Today's Message Index:
----------------------
1. 03:05 AM - Re: Re: Fuel Flow thru Facet pump (bob noffs)
2. 06:26 AM - Re: Fuel Flow thru Facet pump (mikeperkins)
3. 09:22 AM - Re: Re: Fuel Flow thru Facet pump (Lowell Fitt)
4. 11:02 AM - Re: Re: Fuel Flow thru Facet pump (Michael Kraus)
Message 1
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| Subject: | Re: Fuel Flow thru Facet pump |
as i mentioned in an earlier post some facet models shut off fuel flow when
they are turned off. when i talked to the facet rep he said there is
supposedly a very weak check valve in these that is supposed to open
somewhat. i immediately sent this model [don't remember the model but i got
it from acs] back.
anyone out there with the #40104 like mine that won't flow adequately?
a wing tank must have about 3 psi?
bob noffs
and no one at acs can give you any useable info about these pumps.
On Mon, Sep 2, 2013 at 10:48 PM, clemwehner <clemwehner@sbcglobal.net>wrote:
>
> Lowell,
>
> We wanted to know what best case was with fuel flowing directly out of the
> wing tank, so we hooked a spare hose to the wing tank outlet and routed it
> thru the cockpit along the same path that the normal fuel lines run ending
> at the carb. We tried it with just the hose and then tried it again going
> thru a spare facet pump that we have. We did not involve the header since
> we were looking for best case.
>
> Without the facet pump in the line there was plenty of fuel flow, but with
> the restriction of the facet pump (not running), there wasn't nearly enough
> to meet the test requirements for gravity flow. A lot of guys use facet
> pumps and I wonder if they actually conducted the flow test. I can't see
> how anyone could get the required flow with a facet pump in the line at 25
> degrees attitude, since we couldn't get it at 12 degrees attitude setting
> on the gear.
>
> Fuel will definitely gravity flow through a facet pump, but not nearly at
> the volume that's required. The recent EAA webinar said that 70% of
> homebuilders never actually do the flow test, but just assume that it'll be
> fine since their airplanes are based on existing designs. That's scary.
>
> So we're at the point of doing the test with the actual aircraft's
> plumbing and we know it will be worse than our best case test using just
> the hose and no fittings, valves, etc.
>
> I wonder if any Kitfox builders who have facet pumps have achieved the
> required 150% flow with actual testing. If not, what did they do about it?
> Would a bypass loop around the facet help, or do they just document the
> flow shortfall and make a flight restriction requiring use of the fuel pump
> in takeoff and high power climbs?
>
> thanks for the help,
>
> Clem
> KF-IV, 912
> Oklahoma
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=407958#407958
>
>
Message 2
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| Subject: | Re: Fuel Flow thru Facet pump |
There is a way around needing to meet the gravity-feed minimum-flow requirement
two fuel pumps each capable independently of supply 1.5x max rate in all flight
attitudes.
Think low-wing aircraft - none would pass a gravity-flow test. The FAA just wants
two sources of fuel pressure, each sufficient on their own to operate the engine
at full power in all flight attitudes. So for low-wing aircraft, the minimum
is two fuel pumps or one pump plus a header tank, both of which separately
meet the 1.5x requirement. (Kitfoxes, with their low-mounted header tank, will
usually not meet the 1.5x requirement.)
If your desire is to have two Facet pumps plus the engine-driven fuel pump (three
sources of pressure), one Facet pump could be switched on all the time but
the other could be either on all the time or switched only switched on for TO
and landing. For redundancy, the second pump naturally would be supplied by a
separate switch and breaker. But for the FAA, a single Facet pump would be enough
for their redundancy requirement.
As long as there are at least two independent fuel sources that meet the 1.5x requirement,
it doesnt matter that none of them are gravity-feed.
--------
Mike Perkins
Havana, Illinois
Model I, 532, B gearbox, GSC prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=407972#407972
Message 3
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| Subject: | Re: Fuel Flow thru Facet pump |
This was essentially my take on the discussion on the other forum and what I
gathered from reading the specs from the FAA. I was led to understand
that gravity flow requirements were not dependent on whether the airplane
had high wing tanks conducive to gravity flow, but rather whether the fuel
system had fuel pumps in the system. A Sonex with Rotax 912, would not have
to prove any level of gravity fed fuel flow. We while flying the high wing
Kitfox have a two fold redundancy with an engine driven fuel pump and high
wings providing a level of gravity flow. One poster in the other forum
mentioned that he could maintain altitude with a failed engine driven fuel
pump relying only on gravity fed fuel.
Lowell
--------------------------------------------------
From: "mikeperkins" <flybyewire@gmail.com>
Sent: Tuesday, September 03, 2013 6:25 AM
Subject: Kitfox-List: Re: Fuel Flow thru Facet pump
>
> There is a way around needing to meet the gravity-feed minimum-flow
> requirement ?" two fuel pumps each capable independently of supply 1.5x
> max rate in all flight attitudes.
>
> Think low-wing aircraft - none would pass a gravity-flow test. The FAA
> just wants two sources of fuel pressure, each sufficient on their own to
> operate the engine at full power in all flight attitudes. So for low-wing
> aircraft, the minimum is two fuel pumps or one pump plus a header tank,
> both of which separately meet the 1.5x requirement. (Kitfoxes, with their
> low-mounted header tank, will usually not meet the 1.5x requirement.)
>
> If your desire is to have two Facet pumps plus the engine-driven fuel pump
> (three sources of pressure), one Facet pump could be switched on all the
> time but the other could be either on all the time or switched only
> switched on for TO and landing. For redundancy, the second pump naturally
> would be supplied by a separate switch and breaker. But for the FAA, a
> single Facet pump would be enough for their redundancy requirement.
>
> As long as there are at least two independent fuel sources that meet the
> 1.5x requirement, it doesn?Tt matter that none of them are gravity-feed.
>
> --------
> Mike Perkins
> Havana, Illinois
> Model I, 532, B gearbox, GSC prop
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=407972#407972
>
>
>
Message 4
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| Subject: | Re: Fuel Flow thru Facet pump |
So what is the purpose of the low mounted header tank? Why is the KitFox not designed
with 2 lines (one from each tank) to a selector valve (left-right-both-off)?
Just curious.
-Mike
Sent from my iPhone
On Sep 3, 2013, at 12:21 PM, "Lowell Fitt" <lcfitt@sbcglobal.net> wrote:
> This message cannot be displayed because of the way it is formatted. Ask the
sender to send it again using a different format or email program. text/plain
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