An animal so rare it may not exist . . .

[[email protected]]

Folks:

I have a rather irritating fuel line situation that has several
possible solutions, each more complicated and / or expensive than the
last. Specifically I need a remotely mounted fuel cutoff valve, but it
is so remotely mounted that the standard valve-on-a-long-ujoint
solution is not going to work (too much stuff in the way, too many
corners, etc.).

In discussing this with the local EAA guys, the tech counselors, and
even talking to the local FAA, they all look at the problem and
eventually say, "you know what you need is a solenoid."

Ok. My reply to them is that I understood that solenoid valves for
fuel control were deeply frowned upon unless you are Boeing. I am not
Boeing. Part of my understanding as to why solenoids are not a good
thing is that they will obviously have a fail-open or fail-closed
failure mode, either of which can be deadly depending on the nature of
a given situation.

However the local FAA guy told me that he has seen solenoid valves made
specifically for fuel applications that fail in place, i.e. if they
crap out the valve simply stays in it's last selected position.

I can't find one. Partly this is because I don't know what they might
be called, but I have tried everything I can think of, including
calling some of the larger solenoid valve manufacturers to see what
they might suggest. If anyone has any insight into this, it is most
appreciated.

Thank you for your assistance--

Steve.

PS: I have also seen electrically actuated rotary valves, which appear
to simply be a fairly traditional selector valve actuated by a stepper
motor. They fail in place, which is good. But in doing some research,
they appear to have a much lower MTBF than a solenoid.

[[email protected]]

wrote:
> Folks:
>
> I have a rather irritating fuel line situation that has several
> possible solutions, each more complicated and / or expensive than the
> last. Specifically I need a remotely mounted fuel cutoff valve, but it
> is so remotely mounted that the standard valve-on-a-long-ujoint
> solution is not going to work (too much stuff in the way, too many
> corners, etc.).
>
> In discussing this with the local EAA guys, the tech counselors, and
> even talking to the local FAA, they all look at the problem and
> eventually say, "you know what you need is a solenoid."
>
> Ok. My reply to them is that I understood that solenoid valves for
> fuel control were deeply frowned upon unless you are Boeing. I am not
> Boeing. Part of my understanding as to why solenoids are not a good
> thing is that they will obviously have a fail-open or fail-closed
> failure mode, either of which can be deadly depending on the nature of
> a given situation.
>
> However the local FAA guy told me that he has seen solenoid valves made
> specifically for fuel applications that fail in place, i.e. if they
> crap out the valve simply stays in it's last selected position.
>
> I can't find one. Partly this is because I don't know what they might
> be called, but I have tried everything I can think of, including
> calling some of the larger solenoid valve manufacturers to see what
> they might suggest. If anyone has any insight into this, it is most
> appreciated.
>
> Thank you for your assistance--
>
> Steve.
>
> PS: I have also seen electrically actuated rotary valves, which appear
> to simply be a fairly traditional selector valve actuated by a stepper
> motor. They fail in place, which is good. But in doing some research,
> they appear to have a much lower MTBF than a solenoid.

Solenoid valves might be OK for an airplane that has backup
electrical systems, but in the average lightplane with a single system
you might find yourself unable to shut the fuel off in the event of an
emergency that requires shutdown of the electrical system.
I'd adapt an ordinary ball valve lever to operate using a
push-pull cable, even if the heavier PTO cable was necessary. It would
still be simpler, lighter and more reliable. You could even use a pair
of 1/16" control cables and a pulley or sector on the valve, but if
corners must be negotiated you'd need more pulleys, adding complexity
and weight.

Dan

[Capt. Geoffrey Thorpe]

> wrote in message
ups.com...
> Folks:
>
> I have a rather irritating fuel line situation that has several
> possible solutions, each more complicated and / or expensive than the
> last. Specifically I need a remotely mounted fuel cutoff valve, but it
> is so remotely mounted that the standard valve-on-a-long-ujoint
> solution is not going to work (too much stuff in the way, too many
> corners, etc.).
>
> In discussing this with the local EAA guys, the tech counselors, and
> even talking to the local FAA, they all look at the problem and
> eventually say, "you know what you need is a solenoid."
>
> Ok. My reply to them is that I understood that solenoid valves for
> fuel control were deeply frowned upon unless you are Boeing. I am not
> Boeing. Part of my understanding as to why solenoids are not a good
> thing is that they will obviously have a fail-open or fail-closed
> failure mode, either of which can be deadly depending on the nature of
> a given situation.
>
> However the local FAA guy told me that he has seen solenoid valves made
> specifically for fuel applications that fail in place, i.e. if they
> crap out the valve simply stays in it's last selected position.
>
<.snippage..>

Something like this?

