Today's Message Index:
----------------------
1. 04:35 AM - multiple shield ground wires (jayb)
2. 05:01 AM - EGT Readings Change when Transmitting (ChangDriver)
3. 07:55 AM - Re: EGT Readings Change when Transmitting (Robert L. Nuckolls, III)
4. 08:09 AM - Re: Electrical System Drawing (Robert L. Nuckolls, III)
5. 08:10 AM - Re: multiple shield ground wires (Robert L. Nuckolls, III)
6. 10:43 AM - Re: multiple shield ground wires (jayb)
7. 12:00 PM - Re: Electrical System Drawing (Robert L. Nuckolls, III)
8. 12:08 PM - Re: Re: Circuit Design Software (Noel Loveys)
9. 12:35 PM - Re: It's nice when the center holds . . . (Noel Loveys)
10. 01:08 PM - Re: EGT Readings Change when Transmitting (Keith Ward)
11. 01:21 PM - Over Voltage Protection for Internal Regulated Alternators (Bubblehead)
12. 01:36 PM - Re: Electrical System Drawing (Paul Zimmer)
13. 05:45 PM - Drawing Z-13/20 (Paul Zimmer)
14. 06:45 PM - Re: Re: multiple shield ground wires (Robert L. Nuckolls, III)
15. 07:02 PM - Re: Over Voltage Protection for Internal Regulated Alternators (Robert L. Nuckolls, III)
Message 1
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| Subject: | multiple shield ground wires |
When multiple shielded wires pass through a common connector ... Does each shield
need its own separate pin or can several shields be ganged together in a single
pin? Shields eventually come together at a common ground point someplace,
right?
Thanks,
Jay
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346749#346749
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| Subject: | EGT Readings Change when Transmitting |
Bob:
I have noticed an odd thing happening on my digital EGT display. When I key the
microphone to transmit on the Garmin SL-30, the graphical EGT display bars are
driven down to zero. I short key of the mic and they go down a little....hold
it keyed and they go to zero.
Any suggestions on what to look for/do?
Craig
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346751#346751
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| Subject: | Re: EGT Readings Change when Transmitting |
At 06:58 AM 7/17/2011, you wrote:
>
>Bob:
>
>I have noticed an odd thing happening on my digital EGT
>display. When I key the microphone to transmit on the Garmin SL-30,
>the graphical EGT display bars are driven down to zero. I short key
>of the mic and they go down a little....hold it keyed and they go to zero.
>
>Any suggestions on what to look for/do?
In all likelihood this is a manifestation
of poor design in EGT gauge's electro-
magnetic compatibility. Since you know
the condition exists and does not represent
a hazard to flight or even an operational
inconvenience, I'd ignore it.
Bob . . .
Message 4
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| Subject: | Re: Electrical System Drawing |
At 09:46 PM 7/16/2011, you wrote:
Attached is a draft electrical schematic based
primarily on Bob Nuckolls' Z-13 electrical system
drawing. Note that I plan on using an internally
regulated Plane Power 30A backup alternator,
which is supposed to be out by Oshkosh. If not,
I'll use the B&C SD-20. The reason for the second
7.2 AH battery is to insure field current to the
backup alternator in the event of main battery
failure. I have thought of using a second full
sized battery as the AUX, which I would connect
in parallel with the main battery for more cranking power.
Questions I have are:
Is an Avionics bus & switch unnecessary or is it
still a good idea? I like the idea, and I know
the GTX 327 is supposed to be powered off during
engine start. Also the GTN 6xx install doc says
it should be on an Avionics bus. Others have
suggested (and even said that Bob Nuckolls
doesnt think much of the idea in his book
although I couldnt find anywhere he discussed
it) that the avionics bus is unnecessary with
modern avionics, adds complexity and additional
potential points of failure. Bob doesnt show it
on the drawings Ive studied, so Im wondering.
Go to AeroElectric.com and do a search on avionics
master. The original ideas behind the birth of the
avionics master was a figment of the designer's
imagination. The enduring rationale for the AV
master is not based on physics or facts.
What are the failure modes of the EBUS Diode?
