Today's Message Index:
----------------------
0. 12:09 AM - What Are You Thankful For...? (Matt Dralle)
1. 02:54 AM - Re: High indicated fuel flow with fuel pump on (James, Clive R)
2. 04:05 AM - Re: High indicated fuel flow with fuel pump on (Tex Mantell)
3. 04:11 AM - Re: High indicated fuel flow with fuel pump on (IFLYSMODEL@AOL.COM)
4. 05:46 AM - Re: High indicated fuel flow with fuel pump on (Kayberg@aol.com)
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| Subject: | What Are You Thankful For...? |
Dear Listers,
Here in the United States, Thursday is our National day of Thanksgiving. Many
of us will be traveling to be with our families and friends to share in generous
feasts of plenty and giving thanks for many blessings that have been bestowed
upon us.
Many Listers have expressed over the last couple of weeks how thankful they are
for the Email Lists and Forums here on the Matronics servers and for all of the
assistance and comradery they have experienced being a part of the Lists.
One of my favorite comments is when someone writes to me and says something like,
"Its the first thing I do in the morning while I'm having my morning coffee!".
That's a wonderful tribute to the purpose and function of these Lists.
Its always great to hear I'm not the only one that jumps out of bed each morning
to check my List email!!
Won't you take a minute today and show your appreciation for these Lists and for
their continued operation and upgrade?
The List Contribution Site is:
http://www.matronics.com/contribution
Thank you in advance for your kind consideration,
Matt Dralle
Matronics Email List Administrator
Message 1
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| Subject: | High indicated fuel flow with fuel pump on |
The fuel flow meter picks up the pulse of pressure from the pump which
you've no doubt gathered.
This is what I've seen on several jabs with fuel flow meters, yet
another application where knowing too much causes questions that the old
simple applications wouldn't have brought up!
I did wonder if there was a sensor that wouldn't do this, maybe an
ultrasonic one but I imagine those are either not made yet or too
expensive.
CJ
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bill
Strahan
Sent: 26 November 2009 02:06
Subject: Lightning-List: High indicated fuel flow with fuel pump on
I've been fleshing out my checklist and recently decided to add turning
the fuel pump on for takeoff and landing. I'm used to that with my
Grumman, and it felt natural to do it that way.
Today I took off using the new checklist, and once I was a few miles
from the airport I noticed my fuel flow was 11GPH! I've never seen
anything near that high and my fuel flow already was reading about 10%
too high.
I throttled back to a setting that typically shows 4.5-5 gph and was
seeing 7. For a moment, I pictured a fuel leak and decided to turn the
boost pump on and see if the fuel flow surged, which would confirm a
leak on the firewall side, and I was going to immediately return to the
airport.
Instead I realized I had left the boost pump on since takeoff and then I
wondered if that was the cause of the high reading. Sure enough, with
the boost pump off the EIS indicated 5.1 gph. Boost pump on and it
jumped back to 7 or so.
I was pretty sure I didn't have a fuel leak at that point, so left the
pump on for a half hour or so while I flew. I saw a growing disparity
between what the totalizer thought I had left and what the tanks were
indicating, confirming to me that the indication is all that was
changing, I wasn't pumping fuel overboard.
So, anyone else noticed the same thing? I would have thought the flow
sensor would have been independent of fuel pressure, but that appears to
not be the case.
Bill
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=274827#274827
Message 2
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| Subject: | Re: High indicated fuel flow with fuel pump on |
Bill , I have seen bthe same thing and have not figured out what causes it.
There is no leak. Tex
--- Original Message -----
From: "Bill Strahan" <bill@gdsx.com>
Sent: Wednesday, November 25, 2009 9:06 PM
Subject: Lightning-List: High indicated fuel flow with fuel pump on
>
> I've been fleshing out my checklist and recently decided to add turning
> the fuel pump on for takeoff and landing. I'm used to that with my
> Grumman, and it felt natural to do it that way.
>
> Today I took off using the new checklist, and once I was a few miles from
> the airport I noticed my fuel flow was 11GPH! I've never seen anything
> near that high and my fuel flow already was reading about 10% too high.
>
> I throttled back to a setting that typically shows 4.5-5 gph and was
> seeing 7. For a moment, I pictured a fuel leak and decided to turn the
> boost pump on and see if the fuel flow surged, which would confirm a leak
> on the firewall side, and I was going to immediately return to the
> airport.
>
> Instead I realized I had left the boost pump on since takeoff and then I
> wondered if that was the cause of the high reading. Sure enough, with the
> boost pump off the EIS indicated 5.1 gph. Boost pump on and it jumped
> back to 7 or so.
