B: Fuel sending units and gauges
James Averett
flyinga at dishmail.net
Fri Jan 25 18:05:08 EST 2008
Hi John,
D5670. It's a simple circuit. I don't believe it's my fuel sending units
because (with all tanks full) both gages (main and aux) read the same when the
gage selector switch is switched; i.e. If the left main shows 3/8 (fairly
common) the right main also shows the same. The aux gage, if left is selected,
may show 1/4 and the right aux will be the same. As fuel is used the proper
gage does go down proportionally. E is empty on the mains, but the aux gages go
below E before they are dry.
If the sending units (floats) work by increasing resistance as the float goes
down, than any increased resistance accumulated in the wiring, CB, selector
switch or connections will cause the gage to read low. Right? Do you have any
idea what the resistance values at the extremes of travel in the sending unit
should be? Is there any adjustment capability in the system (I can't find any)?
Thanks,
Jim Averett
J35 IO550
TS36
Texas Hill Country
-----Original Message-----
From: beech-owners-bounces at beechcraft.org
[mailto:beech-owners-bounces at beechcraft.org] On Behalf Of John Collins
Sent: Friday, January 25, 2008 4:12 PM
To: beech-owners at beechcraft.org
Subject: Re: B: Fuel sending units and gauges
There are so so many different arrangements on fuel gauges, that I no longer
comment on this question if the questioner doesn't provide a serial number.
Some are adjustable, some not. Some use a bridge circuit, some don't. Some
have a PCB, others don't. So often, the experience on one aircraft does not
translate into good advise on another. I checked and there are 22 different
circuits on the various 35 models alone, without mentioning the 33, 36, 55,
56, and 58 models.
So if you are interested in my comments, give me a serial number.
Regards,
John D. Collins
4317 Old Saybrook Ct
Charlotte, NC 28211
(704) 365-1161 Home
(704) 576-3561 Cell
68 V35A N7083N, KUZA
----- Original Message -----
From: "Cy Galley" <cgalley at mchsi.com>
To: <beech-owners at beechcraft.org>
Sent: Friday, January 25, 2008 3:36 PM
Subject: Re: B: Fuel sending units and gauges
> No, an open ground should make it read empty.
>
>
> ----- Original Message -----
> From: "Brandon Mercade" <bonanza365b at gmail.com>
> To: <beech-owners at beechcraft.org>
> Sent: Friday, January 25, 2008 11:54 AM
> Subject: Re: B: Fuel sending units and gauges
>
>
>> Mike- Mine are very accurate but seem to hit empty with about 3 gal left.
>> This is as it sould be because those last 3 gal. are my freebees. I do
>> have
>> an issue with the aux tanks sometimes reading beyond full. This seems
>> like
>> it could be an open ground- does this sound right to you?
>>
>> Brandon
>>
>> On Jan 25, 2008 9:01 AM, <N5522F at cfl.rr.com> wrote:
>>
>>> Hi, Jim --
>>>
>>> I've got an H35 with auxes, and all four senders use a single gauge.
>>>
>>> The gauge is accurate over its full range with *none* of the tanks, and
>>> the inaccuracy is different from one tank to the next. (Eg., when one
>>> tank
>>> is full, the gauge reads 3/4 full. But when another is full, it might
>>> read
>>> 1/2 full, etc.) The gauge itself *does* display over its entire range of
>>> needle movement.
>>>
>>> A few months ago I checked and cleaned the connections at the sending
>>> units of the main tanks. (By removing the plate on top of the wing next
>>> to
>>> the filler port.) I paid particular attention to the little ground strap
>>> there.
>>>
>>> It's not a difficult task, but it takes some time and involves some
>>> safety-wiring, etc.
>>>
>>> Unfortunately, my efforts didn't seem to change a thing. I didn't do the
>>> auxes because my lack of success with the mains.
>>>
>>> My next attempt will involve checking the range of motion of the senders
>>> (the floats) and seeing how the gauge reacts to each. (Is it at the top
>>> of
>>> its travel when the tank is full? If so, what does the gauge say?)
>>>
>>> Anyway, if you have any luck fixing yours, I'd love to hear the details.
