Today's Message Index:
----------------------
1. 05:13 AM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Robert L. Nuckolls, III)
2. 05:35 AM - Re: Re: VHF antenna in the tail (GTH)
3. 05:46 AM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
4. 06:00 AM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
5. 07:00 AM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Earl Schroeder)
6. 07:30 AM - Re: Re: Radio or Television Tower Buzz (Ernest Christley)
7. 08:15 AM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (Eric Page)
8. 09:13 AM - Re: Re: VHF antenna in the tail (Robert L. Nuckolls, III)
9. 09:28 AM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (Eric Page)
10. 10:21 AM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
11. 12:08 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Robert L. Nuckolls, III)
12. 12:15 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Robert L. Nuckolls, III)
13. 02:21 PM - Re: Shower of Sparks (FLYaDIVE)
14. 02:40 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (FLYaDIVE)
15. 02:52 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (Eric Page)
16. 04:43 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
17. 05:09 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (FLYaDIVE)
18. 05:48 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Robert L. Nuckolls, III)
19. 06:09 PM - B&C switches (blues750)
20. 07:18 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
21. 07:26 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (dj_theis)
22. 07:56 PM - Re: Low Battery Voltage Blows Fuel Pump Fuse? (user9253)
23. 08:19 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (FLYaDIVE)
24. 08:27 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (FLYaDIVE)
25. 09:56 PM - Re: B&C switches (Robert L. Nuckolls, III)
26. 10:22 PM - Re: Re: Low Battery Voltage Blows Fuel Pump Fuse? (Robert L. Nuckolls, III)
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
At 09:20 PM 5/21/2018, you wrote:
>
>Bob,
>Thanks for the reply and explanation about how the pump works. I
>had neglected to mention that the fuel pump fuse blows during engine
>cranking. I do not think that makes any difference to the pump,
>other than causing a voltage sag. I measured the current draw of my
>spare pump with an analog Simpson 260. I am as mystified as
>you. Unfortunately the plane is located hundreds of miles
>away. All I have to go by is second hand information.
Yeah . . . been there. I can't begin to tally
the time expended trying to deduce root cause
of a condition based on somebody else's observations
and understanding conveyed by telephone or email.
If we could just put our hands on the thing for
a few minutes, the solution would probably become
clear.
Hmmmm . . . the modern putt-putt pumps do have
solid state exciters for the motor coil . . .
I've been pondering the potential for the
electronics to go into some kind of 'crowbar'
condition during the brownout transient . . .
Here's an exemplar circuit snatched from patent
application 2005/0089418A1:
Emacs!
Good ol' 555 and a FET . . . hard to see how
this might present the symptom . . .
It this a consistent phenomenon . . . pops
fuse every time?
Bob . . .
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Subject: | Re: VHF antenna in the tail |
/Le 20/05/2018 16:26, user9253 a crit:
/
> <fransew@gmail.com> I would try a 1/4 wave antenna with ground plane.
> Of course the small diameter tail is not the ideal shape and size for
> a ground plane. But it might be good enough./
Joe and all,
Thank you to all who responded.
I guess I'll follow your advice and build a mock-up of the "sub-optimal"
ground plane. And then conduct some experiments - for instance calling
aircraft flying nearby etc.
As for other informations, the all moving tailplane is to be carbon
fiber, and the carbon tips are already fabricated.
Interesting info from Jim Weir, but of use for *glass* airplanes. Also
our project has a tiny vertical fin and could not accomodate a 1/2 wave
antenna.
Do not hesitate to keep sending advices !
Will keep you posted,
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
Message 3
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Thanks for that suggestion Stu.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480298#480298
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Bob,
Below are quotes from the original poster:
> Fuel pump fuse blows out at each start
> Hi all, can someone please point me in direction of troubleshooting of at each
start fuel pump fuse blows out, starter feels sluggish in rotating the prop,
battery is sufficiently charged. Thanks in advance.
> (Blows) When key switch is turned to rotate engine at startup.
> Tested battery by advanced auto store and CCA value came out for 33 ( rated 170).
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480299#480299
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Ah, Joe. A Simpson 260.. now that brings back memories. The battery connectors
on my have given up the ghost. I need to design a suitable battery holder replacement.
