Today's Message Index:
----------------------
1. 06:21 AM - Re: Solar & Wind Power (Eric M. Jones)
2. 08:26 AM - Engine mount as starter ground path (Jeff Page)
3. 10:15 AM - Re: Engine mount as starter ground path (John Cox)
4. 10:52 AM - Re: Engine mount as starter ground path ()
5. 12:30 PM - Re: Crowbar (johngoodman)
6. 01:31 PM - Re: Re: Crowbar (Robert L. Nuckolls, III)
7. 01:56 PM - Re: Engine mount as starter ground path (Robert L. Nuckolls, III)
8. 02:22 PM - Re: Engine mount as starter ground path (Kelly McMullen)
9. 02:22 PM - Re: Engine mount as starter ground path (Vaughn Teegarden)
10. 02:37 PM - Re: Engine mount as starter ground path (Hinde, Frank George (Corvallis))
11. 03:47 PM - Rotax 912ULS voltage . . . (Robert L. Nuckolls, III)
12. 03:51 PM - Re: Engine mount as starter ground path (Robert L. Nuckolls, III)
13. 03:53 PM - Re: Ground Power Receptacle - 3 pin (Robert L. Nuckolls, III)
14. 04:06 PM - Re: Alternator Failure (Robert L. Nuckolls, III)
15. 04:06 PM - Re: LR3 regulator Amperage indications (Robert L. Nuckolls, III)
16. 04:08 PM - Re: LR3 regulator Amperage indications (Robert L. Nuckolls, III)
17. 06:16 PM - ARC R-402A Pin Out (Michael Estu)
18. 06:49 PM - Re: Engine mount as starter ground path (Bill Mauledriver Watson)
19. 07:28 PM - Re: LR3 regulator Amperage indications (Bob Meyers)
20. 07:57 PM - Re: ARC R-402A Pin Out (Matt Prather)
21. 09:38 PM - Engine mount as starter ground path (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Solar & Wind Power |
Besides, there is nothing that encourages wild speculation as knowing nothing about
it...and a few beers.
Instead, google "Home Power" magazine online (and print). They have everything
and lots of archives. The internet is a wealth of information on the subject.
"The problem with the world is that only the intelligent people want to be
smarter, and only the good people want to improve."
- Eolake Stobblehouse
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=245377#245377
Message 2
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Subject: | Engine mount as starter ground path |
Does anyone have some scientific information (beyond the practical
description in the Connection) that I can use to convince someone that
running the engine ground strap to the engine mount is a poor choice ?
Thanks !
Jeff Page
Dream Aircraft Tundra #10
Message 3
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Subject: | Engine mount as starter ground path |
Totally separate but possibly dead on. My 1978 Ford pickup suffered
catastrophic electrolysis of the cab floorboards and the entire bed
(years 28-31). The Tailgate was replaced with an Electro-Hydraulic
1,000 pound Tommy Lift. The lift motor used high current capacity
welding cable with neoprene shielding for the Positive. NO GROUND.
Just the mounting to the bed of the truck and the frame rails. All of a
sudden over the last several years, the truck began rapid corrosion
(Really Rapid - Decomposition).
My conclusion. Stray electrons looking for the primary path to ground -
found their path without the aid of the missing ground. My action -
Never again! use a structural mount in hopes of taking a path of less
effort during installation. Provide an adequate ground from the battery
or generator source. Listen to Bob. Semi-monocoque construction makes
it even more valid.
YMMV.
John Cox
Now for the experts.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jeff
Page
Sent: Tuesday, May 26, 2009 8:14 AM
Subject: AeroElectric-List: Engine mount as starter ground path
Does anyone have some scientific information (beyond the practical
description in the Connection) that I can use to convince someone that
running the engine ground strap to the engine mount is a poor choice ?
Thanks !