Will it ever fail open? If it fails and allows
reverse current, what is the best way to detect the failure?
They don't fail.
My schematic has a battery bus drawn, but I
really don't see a need for it. Other than a
clock and interior lights, is there something
that I have placed on another bus that really should be on a battery bus?
Do you have an electrically dependent engine?
Those items should be on a battery bus.
If you're going to have two alternators and
two batteries, suggest Z-14 instead.
What about the location of the backup alternator?
I show it connected to the essential bus instead
of the un-switched side of the battery contactor,
in the event of a dead short in the battery. I'm
not sure if that's a failure mode I need to even consider.
Another thing Ive though of is although I
havent done a load analysis yet, but Im pretty
sure with a 30A backup alternator, I could
combine the Avionics and E-Bus busses (the only
things that would be added to the E-BUS would be
Com2, Transponder and audio panel.
Any comments and criticism of the design would be greatly appreciated.
I know there are compelling notions of "doing
it a little bit better" but as your list of
questions illustrates, making changes generates
new uncertainties. The Z-figures have already
been subjected to the same questions over the
last 20+ years. By now they are 99.9% free
of unknowns.
Suggest you study Z-14 and develop a list
of questions that address and perceptions
you have of not meeting design goals for
your airplane. It's much more comfortable
to start with a proven recipe for success
and then see if serious design goals are
not being met.
If it were my airplane, I'd save a LOT of
dollars, weight and worry with Z-13/8. That
system offers overall reliability that a
King Air doesn't have. Only in the last 20
years has Z-12 found its way onto type certificated
aircraft in large quantities. The vast majority
of TC aircraft use the same architecture as
a 1946 C-140A Your concerns about failures of diodes
and batteries suggest that you're not
comfortable with the idea that reliability of
these things is very high when used with
understanding.
It's far better that you have a SIMPLE
system you understand than a NOT SO SIMPLE
system born of mis-understanding.
Bob . . .
Message 5
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| Subject: | Re: multiple shield ground wires |
At 06:32 AM 7/17/2011, you wrote:
>
>When multiple shielded wires pass through a common connector ...
>Does each shield need its own separate pin or can several shields be
>ganged together in a single pin? Shields eventually come together at
>a common ground point someplace, right?
yes
see:
http://www.aeroelectric.com/articles/pigtail/pigtail.html
Bob . . .
Message 6
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| Subject: | Re: multiple shield ground wires |
Cool! It's been a while since I read over all the neat tricks and tips.
Another simple question...
Audio wire drawings show shield ground at intercomm (real ground), but open circle
at the end-point (i.e. shield pulled back and covered with heat shrink). This
one I get.
Other schematics (ADS600B) show shield grounds at both ends of the wire. Really?
It would seem unwise to physically ground both sides, so maybe I'm not understanding
the intent.
Thanks,
Jay
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346781#346781
Message 7
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| Subject: | Re: Electrical System Drawing |
At 09:46 PM 7/16/2011, you wrote:
>Attached is a draft electrical schematic based primarily on Bob
>Nuckolls' Z-13 electrical system drawing. Note that I plan on using
>an internally regulated Plane Power 30A backup alternator, which is
>supposed to be out by Oshkosh.
Do you really NEED that much back-up power?
What are the load analysis numbers for the
minimum loads to get you to airport of intended
destination while saving the battery for
approach to landing?
>
>Another thing I've though of is although I haven't done a load
>analysis yet, but I'm pretty sure with a 30A backup alternator, I
>could combine the Avionics and E-Bus busses (the only things that
>would be added to the E-BUS would be Com2, Transponder and audio panel.
Loan analysis needs to be first . . . before
you size alternators. Also, keep in mind that
intermittent loads like landing lights, transmit
current are not continuous running loads.
Can you get your ENDURANCE loads down to 8A
or less?
If you do a search of unhappy events in the cockpit
leading to bent airplanes and/or bleeding people,
the percentage of total incidents involving electrical
system failures is exceedingly small. A majority of
those instances could have been mitigated by
better pilot understanding and good preventative
maintenance.