Any ideas? Thanks for all your informative posts!
> On May 21, 2018, at 9:16 PM, user9253 <fransew@gmail.com> wrote:
>
>
> Bob,
> Thanks for the reply and explanation about how the pump works. I had neglected
to mention that the fuel pump fuse blows during engine cranking. I do not
think that makes any difference to the pump, other than causing a voltage sag.
I measured the current draw of my spare pump with an analog Simpson 260. I
am as mystified as you. Unfortunately the plane is located hundreds of miles
away. All I have to go by is second hand information.
>
> --------
> Joe Gores
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480288#480288
>
>
>
>
>
>
>
>
>
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Subject: | Re: Radio or Television Tower Buzz |
An easy thing to check.=C2- I would get horrible feedback whenever I keye
d my mic.=C2- One day I turned down the volume control on my headset (and
up on the intercom for the same net volume), and the problem went away.
But, it's like Bob said.=C2- You're picking up interference on some part
of the circuit and then it is getting amplified.=C2- The solution is chas
ing down and shielding/attenuating the interference from that ONE spot out
of all the circuits.=C2- Like me, you'll probably find the solution by ac
cident some day.
On Monday, May 21, 2018 11:07 AM, "mike>bentley" <mikeeeb@gmail.com> wr
ote:
com>
Thanks for the input everyone. My plane seems to be the only one this is ha
ppening to as I've flown the same route in everything from Cubs to Challeng
er 300's and no interference. I'll try what you all suggested and report ba
ck.
Thanks again.
--------
Mike Bentley
Joplin, MO
N5498B
Kitfox Model 4-1200
Jabiru 2200=C2- #438
Rotec Aerosport LCH Heads
Prince Prop (64 x 34)
Ellison EFS-2 Throttle Body
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480274#480274
-
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
nuckolls.bob(at)aeroelect wrote:
> I've been pondering the potential for the electronics to go into some kind of
'crowbar' condition during the brownout transient . . .
>
> Here's an exemplar circuit snatched from patent application 2005/0089418A1:
Link to the patent: https://goo.gl/nLh81H
Reading through the patent description, two possibilities, both admittedly remote,
come to mind:
1. TVS diode D4 has seen too much abuse and has failed short. The brief current
spike that results when power is applied is sufficient to blow the fuse but
not to blow D4 clear.
2. MOSFET Q1 has failed short. The patent application says this about the solenoid
coil: In a preferred embodiment, [the] coil is made of 21 gauge magnet wire
and is a 2mH inductor with a resistance of 1.4 ohms. With Q1 shorted, this
would draw >8A at 12V, easily blowing a 5A fuse.
The first failure would probably present as a dead short to a continuity meter
across the pumps supply wires. The second might not register as a short, but
would measure as a very low resistance. Either way, putting a meter across the
pump would prove or debunk my theory.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480306#480306
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Subject: | Re: VHF antenna in the tail |
At 07:33 AM 5/22/2018, you wrote:
>Le 20/05/2018 =C3 16:26, user9253 a =C3=A9crit=C2 :
>>
>>"user9253" <mailto:fransew@gmail.com><fransew@gmail.com>
>>
>>I would try a 1/4 wave antenna with ground
>>plane. Of course the small diameter tail is
>>not the ideal shape and size for a ground plane. But it might be good
enough.
>
>Joe and all,
>
>Thank you to all who responded.
>I guess I'll follow your advice and build a
>mock-up of the "sub-optimal" ground plane. And
>then conduct some experiments - for instance
>calling aircraft flying nearby etc.
the most significant benchmark for performance
will be achieving lowest possible SWR over
the frequencies of interest. As long as the
majority of your radiating conductor is oriented
vertically in the conduit, you're going to
experience adequate performance.
Jim Wier published a study on various factors
influencing line of sight communications about
20 years ago . . . probably got a copy around
here somewhere . . .
The upshot of his piece was the realization
that it takes very little power to communicate
over large distances assuming line of sight
and serviceable antenna efficiencies.
All other things held constant, you'll probably
observe no difference in utility between a
laboratory grade antenna and a relatively
poor DIY product. The tallest and most tractable
hurdles are getting your antenna to accept the
transceiver's power and minimizing lossy (high
resistance) features in the design.