Jeff Page
Dream Aircraft Tundra #10
Message 4
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Subject: | Engine mount as starter ground path |
How about the scientific principle of rubber engine mounts being a poor
conductor of electricity? That would go for the cadmium plating on the
bolts themselves. Not a perfect conductor. Scientifically engine
mounting bolts will corrode over time, get oily and generally loose what
connectivity they have.
Under Ohm's law the addition of the engine mount changes sub R in the
equation reducing the conductance value of the material. If he works out
the equation using the combined values conductivity will be less. After
he is done scratching his head, he'll recognize why it's done this way.
See: http://en.wikipedia.org/wiki/Electrical_conductance
If he is trying to save $3.00 on the cost of the additional 5" of cable
required to anchor it to the engine, there is little argument on his
side.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jeff
Page
Sent: Tuesday, May 26, 2009 11:14 AM
Subject: AeroElectric-List: Engine mount as starter ground path
Does anyone have some scientific information (beyond the practical
description in the Connection) that I can use to convince someone that
running the engine ground strap to the engine mount is a poor choice ?
Thanks !
Jeff Page
Dream Aircraft Tundra #10
Message 5
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Bob,
I'm following the Z-31A schematic for a military style ground power jack, and I'm
ordering parts. I've found everything except for the OVM-14 Crowbar O.V. Module.
I called B&C sales and they referred me to a part number 504-1 , which is
something for an alternator with a lot of pieces. How do I get just the OVM-14?
John
--------
#40572 QB Fuselage, wings finished. Finish Kit started.
N711JG reserved
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=245430#245430
Message 6
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At 02:25 PM 5/26/2009, you wrote:
><johngoodman@earthlink.net>
>
>Bob,
>I'm following the Z-31A schematic for a military style ground power
>jack, and I'm ordering parts. I've found everything except for the
>OVM-14 Crowbar O.V. Module. I called B&C sales and they referred me
>to a part number 504-1 , which is something for an alternator with a
>lot of pieces. How do I get just the OVM-14?
They're in production in our shop now. I don't have
them on the catalog yet. Fill out an order at:
https://matronics.com/aeroelectric/Catalog/AECcatalog.html
and put "1ea CbOVM-14 @ $25.00" in the comments box.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 7
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Subject: | Re: Engine mount as starter ground path |
At 10:14 AM 5/26/2009, you wrote:
>
>Does anyone have some scientific information (beyond the practical
>description in the Connection) that I can use to convince someone that
>running the engine ground strap to the engine mount is a poor choice ?
>
>Thanks !
The shortest, lowest resistance and minimum parts count path
in any high current conduction path is the road to Ground
System Nirvana. See:
http://www.aeroelectric.com/articles/grnding.pdf
Engine mounts are steel assembled with steel
hardware. The joints between mounts and other
components of the airframe are not treated for
the purpose of electrical "bonding". The engine
mount is intended to hold the engine on the
airplane and was not designed or installed to
be a part of the electrical system.
Note that Figure Z-15 and Chapter 5 of the
'Connection speak to and illustrate a notion
that engines are best tied to the single point
fire-wall ground block with a single-flexible-
fatwire. To avoid having the firewall sheet
participate in a PARALLEL ground path (read
ground loop) any bonding jumpers across the
engine mounts are best removed.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 8
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Subject: | Re: Engine mount as starter ground path |
Given such a ground path, how does one get lineboys trained that the
engine exhaust pipe is a terrible place for ground wire, that the fuel
tanks are in the wings, and something like a bare spot on wing tiedown
has a much shorter ground path? I always wonder how static charge is
supposed to make it from the fuel tank through the airframe to the
engine and down the rusty, carboned up exhaust pipe, usually with a
swivel or slip joint or two to that ground wire, without significant
resistance.
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 10:14 AM 5/26/2009, you wrote:
>>
>> Does anyone have some scientific information (beyond the practical
>> description in the Connection) that I can use to convince someone that
>> running the engine ground strap to the engine mount is a poor choice ?