>>>
>>> Thanks.
>>>
>>> --Mike Truffer
>>> H35
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: James Averett
>>> To: beech-owners at beechcraft.org
>>> Sent: Friday, January 25, 2008 11:33 AM
>>> Subject: B: RE: Re: Fuel sending units and gauges
>>>
>>>
>>> Bob,
>>>
>>> I have the same problem that Larry does. I'm quite certain that it is
>>> just
>>> minor resistance increases at connections, switches and circuit
>>> breakers
>>> over
>>> the years. I tried jumping the CB to see if that was the cause, but
>>> there was
>>> no change.
>>>
>>> Where are the connections that can be checked? In my plane it seems
>>> that
>>> both
>>> the aux and main gages are either closer to correct or very wrong at
>>> the
>>> same
>>> time. Is there a common ground or other common connection that is the
>>> likely
>>> culprit? I imagine my J is like your H; do you have any other
>>> suggestions?
>>>
>>> Thank goodness for the FS 450!
>>>
>>> Thanks,
>>>
>>> Jim Averett
>>> J35 IO550
>>> TS36
>>> Texas Hill Country
>>>
>>> -----Original Message-----
>>> From: beech-owners-bounces at beechcraft.org
>>> [mailto:beech-owners-bounces at beechcraft.org] On Behalf Of Bob Butt
>>> Sent: Friday, January 25, 2008 9:44 AM
>>> To: beech-owners at beechcraft.org
>>> Subject: B: Re: Fuel sending units and gauges
>>>
>>> Larry,
>>> The OEM system is reasonably accurate when all is working right. Check
>>> connections and the moving parts first. There are some resistance
>>> readings ?
>>> to tell if the senders are functionally correct. The gages in our bird
>>> represent a fairly representative quantity of the real fuel levels in
>>> our
>>> small but numerous tanks.
>>>
>>> BB:
>>> H-35
>>>
>>> ----- Original Message -----
>>> From: "Larry Gaines" <lcg at inreach.com>
>>> To: <beech-owners at beechcraft.org>
>>> Sent: Friday, January 25, 2008 3:49 AM
>>> Subject: B: Fuel sending units and gauges
>>>
>>>
>>> > Speaking of fuel senders, does anyone make more modern, more accurate
>>> > senders for our tanks? All 4 of my gauges read empty when they are
>>> empty,
>>> > but that's about the only time they are anywhere near accurate. They
>>> meet
>>> > the regulatory requirement, but they are not much help in the "real
>>> world".
>>> >
>>> > I know cars and airplanes don't compare, but the automotive world has
>>> come
>>> a
>>> > long way in this area. Has any of that "technology" made it our way,
>>> yet?
>>> > Do the experimental guys live in a better world in this respect, too?
>>> >
>>> > Mike, is there a CSOB solution to this problem?
>>> >
>>> > Larry
>>> >
>>> >
>>> > ----- Original Message -----
>>> > From: "Scott Leonard" <scottleonard at wi.rr.com>
>>> > To: <beech-owners at beechcraft.org>
>>> > Sent: Friday, January 25, 2008 2:42 AM
>>> > Subject: Re: B: fuel venting issue
>>> >
>>> >
>>> > > The previous owner of my airplane liked to wax it a lot, and pushed
>>> > > wax into the vent hole without realizing it.
>>> > >
>>> > > On a trip I noticed that the fuel gauge started increasing in level
>>> on
>>> one
>>> > > tank. I thought it was a bad sender
>>> > > but when I arrived and opened the gas cap the bottom of the fuel
>>> bladder
>>> > > was touching the filler opening and
>>> > > a rush of air came in and the tank dropped back down.
>>> > >
>>> > > Since then I have pointed out that vent to a few people and have
>>> found
>>> > > that most do not realize that it is there.
