the turbo air (as I bring it up
on
> climb)
> and fuel metering. They are probably interrelated.
>
> I've received help from many of you out there before. Has anyone had
this
> type problem occur and if so what might be the problem?
>
> Thank you,
>
> Ray Mansfield
> N91ES
> 850-217-5185
>
>
>
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| Subject: | AC-680 FLP Engine RPM Fluctuation |
MR. RPM is out of business?? I wonder whatever happened to that AC they were
playing around with the water-cooled Orenda engines.
Don
Houston TX
_____
From: owner-commander-list-server@matronics.com
[mailto:owner-commander-list-server@matronics.com] On Behalf Of Tom Fisher
Sent: Tuesday, October 28, 2008 10:46 PM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
I do not yet have engine monitors but they are on the wish list.
Well he was out of the business and already sold the STC and as far as I was
concerned I was happy to receive the lines from him even if they had to be
tweaked by an expensive AME who did in fact anneal the welds, good point.
Tom.
C-GISS
----- Original Message -----
From: willis robison <mailto:drwer2@yahoo.com>
Sent: Tuesday, October 28, 2008 8:11 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, Next time you fly, once youve leaned for cruise, check the EGTs for
those cylilnders that had the new lines welded. If they are running within
a few degrees of the others, then he did a good job welding. SS lines with
anything less than 130 thou. diam are extremely hard to weld without causing
an "orifice" at the weldsite.
Also, I doubt that he annealed the new weld, which will make the heat
affected zone more brittle than the rest. Ask him how he treated the weld.
(a smoky acetylene torch for 2 minutes would be sufficient.
Bottom line, Mr.RPM should have is axxx chewed for sending you lousy parts.
You shouldnt have to do his Acceptance test procedures on your AC.
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, I am that much more informed, thanks for the info.
Tom
C-GISS
----- Original Message -----
From: willis <mailto:drwer2@yahoo.com> robison
Sent: Monday, October 27, 2008 11:54 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Thanks Tom.
Ive designed a few fuel systems and his symptoms are typical of a
flowdivider/lines on the hot side of an engine. (side downstream of an air
cooled engine) And are more prevalent with Lines that have a lot of volume.
Im unfamiliar with Commanders, but from the looks of the cowl inlets on some
of them, it appears the cooling airflow is from bottom to top and then out.
If not then there is a big air-dam that deflects cool air to the top of the
engine and then down. Either way, cooling appears greatly reduced during
climbout unless there are some big cown-vents downstream.
As Ive seen it.
1. larger dia. lines have a higher vapor/liquid ratio during operation, and
on shut down, cook-off the remaining fuel in the FDV. they are better,
however on climbout as there is less pressure losses and heat absorbed.
Modern FDV's have a purge valve that dumps fuel back to the inlet of the
pump on shutdown. this immediately drops the pressure at the nozzles to
zero...
2. smaller lines have shorter fill times, quicker starts but are susceptible
to vapor lock because they absorb heat faster. At higher flowrates (rich)
the delta-P loss in these lines may result in a higher vapor/liquid rato
and thus a poorer spray patter at the nozzle. This is more of an issue on
climbout on engines with poor cooling for whatever reason (like closed
cowlvents, or just reduced airspeed (airflow)). Modern fuellines in these
situations are insulated (just like grandpas truck).
3. for systems with high flowrates (~100 pph or more) the different lengths
of fuel lines from the FDV to each nozzle becomes important. there are
different pressure losses in each leg. (which makes GAMI's all the more
important. ) If you want to save yourself the recurring cost of Gami
injectors...get your flow divider valve balanced with your set of nozzles.
Just some thoughts.
wer
former Pratt-Whitney and Ham-STD
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
I got a new set from Mr.RPM himself so I assume they were of the same inside
diameter and yes his lines leaked and had to be welded in two places. I just
replaced the lines from the flow divider to the cylinders.
Tom.
C-GISS
----- Original Message -----
From: willis <mailto:drwer2@yahoo.com> robison
Sent: Monday, October 27, 2008 7:59 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Tom, did you replace the lines with ones of the same Inside diameter? Did
you replace those on both sides of the flow divider (spider), and the fuel
servo?
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
<tfisher@commandergroup.bc.ca>
I had the same surging problem on mine.
I replaced all the upper deck lines with new stainless steel lines, the new
lines also had to be welded in two places, this resolved the surging
problem.