This thread should probably include some exploration
of another option. Some years ago, there was a product
marketed as the "Miracle Air Whip". One of several
reviews can be see here. https://goo.gl/WQyNmu
We had some discussion about the product here on
the List. I published a couple of images . . .
https://goo.gl/ssf7CG
https://goo.gl/upHYTB
Variations on this theme have been proposed and
published in the ham radio venues for decades.
https://goo.gl/zSQpu1
This design will be about 35" long . . . how long
is the conduit extending up the vertical fin?
While rudimentary in the physics of design and performance,
the practical solution needs to select materials
and assembly methods that are suited for the
less than gentle environment of an airplane's
tail cone.
Bob . . .
Message 9
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
For the benefit of those following via email echo, in my previous post, I meant
TVS diode D2, not D4. I've edited my original post on the forum to correct this
error.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480308#480308
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Without seeing your battery holders and exactly what is wrong, it is hard to make
a suggestion. But here is a link to battery holders and parts from Mouser:
https://www.mouser.com/Power/Battery-Holders-Clips-Contacts/_/N-cicxgZ1yzvvqx?P=1z0y6wzZ1yuke34
I have even soldered wires to batteries before using a soldering gun and short
contact time to minimize damage to the cell. I remember that Bob has described
welding wires to dry cells, but I can not remember how he did it.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480313#480313
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
At 10:15 AM 5/22/2018, you wrote:
>
>
>nuckolls.bob(at)aeroelect wrote:
> > I've been pondering the potential for the
> electronics to go into some kind of 'crowbar'
> condition during the brownout transient . . .
> >
> > Here's an exemplar circuit snatched from patent application
2005/0089418A1:
>
>
>Link to the patent: https://goo.gl/nLh81H
>
>Reading through the patent description, two
>possibilities, both admittedly remote, come to mind:
>
>1. TVS diode D4 has seen too much abuse and has
>failed short. The brief current spike that
>results when power is applied is sufficient to
>blow the fuse but not to blow D4 clear.
If a junction device goes catastrophic it generally
dead shorts or blows open (usually scattering bits
of plastic around). If this diode was shorted,
it would pop the fuse immediately on application
of battery power.
>2. MOSFET Q1 has failed short. The patent
>application says this about the solenoid coil:
>=9CIn a preferred embodiment, [the] coil is made
>of 21 gauge magnet wire and is a 2mH inductor
>with a resistance of 1.4 ohms.=9D With Q1
>shorted, this would draw >8A at 12V, easily blowing a 5A fuse.
I like this one . . . but again, the differential
is that the fuse would blow immediately upon
application of battery power . . . and not
wait for the starter to engage.
>The first failure would probably present as a
>dead short to a continuity meter across the
>pump=99s supply wires. The second might not
>register as a short, but would measure as a very
>low resistance. Either way, putting a meter
>across the pump would prove or debunk my theory.
Bob . . .
Message 12
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
At 12:20 PM 5/22/2018, you wrote:
>
>Without seeing your battery holders and exactly what is wrong, it is
>hard to make a suggestion. But here is a link to battery holders
>and parts from Mouser:
>https://www.mouser.com/Power/Battery-Holders-Clips-Contacts/_/N-cicxgZ1yzvvqx?P=1z0y6wzZ1yuke34
>I have even soldered wires to batteries before using a soldering gun
>and short contact time to minimize damage to the cell. I remember
>that Bob has described welding wires to dry cells, but I can not
>remember how he did it.
I did a comic book on this topic but durned if I can
put my hands on it. The process is pretty simple.
I generally glue the cells together in the shape
of the finished array. A tiny bead of E6000 or similar
at the tangent line of adjacent cells works really
well . . . observe the +/- orientation for future
jumpers . . . they're really hard to get apart after
the glue dries.
I then 'scuff' the solder spot locations with
a Dremel cutoff wheel . . . or file . . . or sharp
knife. Use a fully heated iron to 'tin' the spots . . .
get on, get off quick. 63/37 solder with good flux.
Takes less than a second.