>>> > >
>>> > >
>>> > > Scot Leonard
>>> > > P35
>>> > > KUES
>>> > >
>>> > > ----- Original Message -----
>>> > > From: "Tom Rosen" <tsrosen at pacbell.net>
>>> > > To: <beech-owners at beechcraft.org>
>>> > > Sent: Thursday, January 24, 2008 8:13 PM
>>> > > Subject: Re: B: fuel venting issue
>>> > >
>>> > >
>>> > >> Bill,
>>> > >> I once cleaned a mud dauber out of that siphon break line you
>>> refer
>>> to
>>> > >> that was up past the ninety degree elbow right against the check
>>> valve.
>>> > >> A drill couldn't get to it. Had to open the access panel and
>>> remove
>>> the
>>> > >> line and valve. Twenty minute job and problem solved. I couldn't
>>> > >> believe how far up the line that little wasp went to build the
>>> nest.
>>> > >> Tom Rosen S35
>>> > >> Woodland, CA
>>> > >>
>>> > >> Bill Hale <33bonanza at gmail.com> wrote:
>>> > >> They don't call it a "Syphon Break" for nothing. First step would
>>> be
>>> to
>>> > >> check
>>> > >> the line, which is the hole in the bottom of the wing near the
>>> tiedown
>>> > >> ring.
>>> > >> Take about a 1/8" drill and turn it in you fingers as you press it
>>> up
>>> > >> into
>>> > >> the hole.
>>> > >>
>>> > >> The valve could also fail but that's much less likely.
>>> > >>
>>> > >> Bill H.
>>> > >>
>>> > >>
>>> > >> On 1/23/08, Ed Livermore wrote:
>>> > >>>
>>> > >>> About 10 days ago, while on a trip to California, the FBO called
>>> me
>>> to
>>> > >>> report that fuel was venting my left wing tip. They had already
>>> removed
>>> > >>> the
>>> > >>> cap which equalized pressure and the venting stopped...but not
>>> before
>>> 3
>>> > >>> or
>>> > >>> 4
>>> > >>> gallons had escaped. I thought, "we overfilled that one."
>>> > >>>
>>> > >>> Today, as I reported in a previous email, we went to the airport
>>> here
>>> in
>>> > >>> Kerrville for our now aborted flight to Phoenix and found the
>>> left
>>> tank
>>> > >>> down
>>> > >>> again...this time 10 gallons. The line guys told me they observed
>>> the
>>> > >>> venting, removed the cap, heard a "whoosh" of pressure equalizing
>>> and
>>> > >>> the
>>> > >>> venting stopped. They reported the venting fuel was coming from
>>> the
>>> tube
>>> > >>> at
>>> > >>> the right rear of the left wing, near the fuselage.
>>> > >>>
>>> > >>> I don't know what's going on here. What would make a main fuel
>>> tank
>>> do
>>> > >>> that?
>>> > >>> What is the fix?
>>> > >>>
>>> > >>> By the way, the tip tanks were empty in both instances.
>>> > >>>
>>> > >>>
>>> > >>>
>>> > >>> No virus found in this outgoing message.
>>> > >>> Checked by AVG Free Edition.
>>> > >>> Version: 7.5.516 / Virus Database: 269.19.9/1239 - Release Date:
>>> > >>> 1/23/2008
>>> > >>> 10:24 AM
>>> > >>>
>>> > >>>
>>> > >>>
>>> > >>
>>> > >>
>>> > >
>>> > >
>>> > >
>>> >
>>> >
>>> >
>>> >
>>> > __________ NOD32 2822 (20080125) Information __________
>>> >
>>> > This message was checked by NOD32 antivirus system.
>>> > http://www.eset.com
>>> >
>>> >
>>>
>>>
>>> No virus found in this incoming message.
>>> Checked by AVG Free Edition.
>>> Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date:
>>> 1/25/2008
>>> 11:24 AM
>>>
>>>
>>> No virus found in this outgoing message.
>>> Checked by AVG Free Edition.
>>> Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date:
>>> 1/25/2008
>>> 11:24 AM
>>>
>>>
>>>
>>
>>
>> --
>> Brandon
>> 1957 H35 Bonanza
>> IO-520BA Conversion
>> N365B Serial# D-4995
>>
>
>
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.11/1243 - Release Date: 1/25/2008
11:24 AM
No virus found in this outgoing message.
Checked by AVG Free Edition.
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