>>
>> Thanks !
>
> The shortest, lowest resistance and minimum parts count path
> in any high current conduction path is the road to Ground
> System Nirvana. See:
>
> http://www.aeroelectric.com/articles/grnding.pdf
>
> Engine mounts are steel assembled with steel
> hardware. The joints between mounts and other
> components of the airframe are not treated for
> the purpose of electrical "bonding". The engine
> mount is intended to hold the engine on the
> airplane and was not designed or installed to
> be a part of the electrical system.
>
> Note that Figure Z-15 and Chapter 5 of the
> 'Connection speak to and illustrate a notion
> that engines are best tied to the single point
> fire-wall ground block with a single-flexible-
> fatwire. To avoid having the firewall sheet
> participate in a PARALLEL ground path (read
> ground loop) any bonding jumpers across the
> engine mounts are best removed.
>
>
> Bob . . .
>
>
Message 9
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Subject: | Re: Engine mount as starter ground path |
How about some anecdotal evidence. I had a Cadillac 4.9 liter V8 installed
in my Pontiac Fiero. Since it weighted 15 pounds more than the V6 that was
in there, I had the battery moved from the rear engine compartment to just
on top of the front axle. My voltmeter would not show over 13.5 volts even
when the battery was weak and would drop below 12 volts if I ran the AC and
lights at the same time. I would also have intermittent problems starting
the car when it was hot. The battery was grounded to the frame and the
engine was also grounded to the frame. A 9 foot #2 wire went from the
positive terminal to the starter. After putting on a new starter the engine
would not start hot the very first time I drove it somewhere. I put a 9 foot
#2 wire from the negative side of the battery to the one of the mounting
studs of the starter and now no more starting problems. The voltmeter shows
14.5 volts on start-up and after a brief drop when turning on the lights and
AC, it shows 13.5 volts. The ground is important. I only wish it hadn't
taken me 2 years to figure it out.
Vaughn Teegarden
----- Original Message -----
From: "Jeff Page" <jpx@Qenesis.com>
Sent: Tuesday, May 26, 2009 11:14
Subject: AeroElectric-List: Engine mount as starter ground path
>
> Does anyone have some scientific information (beyond the practical
> description in the Connection) that I can use to convince someone that
> running the engine ground strap to the engine mount is a poor choice ?
>
> Thanks !
>
> Jeff Page
> Dream Aircraft Tundra #10
>
>
>
Message 10
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Subject: | Engine mount as starter ground path |
Just be thankful your ground path didn't go thru your crank bearings..You would
have figured itout a lot sooner though..:)
Frank
RV 7a and a tractor where the battery negative goes directly to the starter as
well!
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vaughn Teegarden
Sent: Tuesday, May 26, 2009 2:22 PM
Subject: Re: AeroElectric-List: Engine mount as starter ground path
--> <europaul260i@bvunet.net>
How about some anecdotal evidence. I had a Cadillac 4.9 liter V8 installed in my
Pontiac Fiero. Since it weighted 15 pounds more than the V6 that was in there,
I had the battery moved from the rear engine compartment to just on top of
the front axle. My voltmeter would not show over 13.5 volts even when the battery
was weak and would drop below 12 volts if I ran the AC and lights at the same
time. I would also have intermittent problems starting the car when it was
hot. The battery was grounded to the frame and the engine was also grounded to
the frame. A 9 foot #2 wire went from the positive terminal to the starter.
After putting on a new starter the engine would not start hot the very first time
I drove it somewhere. I put a 9 foot
#2 wire from the negative side of the battery to the one of the mounting studs
of the starter and now no more starting problems. The voltmeter shows
14.5 volts on start-up and after a brief drop when turning on the lights and AC,
it shows 13.5 volts. The ground is important. I only wish it hadn't taken me
2 years to figure it out.