Tom
C-GISS
680FLP (Mr.RPM)
----- Original Message -----
From: "Ray Mansfeld" <hcourier@cox.net>
Sent: Sunday, October 26, 2008 6:14 PM
Subject: Commander-List: AC-680 FLP Engine RPM Fluctuation
<hcourier@cox.net>
>
> Am having a problem with the left engine on the 680 FLP I fly (Mr. RPM
> Conversion). Takeoff is fine but on climb out the left engine RPM is
> unsteady, somewhat like a prop that won't stabilize. Here's some
info:
>
> 1. The problem seems to occur primarily during climb as I bring the
> turbos up (I've got manual turbos)
> 2. The fluctuation is random as to when it occurs and how much the RPM
> fluctuates...probably 10-20 RPM. Sometimes it's noticeable as
the
> aircraft yaws, sometimes it's not noticeable.
> 3. Sometimes it seems that leaning the mixture helps a bit but not
> always
> 4. I've also noticed that sometimes when the problem has occured on a
> flight that on shutdown of the engine after landing, it doesn't
want
> to
> stop running with the mixture pulled all the way to lean/idle-cutoff.
> 5. Sometimes I the lean the mixture during the 1500 RPM ground check
> and the RPM goes up 50 RPM or so, sometimes it doesn't
> 6. Once I level off the problem seems to disappear or be almost
> un-noticeable. Although tonight I applied full rich mixture while in
> level
> flight at 4,500' and I could notice a slight RPM fluctuation if I
> paid close
> attention.
> 7. Fuel pressure is normal and turning the fuel pump on or off has no
> affect on the engine
>
> My thoughts:
>
> 1. I think the problem is in some fuel metering mechanism in the
> carburetor that is unsteady
> 2. At one point I thought there might be a leak in the turbo pressure
> lines causing a fluctuation in turbo air to the engine
> 3. Now, with the engine shut down problem (doesn't happen every time)
> I think there is a link between the turbo air (as I bring it up on
> climb)
> and fuel metering. They are probably interrelated.
>
> I've received help from many of you out there before. Has anyone had
this
> type problem occur and if so what might be the problem?
>
> Thank you,
>
> Ray Mansfield
> N91ES
> 850-217-5185
>
>
>
>
>
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| Subject: | AC-680 FLP Engine RPM Fluctuation |
I am not sure that I remember the Orenda story correctly, Don, but folks on
this list know a lot more about it than I do. Apparently it ran out of money
and / or there wasn't enough push in Canada at the time to complete the job
to certification. Perhaps someone could enlighten us, but it is a topic that
has been discussed until there was a grove in the ground. :-)
Nico
_____
From: owner-commander-list-server@matronics.com
[mailto:owner-commander-list-server@matronics.com] On Behalf Of Don Barry
Home
Sent: Tuesday, October 28, 2008 9:00 PM
Subject: RE: Commander-List: AC-680 FLP Engine RPM Fluctuation
MR. RPM is out of business?? I wonder whatever happened to that AC they were
playing around with the water-cooled Orenda engines.
Don
Houston TX
_____
From: owner-commander-list-server@matronics.com
[mailto:owner-commander-list-server@matronics.com] On Behalf Of Tom Fisher
Sent: Tuesday, October 28, 2008 10:46 PM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
I do not yet have engine monitors but they are on the wish list.
Well he was out of the business and already sold the STC and as far as I was
concerned I was happy to receive the lines from him even if they had to be
tweaked by an expensive AME who did in fact anneal the welds, good point.
Tom.
C-GISS
----- Original Message -----
From: willis robison <mailto:drwer2@yahoo.com>
Sent: Tuesday, October 28, 2008 8:11 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, Next time you fly, once youve leaned for cruise, check the EGTs for
those cylilnders that had the new lines welded. If they are running within
a few degrees of the others, then he did a good job welding. SS lines with
anything less than 130 thou. diam are extremely hard to weld without causing
an "orifice" at the weldsite.
Also, I doubt that he annealed the new weld, which will make the heat
affected zone more brittle than the rest. Ask him how he treated the weld.
(a smoky acetylene torch for 2 minutes would be sufficient.
Bottom line, Mr.RPM should have is axxx chewed for sending you lousy parts.
You shouldnt have to do his Acceptance test procedures on your AC.
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Well, I am that much more informed, thanks for the info.
Tom
C-GISS
----- Original Message -----
From: willis robison <mailto:drwer2@yahoo.com>
Sent: Monday, October 27, 2008 11:54 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Thanks Tom.
Ive designed a few fuel systems and his symptoms are typical of a
flowdivider/lines on the hot side of an engine. (side downstream of an air
cooled engine) And are more prevalent with Lines that have a lot of volume.
Im unfamiliar with Commanders, but from the looks of the cowl inlets on some
of them, it appears the cooling airflow is from bottom to top and then out.