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2005712/p-2005712/N-111+10201+600002072/c-10101

(cap the unused inlet)

???

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[jmk]

wrote:
> I have a rather irritating fuel line situation that has several
> possible solutions, each more complicated and / or expensive than the
> last. Specifically I need a remotely mounted fuel cutoff valve, but it
> is so remotely mounted that the standard valve-on-a-long-ujoint
> solution is not going to work (too much stuff in the way, too many
> corners, etc.).
> However the local FAA guy told me that he has seen solenoid valves made
> specifically for fuel applications that fail in place, i.e. if they
> crap out the valve simply stays in it's last selected position.

If it is a simple fuel shutoff issue, then just mount the appropriate
valve for which ever you consider (or your FAA guy considers) less
critical. That is, normally open or normally closed. Loss of
electrical system reverts it to the "normal" position.

The only other real failure mode is that it sticks... and hey, it stays
in its last position.

Depends on what you consider most critical... if this is a "fuel tank
selector" thing you are trying to create, then two of them - mounted
NO, and held closed by the electrical system. Mount a mechanical 90
degree cutoff valve somewhere for those times when you want to work on
things on the ground. In flight you have a left-selected, or
right-selected, or (lose your electrical system) both.

Yes, these things do fail... but not NEAR as often as the standard
Piper in-cockpit mechanical fuel tank selector.

[[email protected]]

jmk wrote:

>
> If it is a simple fuel shutoff issue, then just mount the appropriate
> valve for which ever you consider (or your FAA guy considers) less
> critical. That is, normally open or normally closed. Loss of
> electrical system reverts it to the "normal" position.

I doubt that they'll approve it. Too dependednt on the system
one way or another. If you had a fuel leak in flight that resulted in
an engine compartment fire, you'd need to shut everything down, fuel
and electrical, in order to have any decent chance of making a
survivable forced landing, and you wouldn't be able to shut the fuel
off. If you left the elecrical on, the fire would shut it off for you.

> The only other real failure mode is that it sticks... and hey, it stays
> in its last position.
>
> Depends on what you consider most critical... if this is a "fuel tank
> selector" thing you are trying to create, then two of them - mounted
> NO, and held closed by the electrical system. Mount a mechanical 90
> degree cutoff valve somewhere for those times when you want to work on
> things on the ground. In flight you have a left-selected, or
> right-selected, or (lose your electrical system) both.
>
If it's a low-wing airplane, you don't want a BOTH position. If
one tank runs dry before the other, the pump will happily suck air from
the dry tank instead of fuel from the one with fuel. FAR 23.951
addresses this issue in certified airplanes.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/BF16A7A7B336B60D85256687007074F2?OpenDocument

There are a bunch of FARS that are worth paying attention to when
designing a fuel system. I've been around homebuilding since '73 and
have read too many accident reports involving homebuilt airplanes that
fell down because their builders didn't have the information to alert
them to possible problems.
Fuel tank venting is one of the really big killers. In a
gravity-feed system using two or more tanks fed through a valve that
has a BOTH position or though two valves that may be ON at the same
time, the tanks must be vented together to keep pressures equal lest
uneven fuel flow results. I was involved in a Glastar project, and that
airplane had two wing tanks with separate vents. Uneven fuel flow was a
problem, and if the pressures had been far enough apart the fuel from
the tnak with the lower pressure would have had trouble reaching the
engine once the other tank ran dry. The pressure in the dry line will
keep fuel from dropping through the other line.
The Glastar's vents were also at the wingtips, and if the tanks
were full or nearly full, the fuel would run out of the low vent if the
airplane was the least bit off level. Fuel would crossflow through the
system from the higher tank into the low tank and a lot of fuel ended
up on the floor.
The lesson: copy a certified system.

Dan

[Roger[_4_]]

On 28 Nov 2006 08:18:32 -0800, wrote:

Even with a certified gravity fed system I understand you can get
cross flow. Didn't the 210s have this problem when parked on an
uneven surface?


>
>>
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Morgans[_2_]]

> wrote

> The Glastar's vents were also at the wingtips, and if the tanks
> were full or nearly full, the fuel would run out of the low vent if the
> airplane was the least bit off level. Fuel would crossflow through the
> system from the higher tank into the low tank and a lot of fuel ended
> up on the floor.
> The lesson: copy a certified system.