Vaughn Teegarden
Message 11
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Subject: | Rotax 912ULS voltage . . . |
At 12:38 AM 5/26/2009, you wrote:
Thank you for the information Bob.
I am trying to trouble shoot my low voltage problem to determine its
cause (i.e.; the regulator, wiring, or the internal engine
alternator) so I can take corrective action.
There is nothing in the Rotax 912 manuals to assist in doing this. I
checked the internal engine coil resistance reading and found it to
be .7-ohms. The DC voltage at the regulator is the same previously
reported (still under 13-volts). Finally I measured AC voltage coming
from the coils. The voltage varied as follows:
Idle (1900-RPM) was 12.8 volts
2500-RPM was 16.0 v
3000-RPM was 19.0 v
4000-RPM was 24.5 v
cruse(5000-RPM)was not measured.
Bob, Am I correct to think that the AC voltage looks adequate and the
problem is likely a faulty Rotax voltage regulator?
Thanks again for your help.
If you have ANY voltage from the alternator's output winding
at any speed, and the winding is not shorted to ground (very
unlikely) then the alternator is fine. Rotax PM alternators are
exceedingly simple, rugged and reliable. I'm not aware of any
failures.
The Ducati rectifier/regulator supplied with these engines
is another matter. They are of marginal thermal design and
sadly lacking in adjustability. Two conditions VERY
easy to fix if anyone with responsibility for the product
cared.
Unfortunately, replacing it with an identical OEM R/R has
a high probability of installing a similar problem right
out of the box. I've heard that John Deere has a single
phase, PM alternator regulator that is rated for up to
35 amps. Goto http://matronics.com/search
Search the AeroElectric List for AM101406 and you'll
get several hits by folks who discussed it some time
back.
Here are some after-market clones . . .
http://www.watercraftstarter.com/Lawn%20Garden/Regulator%20Rectifier/?nocache=1
http://www.amazon.com/Replacement-Voltage-Regulator-Deere-AM101406/dp/B00169H3E0
I don't see a voltage adjustment mentioned or
shown . . . unfortunate but perhaps understandable.
Most of these regulators are used on small tractors
and most users are not skilled in the use of such
features.
Wish I had my alternator drive stand running. Building
a 'real' PM r/r for aircraft is not a big task . . .
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 12
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Subject: | Re: Engine mount as starter ground path |
At 04:21 PM 5/26/2009, you wrote:
>Given such a ground path, how does one get lineboys trained that the
>engine exhaust pipe is a terrible place for ground wire, that the
>fuel tanks are in the wings, and something like a bare spot on wing
>tiedown has a much shorter ground path? I always wonder how static
>charge is supposed to make it from the fuel tank through the
>airframe to the engine and down the rusty, carboned up exhaust pipe,
>usually with a swivel or slip joint or two to that ground wire,
>without significant resistance.
The line boy's ground lead is not intended to carry
more than micro-amps of current . . . and then for
only enough time to equalize the STATIC charge on
the airplane with the STATIC charge on the fuel truck.
Given the proliferation of composite aircraft it's
not a bad bet for fuel truck operators to use the exhaust
pipe . . . it's metallic and definitely connected to
the crankcase through other metallic parts. Now, it's
entirely possible that a metallic tank resides in a
composite wing and is plumbed up with some modern
synthetic tubing . . . it's a tiny bit of a crap-shoot.
Bottom line is that the rusty, gunked up piece of pipe
is not a bad choice.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 13
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Subject: | Re: Ground Power Receptacle - 3 pin |
At 10:13 PM 5/25/2009, you wrote:
><paulmillner@compuserve.com>
>
> >> I assume that the military and airlines use the pin for the same thing.
>
>In the 70's, Cessna used that small third pin, hotted up by the
>external power source, to both close the ground power contactor,
>connecting the external power source to the bus, *and* to energize
>an avionics relay, which disconnected the avionics bus from the main
>bus. The relay coil was diode or'd with the starter contactor coil
>circuit... so turning the key to start *also* disconnected the avionics bus.