It's comforting to add redundancy on top of band-aid
on top of worry issue . . . but all of these have
costs of ownership. I passed a big pile of first-aid
kits in the pharmacy at Walmart last week. I think they
were $5. If Wallyworld sells them, they must move out
the door in significant numbers. I've been driving
for over 50 years, owned dozens of cars and probably had
at least a half-dozen first-aid kits of one form or another.
I can recall no single instance of ever using the contents
of such kits . . . nor finding myself in a position of
wishing I had one.
You are far more likely to enjoy a high order of
reliability by careful study of what's need should
any single device fail . . . and developing a plan-B
for that failure. The goal is not to keep everything
lit up all the time, only those things needed for
getting to airport of intended destination so that
the battery alone will get you on the ground with
lights a blazing both inside and outside the cockpit.
Every serious accident we've studied here on the list
that grew of out electrical systems issues had
root cause in poor craftsmanship and/or poor judgement
and lack of understanding of the system. Adding more
hardware will generally not do much to offset those
human frailties.
Bob . . .
Message 8
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| Subject: | Re: Circuit Design Software |
When I was in technical school and had to produce many wiring block diagrams
I used Photoshop. It was easy to make the blocks, colour them and label
connections.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: July 15, 2011 10:54 AM
Subject: RE: AeroElectric-List: Re: Circuit Design Software
<nuckolls.bob@aeroelectric.com>
At 03:38 AM 7/15/2011, you wrote:
>Another plug for MS Visio. Attached is a draft 'start circuit' I drew for
>myself a few months back. Outputing to PDF resized some of the lines, but
>Visio itself is great.
I would encourage anyone who is willing to spend the
$time$ to become competent in any sort of illustration
software also take the time to become fluent in
the language of speaking and illustrating "electronese".
If you look at any drawings produced in the 'Connection
or on aeroelectric.com, the diagrams speak to specific
connections of wires to terminals of devices, to wire
sizes, symbology to suggest type of terminals used,
internal functions of devices such as switches, relays,
contactors, motors, etc. The whole story on one page.
VERY FEW professional illustrators of consumer
product wiring diagrams bother to offer such detail
in their work-product. Even folks who should know
better. I can't tell you how many no-value hours
I spent trying to find a truly descriptive schematic
of how the fuel selector valve and gage system worked
in my '87 GMC truck. All the schematics in 'official'
published documents showed "boxes" with colored wires
routing between them and no information what so ever
as to what goes on inside the boxes. Having finally
discovered what I needed to know, it made perfect
sense and I can now draw the schematic from memory,
not as an activity to mimic somebody else's drawings
but as a fundamental understanding of how the system
works.
I'll suggest there are two aspects of creating really
useful drawings. The choice of illustration software
obviously drives the general appearance of the finished
drawings. But organization and completeness is entirely
up to the skills, willingness and experience of the
illustrator.
Symbols for lucid production of schematics and diagrams
are the language of the discipline. Learn the symbols
too and use what ever illustrative tools to present
those symbols in a manner that makes understanding
'jump off the page' into the mind of the competent
observer. These same drawings will provide a solid
foundation for sharing understanding for the not-so-
competent observer with a willingness and desire to
learn.
Just a few more little lines in the published schematics
for my truck's fuel system would have completed the
story and saved a lot of wasted time. COMPLETE
schematics are the tools of both teaching how
something works but the tools of understanding
for how to fix the thing that doesn't work at
some later time.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 9
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| Subject: | It's nice when the center holds . . . |
Funny thing is the first time I heard the term, "Dead stick landing", I knew
exactly what it meant.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of b d
Sent: July 15, 2011 6:57 PM
Subject: Re: AeroElectric-List: It's nice when the center holds . . .
The only thing I don't really understand is why you (native English
speakers) call this situation a "Dead Stick" landing, when this is
everything but a dead stick. On the contrary, this is a very "Alive stick"
situation..
What is really dead is the power source!