Tin the ends of your jumper/lead wires and then
tack to the solder spots cited above. The
magic dust is a mixture of clean, hot and fast.
I've never damaged an alkaline or NiMh cell
with this technique.
Bob . . .
Message 13
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Subject: | Re: Shower of Sparks |
Excellent Mike,
Best of luck.
Barry
On Mon, May 21, 2018 at 11:04 PM, <mike@vision499.com> wrote:
> Tested my spark again to-day with the Neon spark plug tester.
>
>
> With the Shower of sparks disconnected I could not see a flash in the neo
n
> but it was in very bright light.
>
>
> With the Shower of Sparks connected I could see a very strong flash in
> the neon bulb, assumed all is good.
>
> Will attempt first engine start in the next few weeks and wiil report bac
k
>
>
> Thanks again
>
>
> Mike
>
>
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com] *On Behalf Of *FLYaDIVE
> *Sent:* May 17, 2018 8:52 PM
>
> *To:* aeroelectric-list@matronics.com
> *Subject:* Re: AeroElectric-List: Shower of Sparks
>
>
> Mike:
>
>
> You are quite welcome.
>
>
> Did you notice how long the spark lasted?
>
> Way longer than just a Mag spark.
>
> Easy test.
>
>
> Barry
>
>
> On Thu, May 17, 2018 at 11:19 PM, <mike@vision499.com> wrote:
>
> Thank you very much for the help,
>
>
> The spark plug test light worked like a charm, thanks for the good idea
>
>
> Keep well
>
>
> Mike
>
>
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com] *On Behalf Of *FLYaDIVE
> *Sent:* May 15, 2018 6:05 PM
> *To:* aeroelectric-list@matronics.com
> *Subject:* Re: AeroElectric-List: Shower of Sparks
>
>
> Mike:
>
>
> To test the Shower Of Sparks -
>
> Disconnect the Starter.
>
> You can do this easily by pulling the control wire to the Starter Relay.
>
> This way you can activate the Shower Of Sparks (SOS) and LISTEN for the
> BUZZ and SAFELY not have to worry about a spinning prop.
>
> You can also remove the spark plug wire from each of the spark plugs.
>
> Do you want to check out the Mag and the Spark Plug wires as well as the
> SOS?
>
> If so here is another TRICK!
>
> Go to a automotive store and get the Clear Plastic Spark Plug test
> light... It has a Neon bulb inside.
>
> You hook up the test light to the wires.
>
> Re-Connect the control wire on the starter relay and CRANK AWAY.
>
> You will see a longer time duration to the spark than if there was NO SO
S.
>
> And, it will be a nice bright light. Again as compared to a standard
> Impulse Mag.
>
>
> On Tue, May 15, 2018 at 8:32 PM, <mike@vision499.com> wrote:
>
>
> I have installed a LOM engine with a Shower of Sparks,
>
> 1. How long can I safely keep the unit on (buzzing) while testing it
>
> =8BBarry - I never had a over heating problem. I would guess and e
asy
> Minute.=8B
>
>
> 2. When I turn the motor over and ground the plug to the engine what type
> of spark or sparks should I expect.
>
> =8BBarry - A standard Blueish Spark of Longer Duration.=8B
>
>
> 3. Are there any other tests that I can perform.
>
> =8BBarry - See above.
>
>
> =8BBest of Luck,=8B
>
>
> Barry=8B
>
>
> Thanks
>
> Mike
>
>
> ---
>
>
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm
_campaign=sig-email&utm_content=emailclient>
>
> Virus-free. www.avast.com
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm
_campaign=sig-email&utm_content=emailclient>
>
>
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Joe:
I really do not think I am going to be saying anything that you already do
not know.
12 VDC @ 1 Amp = 12 Watts
Considering the charge voltage at 14.2 VDC the Wattage becomes 14.2 Watts.
If the Voltage drops to half 6 VDC and the pumps is still trying to work,
you have
I = W/6VDC or 14.2 / 6 = 2.37 Amps
12 / 6 = 2 Amps The Amperage Doubles.
The only problem is the Pump is not a restive load it is both resistive and
inductive. So the current draw is not uniform.
It is very possible that the current can well spike to above the fused 5
Amp limit.