>
>Where it gets exciting is when the diode from the starter contactor
>fails as a short.. then, connecting ground power causes the prop to
>start spinning, Youza!
Yeah . . . I remember that setup. We sure thought
it was a good idea . . . at the time . . .
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 14
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Subject: | Re: Alternator Failure |
At 04:31 PM 5/25/2009, you wrote:
><franz@lastfrontierheli.com>
>
>Hi Bob,
>Just letting you know that after some trouble shooting I found the culprit
>of my problems, a loose connection that I overlooked many times, all is
>working as it should again
>Thanks
>Franz
Very good sir. Keep the dirty side down and the pointy
end forward!
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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Subject: | Re: LR3 regulator Amperage indications |
At 06:09 PM 5/25/2009, you wrote:
>
>Not sure if this is relevant to your situation, but I just had a similar
>experience with the EXPBUS output to the alternator. The IRF4905 MOSFET
>that was controlling the 12V to the alternator was measuring 12V with no
>load, but when connected to the alternator dropped to a low voltage.
>Replacing that device on the EXPBUS resolved my problem, as of
>today. ;-)
>
>The ammeter output was totally confusing during this time, in that it
>was indicating 2A, but may have actually been indicating no charging
>current at all. The battery was certainly discharging with minimal
>loads.
>
>If the LR3 "solid state" components include a similar device to the
>IRF4905 it seems it's not so simple as just measuring the voltage at the
>output, since it seems to drop as soon as a load is applied if faulty.
Not exactly . . . The mosfet in the EXP bus appears to
be used as a ON/OFF switch in the feature labeled OV CUTOFF.
It should be turned on hard at all times when not OV-tripped
so as to not upset regulator performance downstream.
Emacs!
The LR3 does have a series control device used as part of
the voltage regulator system. The LR3 also features its own
ov protection that would NOT be compatible with an EXP BUS
installation. Bill cited a voltage reading on the order of
4.5 volts on the wire between circuit breaker and the field
terminal of the LR3 . . . this would cause the LR3 output
to be similarly depressed.
There's either something "unhooked" between the field supply
breaker and the field power terminal of the LR3 . . . or the
battery is REALLY soggy.
Bob. . .
Message 16
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Subject: | Re: LR3 regulator Amperage indications |
At 03:50 PM 5/25/2009, you wrote:
>
>Bob, an update -- The Battery, alternator, and LR3C are fine, the
>symptoms below are attributed to operator induced problems.
>
>1. Apparently when hooking up for the test, I caused a short that
>blew the fuse to the alternator field. That is the reason for the
>battery not charging.
>
>2. I talked to B&C, and downloaded there diagnostic check sheet.
>This led to the discovery of the blown fuse.
>
>3. I have installed an old fashioned 50mv/60A shunt in the B lead,
>and hooked it up to a DVM. Alternator working fine, hash on recorded
>output must be as you originally surmised, the result of noise.
>
>I have not yet tried to filter the noise, now that I know the output
>is stable, I can ignore the chart until I have time to fix it.
>
>Thanks for your help/input.
Aha! funny thing about those pesky electrons. The
alchemists have been trying to teach them how to jump
gaps for centuries . . . no joy.
If you have an LR3, it should have no fuses in the
field supply lead, only a 5A breaker and perhaps a
fusible link as illustrated in Z14.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 17
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Subject: | ARC R-402A Pin Out |
I have an aircraft with an MX-300 radio and an ARC R-402A marker beacon rec
eiver. There is an unlabeled-mystery switch in the panel that leads to th
e marker beacon receiver. Anyone know what this switch is for, and is a pin
out diagram available?