It always seemed like the best place for a vent on a low wing would be up high
on the fin, with a T to supply both tanks equal pressure. Does anybody know of
a certified vent setup like that?
--
Jim in NC

[[email protected]]

Morgans wrote:
> > wrote
>
> > The Glastar's vents were also at the wingtips, and if the tanks
> > were full or nearly full, the fuel would run out of the low vent if the
> > airplane was the least bit off level. Fuel would crossflow through the
> > system from the higher tank into the low tank and a lot of fuel ended
> > up on the floor.
> > The lesson: copy a certified system.
>
> It always seemed like the best place for a vent on a low wing would be up high
> on the fin, with a T to supply both tanks equal pressure. Does anybody know of
> a certified vent setup like that?
> --
> Jim in NC

In a high nose-up attitude the vent line might fill with fuel,
and the weight of it might act as a drag on the fuel trying to flow
through the outlet lines to the engine. Not good. There are some
systems with a vent at the wing root above the wing, but these tend to
ice up. Cessna sticks them behind the strut to prevent icing. Not that
we should be flying these tiny airplanes in ice, anyway. Cessna just
has to protect themselves from those who try it.
Designing a trouble-free venting system can be a real pain.

Dan

[[email protected]]

Roger wrote:
> On 28 Nov 2006 08:18:32 -0800, wrote:
>
> Even with a certified gravity fed system I understand you can get
> cross flow. Didn't the 210s have this problem when parked on an
> uneven surface?

All the Cessna singles do it, both the simple 150 system that
has a tee between the two lines before the fuel enters the shutoff
valve, and the other systems that use the left-right-both-off selector
valve. They'll crossfeed in the "both" position, which is where most of
them stay most of the time. Placing the selector in the left or right
or off position will stop the crossfeeding. Shutting off a 150's valve
won't stop crossfeed.
The tanks on the Cessnas are vented together to keep pressures
as equal as possible. A cracked fuel cap gasket or broken valve vent
check valve will upset the pressure balance, especially on the right
wing tank, causing the left tank to drain sooner.
Having vents at the tips aggravates the spillage by increasing
the head pressure at the vent opening. Cessna keeps them close to the
tank's outboard wall.

Dan

[Ernest Christley]

wrote:
> Folks:
>
> I have a rather irritating fuel line situation that has several
> possible solutions, each more complicated and / or expensive than the
> last. Specifically I need a remotely mounted fuel cutoff valve, but it
> is so remotely mounted that the standard valve-on-a-long-ujoint
> solution is not going to work (too much stuff in the way, too many
> corners, etc.).
>

Have you considered just putting an electric fuel pump back there. The
pumps I have will block flow when they are turned off.

[Rob Cherney]

On 27 Nov 2006 08:03:15 -0800, wrote:

>Specifically I need a remotely mounted fuel cutoff valve, but it
>is so remotely mounted that the standard valve-on-a-long-ujoint
>solution is not going to work (too much stuff in the way, too many
>corners, etc.).

Andy Phillips, proprietor of Andair, Ltd. in the UK exhibited a
prototype of a remote-mounted, electrically-operated fuel valve at
Oshkosh this year. You could contact him at and
see if it is ready for production. The web site is
http://www.andair.co.uk, if you're interested in looking at his line
of products.

From what I recall, it was operated by a DC motor, not a solenoid.

Rob-
__________________________________________________ _
Rob Cherney rcherney(at)comcast.net
Ellicott City, Maryland

[[email protected]]

wrote:
> Folks:
>
> I have a rather irritating fuel line situation that has several
> possible solutions, each more complicated and / or expensive than the
> last. Specifically I need a remotely mounted fuel cutoff valve, but it
> is so remotely mounted that the standard valve-on-a-long-ujoint
> solution is not going to work (too much stuff in the way, too many
> corners, etc.).

How about cable and pulley system? };-)

>
> ...
>
> However the local FAA guy told me that he has seen solenoid valves made
> specifically for fuel applications that fail in place, i.e. if they
> crap out the valve simply stays in it's last selected position.
>
> I can't find one. Partly this is because I don't know what they might
> be called, but I have tried everything I can think of, including
> calling some of the larger solenoid valve manufacturers to see what
> they might suggest. If anyone has any insight into this, it is most
> appreciated.

If you find somebody who makes a lot of solenoid valves they should
have some like that. I don't remember who does offhand, if you can
find a Thomas Register, that should help.

>
> Thank you for your assistance--
>
> Steve.
>
> PS: I have also seen electrically actuated rotary valves, which appear
> to simply be a fairly traditional selector valve actuated by a stepper
> motor. They fail in place, which is good. But in doing some research,
> they appear to have a much lower MTBF than a solenoid.

Those would be heavier as well as more complicated.
We used them a lot in the nuclear industry, motor actuated
ball valves with UHMWPE seats.

The big advantage over solenoid valves were that they were
less resistant to flow and less prone to leakage.

--

FF