The 'solid state' part of the pump is only the opening and closing of the
contacts for the coil.
Which may or may not be able to handle the increased current?
Barry
On Mon, May 21, 2018 at 7:54 PM, user9253 <fransew@gmail.com> wrote:
>
> There is a recent thread on VansAirforce about the electric fuel pump 5
> amp fuse blowing as a result of low battery voltage.
> http://www.vansairforce.com/community/showthread.php?t=160595
> I would have attributed the blown fuse to some other cause, except that
> two pilots reported the same symptoms on two different aircraft. The fuel
> pump is Facet part number 40105. According to Aircraft Spruce, that pump
> draws 1 amp. I measured the current draw on my spare pump (same make and
> model) at 3/4 amp with a light load. When I connected a 6 volt battery to
> the pump instead of 12 volts, the pump quit working and the current dropped
> to about 1/2 amp. I do not have a power supply with adjustable voltage
> output. Does the current draw for a DC pump motor actually increase as the
> voltage decreases? And even if it did, which I doubt, the current would
> have to increase by a factor of 5 in order to blow the fuse.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480282#480282
>
>
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
nuckolls.bob(at)aeroelect wrote:
> If a junction device goes catastrophic it generally dead shorts or blows open
(usually scattering bits of plastic around). If this diode was shorted, it would
pop the fuse immediately on application of battery power.
>
> []
>
> I like this one . . . but again, the differential is that the fuse would blow
immediately upon application of battery power . . . and not wait for the starter
to engage.
Aaah, yes, of course. I think I got led astray when Joe wrote that the fuse blew
upon engine cranking. The fuel pump would obviously already be running by
then.
Unless these aircraft somehow have an unintentional path by which the starter or
its contactor circuit can draw current through the pump fuse, Im out of ideas.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480323#480323
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
The wattage for most electrical loads varies directly with the applied voltage.
As the voltage goes down, so does the current and wattage go down. An exception
is a switching power supply. But it is unlikely that the Facet pump has
a switching power supply. Even if the pump current tripled from 1 amp to 3 amps,
a 5 amp fuse should not blow. Looking at the schematic, there is an electrolytic
capacitor in parallel with the pump, if that matters.
The Facet pump is used in lots of airplanes. If it blew fuses while cranking
the engine with a weak battery, it seems that there would be more reports of
that. My guess is that there is something unique about this one particular airplane.
It will be interesting to learn if a new battery cures the fuse blowing
problem.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480326#480326
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Agreed Joe;
But, as you say 'most'... When a shunt motor gets less voltage the motor
does not stop, it tries to perform the same job as if it had full voltage.
What becomes compensated is the current draw.
Sitting behind a computer as we are; We don't know the condition of the
pump, wires, wire size or connections. And as you say: "My guess is that
there is something unique about this one particular airplane."
I do have Fact pumps: Both the very old 20+ year old and newer 8 year old
styles. I can hook then up to a heavy duty power supply and play with the
voltage and see what results we get. Won't be able to do it till next week
though.
Side Note: Many certified aircraft complete the circuit by completing the
Ground. Grounds have lots of resistance issues.
Barry
On Tue, May 22, 2018 at 7:42 PM, user9253 <fransew@gmail.com> wrote:
>
> The wattage for most electrical loads varies directly with the applied
> voltage. As the voltage goes down, so does the current and wattage go
> down. An exception is a switching power supply. But it is unlikely that
> the Facet pump has a switching power supply. Even if the pump current
> tripled from 1 amp to 3 amps, a 5 amp fuse should not blow. Looking at the
> schematic, there is an electrolytic capacitor in parallel with the pump, if
> that matters.
> The Facet pump is used in lots of airplanes. If it blew fuses while
> cranking the engine with a weak battery, it seems that there would be more
> reports of that. My guess is that there is something unique about this one
> particular airplane. It will be interesting to learn if a new battery
> cures the fuse blowing problem.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480326#480326
>
>
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
But, as you say 'most'... When a shunt motor gets less voltage the
motor does not stop, it tries to perform the same job as if it had
full voltage. What becomes compensated is the current draw.