-
Thanks, Mike=0A=0A=0A
Message 18
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Subject: | Re: Engine mount as starter ground path |
The Z-14 I've put into my RV10 follows the best practices as described
in the Connection with one oversight.... I have the 2 sided forest of
tabs on the firewall but I only have an AWG 8 cable running to it from
the rear batteries instead of an AWG2 fat wire. And it's too late to
swap it out without significant re-work.
The isssue is how to get the engine adequately grounded for the
start. I remember this same situation being discussed recently on
either the RV10 or AeroConnection list but I'd like to get some more
input regarding my choices as I see it.
Choice1: Run a flat fat wire (AWG 2 equivalent) from the forest of tabs
lug to the engine and keep the engine mount out of the circuit. Here
I'm depending on the AWG 8 cable and the firewall to provide and
adequate ground for starting. I feel that I do have a solidly grounded
airframe and it is a metal fuselage.
Choice2: Ground the engine to the mount per Van's wiring diagram - 2
straps from the mount to the engine and relying on the 6 mount bolts to
provide what they're not designed to provide. Here I'm trusting that
the steel engine mount will work as a working part of my electrical
system - clearly this is what the Connection is steering me away from.
Choice3: Do both 1 and 2 which gives me a better chance of an adequate
ground than either choice alone gives me, but I run the risk of ground
loops. (what is the potential impact of ground loops in the starter
circuit? Does this introduce potential ground loop problems to systems
connected to the forest of tabs?)
Bob, thanks for covering the same ground over and over!
Bill "enjoying panel wiring and fiberglassing at the same time" Watson
RV10 40605
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 10:14 AM 5/26/2009, you wrote:
>>
>> Does anyone have some scientific information (beyond the practical
>> description in the Connection) that I can use to convince someone that
>> running the engine ground strap to the engine mount is a poor choice ?
>>
>> Thanks !
>
> The shortest, lowest resistance and minimum parts count path
> in any high current conduction path is the road to Ground
> System Nirvana. See:
>
> http://www.aeroelectric.com/articles/grnding.pdf
>
Message 19
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Subject: | Re: LR3 regulator Amperage indications |
Hi Bill.
I was out at Aurora today and once last week. Both times I remembered
your plane was out there but had forgotten to contact you to see if
you would be around. I'm flying again out of Gauntlet Warbirds at
least once a week. I'll be there next Monday if the weather is good.
If you'd like to show off your plane, I would be delighted to see it.
How often are you around out there?
Take care, good to see your making progress with the issue you posted.
Bob Meyers
Building Sonex 982SX Web Site Index http://meyersfamily.org/Sonex982.html
On May 25, 2009, at 3:50 PM, Bill Schertz wrote:
> >
>
> Bob, an update -- The Battery, alternator, and LR3C are fine, the
> symptoms below are attributed to operator induced problems.
>
> 1. Apparently when hooking up for the test, I caused a short that
> blew the fuse to the alternator field. That is the reason for the
> battery not charging.
>
> 2. I talked to B&C, and downloaded there diagnostic check sheet.
> This led to the discovery of the blown fuse.
>
> 3. I have installed an old fashioned 50mv/60A shunt in the B lead,
> and hooked it up to a DVM. Alternator working fine, hash on recorded
> output must be as you originally surmised, the result of noise.
>
> I have not yet tried to filter the noise, now that I know the output
> is stable, I can ignore the chart until I have time to fix it.
>
> Thanks for your help/input.
>
> Bill Schertz
> KIS Cruiser #4045
> N343BS
> Phase I testing
> ----- Original Message ----- From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com
> >
> To: <aeroelectric-list@matronics.com>
> Sent: Monday, May 25, 2009 3:26 PM
> Subject: Re: AeroElectric-List: LR3 regulator Amperage indications
>
>
>> >
>>
>> At 06:12 AM 5/18/2009, you wrote:
>>> >
>>>
>>> Bob,
>>> I am now convinced that the variations were real. I inserted an
>>> ammeter into the field line, while the engine was stopped. Got a
>>> reading of 3.5 amps. Then took the plane out, fired it up with the
>>> ammeter in place, and when the alternator switch was turned on,
>>> the current went to 3.5 amps for a very short time, then dropped
>>> to zero. At that point, it stayed at zero, and the battery would
>>> not charge.