If not then there is a big air-dam that deflects cool air to the top of the
engine and then down. Either way, cooling appears greatly reduced during
climbout unless there are some big cown-vents downstream.
As Ive seen it.
1. larger dia. lines have a higher vapor/liquid ratio during operation, and
on shut down, cook-off the remaining fuel in the FDV. they are better,
however on climbout as there is less pressure losses and heat absorbed.
Modern FDV's have a purge valve that dumps fuel back to the inlet of the
pump on shutdown. this immediately drops the pressure at the nozzles to
zero...
2. smaller lines have shorter fill times, quicker starts but are susceptible
to vapor lock because they absorb heat faster. At higher flowrates (rich)
the delta-P loss in these lines may result in a higher vapor/liquid rato
and thus a poorer spray patter at the nozzle. This is more of an issue on
climbout on engines with poor cooling for whatever reason (like closed
cowlvents, or just reduced airspeed (airflow)). Modern fuellines in these
situations are insulated (just like grandpas truck).
3. for systems with high flowrates (~100 pph or more) the different lengths
of fuel lines from the FDV to each nozzle becomes important. there are
different pressure losses in each leg. (which makes GAMI's all the more
important. ) If you want to save yourself the recurring cost of Gami
injectors...get your flow divider valve balanced with your set of nozzles.
Just some thoughts.
wer
former Pratt-Whitney and Ham-STD
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
I got a new set from Mr.RPM himself so I assume they were of the same inside
diameter and yes his lines leaked and had to be welded in two places. I just
replaced the lines from the flow divider to the cylinders.
Tom.
C-GISS
----- Original Message -----
From: willis robison <mailto:drwer2@yahoo.com>
Sent: Monday, October 27, 2008 7:59 AM
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
Tom, did you replace the lines with ones of the same Inside diameter? Did
you replace those on both sides of the flow divider (spider), and the fuel
servo?
wer
--- On Mon, 10/27/08, Tom Fisher <tfisher@commandergroup.bc.ca> wrote:
From: Tom Fisher <tfisher@commandergroup.bc.ca>
Subject: Re: Commander-List: AC-680 FLP Engine RPM Fluctuation
<tfisher@commandergroup.bc.ca>
I had the same surging problem on mine.
I replaced all the upper deck lines with new stainless steel lines, the new
lines also had to be welded in two places, this resolved the surging
problem.
Tom
C-GISS
680FLP (Mr.RPM)
----- Original Message -----
From: "Ray Mansfeld" <hcourier@cox.net>
Sent: Sunday, October 26, 2008 6:14 PM
Subject: Commander-List: AC-680 FLP Engine RPM Fluctuation
<hcourier@cox.net>
>
> Am having a problem with the left engine on the 680 FLP I fly (Mr. RPM
> Conversion). Takeoff is fine but on climb out the left engine RPM is
> unsteady, somewhat like a prop that won't stabilize. Here's some
info:
>
> 1. The problem seems to occur primarily during climb as I bring the
> turbos up (I've got manual turbos)
> 2. The fluctuation is random as to when it occurs and how much the RPM
> fluctuates...probably 10-20 RPM. Sometimes it's noticeable as
the
> aircraft yaws, sometimes it's not noticeable.
> 3. Sometimes it seems that leaning the mixture helps a bit but not
> always
> 4. I've also noticed that sometimes when the problem has occured on a
> flight that on shutdown of the engine after landing, it doesn't
want
> to
> stop running with the mixture pulled all the way to lean/idle-cutoff.
> 5. Sometimes I the lean the mixture during the 1500 RPM ground check
> and the RPM goes up 50 RPM or so, sometimes it doesn't
> 6. Once I level off the problem seems to disappear or be almost
> un-noticeable. Although tonight I applied full rich mixture while in
> level
> flight at 4,500' and I could notice a slight RPM fluctuation if I
> paid close
> attention.
> 7. Fuel pressure is normal and turning the fuel pump on or off has no
> affect on the engine
>
> My thoughts:
>
> 1. I think the problem is in some fuel metering mechanism in the
> carburetor that is unsteady
> 2. At one point I thought there might be a leak in the turbo pressure
> lines causing a fluctuation in turbo air to the engine
> 3. Now, with the engine shut down problem (doesn't happen every time)
> I think there is a link between the turbo air (as I bring it up on
> climb)
> and fuel metering. They are probably interrelated.
>
> I've received help from many of you out there before. Has anyone had
this
> type problem occur and if so what might be the problem?
>
> Thank you,
>
> Ray Mansfield
> N91ES
> 850-217-5185
>
>
>
>
>
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