Shunt, PM and Brushless motor draw current
proportional to load TORQUE. It is
limited at stall by the motor's series
resistance where Eapp/Rohms = Amps which
is proportional to stall torque during
locked rotor conditions.
If a motor is driving a constant torque
load, then current will not go up as
applied voltage is reduced. The speed
will fall off until such time as stall
torque at that voltage is realized whereupon
motion stops.
I do have Fact pumps: Both the very old 20+ year old and newer 8
year old styles. I can hook then up to a heavy duty power supply and
play with the voltage and see what results we get. Won't be able to
do it till next week though.
No Facet pump is driven by the classic
DC motor with a rotating shaft. The Facet
pumps have roots in Bendix designs that
date back to 1920 or earlier. These
are solenoid driven pistons, springs
and check valves that produce one
'squirt' of fuel for each 'thump'
of the solenoid motor. Here's a
partial listing of patents describing
the history of these pumps.
Emacs!
The current draw of these pumps is limited
by resistance of the solenoid winding which
is averaged by the intermittent nature of
the electrical pulse duration. Most
of these pumps have a very low electrical
duty cycle which produces an average current
that is a small fraction of the potential
flow that would manifest if the switching
electronics failed . . . see earlier
schematic posted.
The Facet pumps have no operating characteristics
in common with motor driven fuel pumps. And
no DC motor draws more current with decreasing
voltage UNLESS mechanical load is increasing
as motor speed drops. Given that
pump torque is proportional to output pressure,
we won't see this happening with a rotary
pumping system. I'm not aware of any
load we might drive with a DC motor that
increases torque as rpm falls.
Bob . . .
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Preparing to wire up a small hydraulic pump to operate amphibious float wheels.
Spec sheet on the parker pump unit indicates to use a DPDT center off switch
rated for up to 20A DC at 12V. Looking at B&C S700 series -1. My concern is
that the switch is rated for up to 15 VAC. Equivalent, or should I continue
my search for a switch? If so, any pointers appreciated. [Wink]
Dave (the novice electrician/soon to be float flyer)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480329#480329
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Barry, that is a great idea about using a variable voltage power supply. Wish
I had one. About the pump. It does not have a motor. It is a solenoid driven
piston. The owner of the aircraft intends to fly tomorrow with a new battery.
I am looking forward to his report, to see if a new battery cures the fuel
pump fuse blowing problem while starting the engine.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480331#480331
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
[quote="user9253"]Bob,
Thanks for the reply and explanation about how the pump works. I had neglected
to mention that the fuel pump fuse blows during engine cranking. I do not think
that makes any difference to the pump, other than causing a voltage sag.
I measured the current draw of my spare pump with an analog Simpson 260. I am
as mystified as you. Unfortunately the plane is located hundreds of miles away.
All I have to go by is second hand information.[/quote]
I've read through the comments as well as the Vans forum posts Joe references and
have something to add that might confuse the issue even more (or maybe not).
I'm a member of a flying club with 5 Piper Cherokees and one Mooney. Last fall
one of the members reported the same problem (fuel pump failed during cranking).
I doubted the two events were related and asked the A&P the club used, to
replace the fuse and I would watch the problem. A few days later the fuse (allegedly)
blew again during the cranking cycle. Again, I doubted the cranking
had anything to do with the fuse. It did not make any sense to me. I should
note, that this plane was also having an intermittent problem with a "tired battery"
during starting, particularly, now that the weather was getting colder
(I should note, this was last fall in Minnesota).
A day or so after the fuse was replaced the second time I took the plane for a
flight myself. Pre-flight went fine and I started the fuel pump and began to
crank the engine. The weather was probably 30 degrees and the battery had a hard
time turning the engine. After the flight I checked the fuel pump again and
sure enough, it's fuse had blown.
I was perplexed as to how the fuel pump fuse failure could be related to starting
the engine. Lower voltage during cranking was likely but I assumed this would
also result in lower current (as noted by many in this post). So, I assumed
there might be something wrong with the fuel pump and had the A&P install
a new one.
Within a few days after the new fuel pump was installed, the problem resurfaced.