>>>
>>> Put plane back in hanger, and did some static measurements.
>>>
>>> Voltage from LR-3 to field circuit breaker ~4.5 volts
>>
>> This voltage comes FROM your battery via the contactor,
>> main bus, alternator field breaker and switch. When
>> you made these measurements, was the battery charged
>> at all? Or was it down to 4.5 volts?
>>
>>> Voltage at connector to alternator (black plug) ~4.5V
>>
>>
>>> Resistance to ground through the leads that field current plugs
>>> into varies (jumps around) and then often goes to open circuit.
>>>
>>> Could the slip rings be contaminated or not in contact?
>>
>> This is a possibility. You need to deduce the
>> reason for such low voltage readings. Put
>> a charger/maintainer on your battery and make
>> sure it's 100% before you continue the investigation.
>>
>>
>>
>> Bob . . .
>>
>> ----------------------------------------)
>> ( . . . a long habit of not thinking )
>> ( a thing wrong, gives it a superficial )
>> ( appearance of being right . . . )
>> ( )
>> ( -Thomas Paine 1776- )
>> ----------------------------------------
>>
>>
>>
>>
>>
>>
>
>
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Subject: | Re: ARC R-402A Pin Out |
Is the switch MB sensitivity?
Matt-
> I have an aircraft with an MX-300 radio and an ARC R-402A marker beacon
> receiver. There is an unlabeledmystery switch in the panel that leads to
> the marker beacon receiver. Anyone know what this switch is for, and is a
> pin out diagram available?
>
> Thanks, Mike
>
>
Message 21
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Subject: | Engine mount as starter ground path |
t 08:47 PM 5/26/2009, you wrote:
<MauleDriver@nc.rr.com>
The Z-14 I've put into my RV10 follows the best practices as
described in the Connection with one oversight.... I have the 2 sided
forest of tabs on the firewall but I only have an AWG 8
cable running to it from the rear batteries instead of an AWG2 fat
wire. And it's too late to swap it out without significant re-work.
Is this the ONLY ground for the rear-mounted batteries?
8AWG is waaayyyy too small. Pull it out and ground the
battery(ies) locally to the airframe.
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_1.jpg
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_2.jpg
http://aeroelectric.com/Pictures/Grounding/Local_Battery_Grounds_1.jpg
The isssue is how to get the engine adequately grounded for the
start. I remember this same situation being discussed recently on
either the RV10 or AeroConnection list but I'd like to get some more
input regarding my choices as I see it.
Choice1: Run a flat fat wire (AWG 2 equivalent) from the forest of
tabs lug to the engine and keep the engine mount out of the circuit.
This is a given . . . no matter what the
rest of the ground system looks like.
Here I'm depending on the AWG 8 cable and the firewall to provide
and adequate ground for starting. I feel that I do have a solidly
grounded airframe and it is a metal fuselage.
I'm not sure from your description where the ends
of the 8AWG wire are tied. This size of
wire is too small for any significant starter
performance.
Choice2: Ground the engine to the mount per Van's wiring diagram - 2
straps from the mount to the engine and relying on the 6 mount bolts
to provide what they're not designed to provide. Here I'm trusting
that the steel engine mount will work as a working part of
my electrical system - clearly this is what the Connection is
steering me away from.
It's been done before. Leave it alone.
Choice3: Do both 1 and 2 which gives me a better chance of an
adequate ground than either choice alone gives me, but I run the risk
of ground loops. (what is the potential impact of ground loops in
the starter circuit? Does this introduce potential ground loop
problems to systems connected to the forest of tabs?)
Do them both and ground the batteries
to the airframe. The 8AWG wire can be
cut loose and pulled out.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
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