>
> I was pretty sure I didn't have a fuel leak at that point, so left the
> pump on for a half hour or so while I flew. I saw a growing disparity
> between what the totalizer thought I had left and what the tanks were
> indicating, confirming to me that the indication is all that was changing,
> I wasn't pumping fuel overboard.
>
> So, anyone else noticed the same thing? I would have thought the flow
> sensor would have been independent of fuel pressure, but that appears to
> not be the case.
>
> Bill
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=274827#274827
>
>
>
Message 3
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| Subject: | Re: High indicated fuel flow with fuel pump on |
Me Too.
Lynn Nelsen
In a message dated 11/26/2009 7:06:09 A.M. Eastern Standard Time,
wb2ssj@frontiernet.net writes:
--> Lightning-List message posted by: "Tex Mantell"
<wb2ssj@frontiernet.net>
Bill , I have seen bthe same thing and have not figured out what causes
it.
There is no leak. Tex
--- Original Message -----
From: "Bill Strahan" <bill@gdsx.com>
Sent: Wednesday, November 25, 2009 9:06 PM
Subject: Lightning-List: High indicated fuel flow with fuel pump on
> --> Lightning-List message posted by: "Bill Strahan" <bill@gdsx.com>
>
> I've been fleshing out my checklist and recently decided to add turning
> the fuel pump on for takeoff and landing. I'm used to that with my
> Grumman, and it felt natural to do it that way.
>
> Today I took off using the new checklist, and once I was a few miles
from
> the airport I noticed my fuel flow was 11GPH! I've never seen anything
> near that high and my fuel flow already was reading about 10% too high.
>
> I throttled back to a setting that typically shows 4.5-5 gph and was
> seeing 7. For a moment, I pictured a fuel leak and decided to turn the
> boost pump on and see if the fuel flow surged, which would confirm a
leak
> on the firewall side, and I was going to immediately return to the
> airport.
>
> Instead I realized I had left the boost pump on since takeoff and then I
> wondered if that was the cause of the high reading. Sure enough, with
the
> boost pump off the EIS indicated 5.1 gph. Boost pump on and it jumped
> back to 7 or so.
>
> I was pretty sure I didn't have a fuel leak at that point, so left the
> pump on for a half hour or so while I flew. I saw a growing disparity
> between what the totalizer thought I had left and what the tanks were
> indicating, confirming to me that the indication is all that was
changing,
> I wasn't pumping fuel overboard.
>
> So, anyone else noticed the same thing? I would have thought the flow
> sensor would have been independent of fuel pressure, but that appears to
> not be the case.
>
> Bill
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=274827#274827
>
>
>
Message 4
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| Subject: | Re: High indicated fuel flow with fuel pump on |
In a message dated 11/25/2009 9:06:51 P.M. Eastern Standard Time,
bill@gdsx.com writes:
I've been fleshing out my checklist and recently decided to add turning
the fuel pump on for takeoff and landing. I'm used to that with my Grumman,
and it felt natural to do it that way.
I want to offer an alternitive thought about when to use the electric fuel
pump.
I use the electric to be sure the carb is full before starting. Then I
turn it off.... I turn it back on briefly during runup before takeoff to
insure the engine runs with both on.
My emergency procedures for a loss of power call for 1) electric fuel
pump on 2) switch tanks.
If you lose power on takeoff with both pumps running, you dont know what
went wrong. If the power is restored with the electric pump on, it is
likely the mechanical one failed. If it failed it could be pumping fuel out
somewhere and you will want to land immediatly.
If you happened to run a tank dry or had it unport because of low fuel in a
down wing, you will want to be sure the pump is on, so just assuming it
was on for takeoff ( notice how often we forget to turn it on?) may not be
the best. Hence, always: Hit electric pump switch and switch tanks. It
takes about a 5 count for the engine to pick up on an empty tank switch.
Dont ask me how I know!
Switching tanks is a must because the fuel filter could have clogged on the
one being fed...or the fuel guages are wrong. Of course if the other
tank is dry or too low to reliably feed, shame on you!! I would suggest you
never take off with either tank that is too low to feed on a takeoff.
Just my thoughts on use of the boost pump.
Now, The Facet pump has a built in check valve. I suspect the engine
driven pump has a higher pressure than the Facet we commonly use. When the
facet is on, the check valve is fluttering. I suspect the higher presure
from the engine driven is pushing some fuel past the check valve. Even a
very little bit will show up on the fuel flow.
FWIW
Doug Koenigsberg
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