Throughout all of this, the battery continued to be an issue when starting
with a cold engine. Winter was coming and the battery problem would only get
worse. The battery passed the A&P's load testing but it was at least 4 years
old. So, following the best advice from the Aeroelectric connection, I asked
the A&P to replace the battery with an RG (Recumbent Gas) battery.
Problem solved. Plane started all winter without fail and no more blown fuel pump
fuses.
My only thought was that the low battery was resulting in a voltage spike, immediately
after starting. The high voltage spike that would catch the fuel pump
with high voltage and create an over current situation. It could be that the
regulator on this plane allowed for higher than normal voltages. I did check
the JPI data on the plane and yes, there were many small events that showed
up to 15.1 volts but we generally don't have avionics powered up until after
starting so there was no JPI data during the start cycle. I think the regulator
could be set a little higher on this plane or it may have a tendency to overshoot.
I don't have enough details prove this out.
In any case, replacing the fuel pump did not solve the problem. Replacing the
battery did and I've not seen this issue on any other planes but their JPI records
did not show the high voltage events that this Archer did.
For what its worth...
Dan Theis.
--------
Scratch building Sonex #1362
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480332#480332
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Thanks Dan for that report. So it seems that the Facet fuel pump current
does go up during engine cranking.
To others, how can this be explained by the laws of physics?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480333#480333
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Joe:
You just made me think ... I wonder... What would happen if the boost pump
was installed backwards?
Not electrically, since that part is solid-state.
I WILL run the test next week.
Barry
On Tue, May 22, 2018 at 10:17 PM, user9253 <fransew@gmail.com> wrote:
>
> Barry, that is a great idea about using a variable voltage power supply.
> Wish I had one. About the pump. It does not have a motor. It is a
> solenoid driven piston. The owner of the aircraft intends to fly tomorrow
> with a new battery. I am looking forward to his report, to see if a new
> battery cures the fuel pump fuse blowing problem while starting the engine.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480331#480331
>
>
Message 24
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
Gaggle:
Just had another thought... I know this to be an issue with Grumman's.
The Boost Pump and the Strobes are on the same fuse.
And when things are handled wrong - The fuse pops.
So, the procedure for starting is:
All lights off - Except for the rotating beacon - UNLESS you do not have a
rotating beacon.
Boost Pump - ON
Wait for fuel pressure to build and clicking to slow down.
Boost Pump - OFF
Start Engine.
Bring the rest of the plane On-Line - Lights and Avionics.
Barry
On Tue, May 22, 2018 at 10:26 PM, dj_theis <djtheis58@gmail.com> wrote:
>
> [quote="user9253"]Bob,
> Thanks for the reply and explanation about how the pump works. I had
> neglected to mention that the fuel pump fuse blows during engine cranking.
> I do not think that makes any difference to the pump, other than causing a
> voltage sag. I measured the current draw of my spare pump with an analog
> Simpson 260. I am as mystified as you. Unfortunately the plane is located
> hundreds of miles away. All I have to go by is second hand
> information.[/quote]
>
> I've read through the comments as well as the Vans forum posts Joe
> references and have something to add that might confuse the issue even more
> (or maybe not).
> I'm a member of a flying club with 5 Piper Cherokees and one Mooney. Last
> fall one of the members reported the same problem (fuel pump failed during
> cranking). I doubted the two events were related and asked the A&P the
> club used, to replace the fuse and I would watch the problem. A few days
> later the fuse (allegedly) blew again during the cranking cycle. Again, I
> doubted the cranking had anything to do with the fuse. It did not make any
> sense to me. I should note, that this plane was also having an
> intermittent problem with a "tired battery" during starting, particularly,
> now that the weather was getting colder (I should note, this was last fall
> in Minnesota).
>
> A day or so after the fuse was replaced the second time I took the plane
> for a flight myself. Pre-flight went fine and I started the fuel pump and
> began to crank the engine. The weather was probably 30 degrees and the
> battery had a hard time turning the engine. After the flight I checked the
> fuel pump again and sure enough, it's fuse had blown.
>
> I was perplexed as to how the fuel pump fuse failure could be related to
> starting the engine. Lower voltage during cranking was likely but I
> assumed this would also result in lower current (as noted by many in this
> post). So, I assumed there might be something wrong with the fuel pump and
> had the A&P install a new one.
>
> Within a few days after the new fuel pump was installed, the problem
> resurfaced. Throughout all of this, the battery continued to be an issue
> when starting with a cold engine. Winter was coming and the battery
> problem would only get worse. The battery passed the A&P's load testing
> but it was at least 4 years old. So, following the best advice from the
> Aeroelectric connection, I asked the A&P to replace the battery with an RG
> (Recumbent Gas) battery.
>
> Problem solved. Plane started all winter without fail and no more blown
> fuel pump fuses.
>
> My only thought was that the low battery was resulting in a voltage spike,
> immediately after starting. The high voltage spike that would catch the
> fuel pump with high voltage and create an over current situation. It
> could be that the regulator on this plane allowed for higher than normal
> voltages. I did check the JPI data on the plane and yes, there were many
> small events that showed up to 15.1 volts but we generally don't have
> avionics powered up until after starting so there was no JPI data during
> the start cycle. I think the regulator could be set a little higher on
> this plane or it may have a tendency to overshoot. I don't have enough
> details prove this out.
>
> In any case, replacing the fuel pump did not solve the problem. Replacing
> the battery did and I've not seen this issue on any other planes but their
> JPI records did not show the high voltage events that this Archer did.
>
> For what its worth...
>
> Dan Theis.
>
> --------
> Scratch building Sonex #1362
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480332#480332
>
>
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Subject: | Re: B&C switches |
At 08:09 PM 5/22/2018, you wrote:
>
>Preparing to wire up a small hydraulic pump to operate amphibious
>float wheels.
>Spec sheet on the parker pump unit indicates to use a DPDT center off switch
>rated for up to 20A DC at 12V. Looking at B&C S700 series -1. My
>concern is that the switch is rated for up to 15 VAC. Equivalent,
>or should I continue my search for a switch? If so, any pointers
>appreciated. [Wink]
>
>Dave (the novice electrician/soon to be float flyer)
What's the make and part number for the pump/motor
you're working with?
Bob . . .
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Subject: | Re: Low Battery Voltage Blows Fuel Pump Fuse? |
>
>Within a few days after the new fuel pump was installed, the problem
>resurfaced. Throughout all of this, the battery continued to be an
>issue when starting with a cold engine. Winter was coming and the
>battery problem would only get worse. The battery passed the A&P's
>load testing but it was at least 4 years old. So, following the
>best advice from the Aeroelectric connection, I asked the A&P to
>replace the battery with an RG (Recumbent Gas) battery.
>
>Problem solved. Plane started all winter without fail and no more
>blown fuel pump fuses.
>
>My only thought was that the low battery was resulting in a voltage
>spike, immediately after starting. The high voltage spike that
>would catch the fuel pump with high voltage and create an over
>current situation. It could be that the regulator on this plane
>allowed for higher than normal voltages. I did check the JPI data
>on the plane and yes, there were many small events that showed up to
>15.1 volts but we generally don't have avionics powered up until
>after starting so there was no JPI data during the start cycle. I
>think the regulator could be set a little higher on this plane or it
>may have a tendency to overshoot. I don't have enough details prove this out.
>
>In any case, replacing the fuel pump did not solve the
>problem. Replacing the battery did and I've not seen this issue on
>any other planes but their JPI records did not show the high voltage
>events that this Archer did.
Good data . . . and I think some pieces are
falling into place.
The 555 astable multivibrator driving the pump's
fet is set up to turn the fet on hard and apply
full 12v to a coil with about 1 ohm resistance.
Under normal ops, this produces a power pulse to
the 'spring winder' on the order of 12A but
only for a few tens of milliseconds out
of every cycle such that AVERAGE current
flowing is low . . . 1 to 2A.
I'm thinking the 555 multi-vibrator becomes
uncertain during a brown out event . . . and
produces a longer power pulse. Recall that
unlike breakers, fuses can be 'hammered' with
repeated over-loads.
Running a pump on the bench with a variable
supply would confirm out-of-spec operation
for the pump's electronics during the brown-out
event.
It would be easy to design a pulse generator
that would stay in spec down to much lower
voltages . . . but this is probably not
a situation that would get Faucet's attention.
Bob . . .
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