Excellent observation . . . . the question is, shall we go back and change
all the references using the "dead stick" phrase from all the books
references and logs or shall we allow you to get over it and accept it. One
vs. zillions :-)
As I recall in a my old conversations with the Wright Bothers it originally
meant "you are close to being dead if you don't use the stick to save your
ass". I remember asking that very same question to Orville and Wilbur while
sitting around their potbellied stove as if it was yesterday. They
reiterated that "dead" had nothing to do with the engine but more about the
pilot.
So if you were them, what phrase would you like to use if we were to correct
the whole 100 plus years of aviation history and all log books to reflect
your choice of phrases? "Alive stick"?
This reminds me of the prison story where the new guy comes in and hears
"257" and everyone laughs, then "522" and everyone laughs. He questions what
is going on and his cell mate says, "we have told these jokes so many times
we just numbered them to save time". The new guy says "let me try one . . .
257!" but nobody laughed . . . then "522" and once again nobody laughed . .
. he asked his cell mate "what gives?"
The cell mate said, "some people can tell a joke and some can't!"
You can stick with "Alive stick" and see how it works for you however
removing the word "dead" from your thoughts may not be as healthy at that
particular time. . . please let us know how it works for you. You could
just yell out "dead" and forget the stick if that confuses you. That way the
"dead" will give you some indication of what happens if you don't move the
stick in the proper, timely sequence.
Don't take it personal, I'm just having fun with you . . . Where are you
from?
Bruce
On Fri, Jul 15, 2011 at 11:55 AM, Carlos Trigo <trigo@mail.telepac.pt>
wrote:
Nice landing, and a very good demonstration of excellent pilot skills!
The only thing I don't really understand is why you (native English
speakers) call this situation a "Dead Stick" landing, when this is
everything but a dead stick. On the contrary, this is a very "Alive stick"
situation..
What is really dead is the power source!
Carlos Trigo
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-
> server@matronics.com] On Behalf Of Robert L. Nuckolls, III
> Sent: sexta-feira, 15 de Julho de 2011 18:40
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: It's nice when the center holds . . .
>
> <nuckolls.bob@aeroelectric.com>
>
> See:
>
> http://www.patricksaviation.com/videos/SUPERGT/3384/
>
>
> Bob . . .
> ////
> (o o)
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
Message 10
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| Subject: | Re: EGT Readings Change when Transmitting |
Craig,
I had an issue with my EFIS that sounds similar to yours. When I keyed the mike,
most of my readouts (vsi, heading, etc.) moved. I changed the BNC connectors
and the problem was solved. I think I did a poor job installing the original
connectors.
Not sure if this would fix your issue, but it may be worth a try.
Keith
On Jul 17, 2011, at 7:58 AM, "ChangDriver" <capav8r@gmail.com> wrote:
>
> Bob:
>
> I have noticed an odd thing happening on my digital EGT display. When I key
the microphone to transmit on the Garmin SL-30, the graphical EGT display bars
are driven down to zero. I short key of the mic and they go down a little....hold
it keyed and they go to zero.
>
> Any suggestions on what to look for/do?
>
> Craig
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=346751#346751
>
>
>
>
>
>
>
>
>
>
Message 11
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| Subject: | Over Voltage Protection for Internal Regulated Alternators |
If my IR alternator ever goes belly up I'll move to an externally regulated one,
but for now it is what it is.
I have a 40A internally regulated alternator. I am rewiring my RV-8 to Z-11 standard
and want to include OV protection. I have read up on the forums and on
AeroElectric Connection. I just want to confirm the latest thinking on OV protection.
1) use a Cb-OV-14 crowbar protection circuit on the Master switch
and
2) a S701-1 B-lead contactor
I am also installing a 60 amp ANL in the B-lead between the alternator and the
starter solenoid.
Do I understand the instructions correctly?
Thanks.
--------
John
Keller, TX
RV-8 N247TD
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346794#346794
Message 12
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| Subject: | Electrical System Drawing |
Excellent article on Avionics Master Switches. Thanks for pointing it
out.
Also for the advice to plan a system around what will happen if/when a
given
component fails. I think I've done that, but it's hard to argue with
your
point about 99.9% of the unknowns being worked out over the past 20
years.
It was this analysis that had me adding the second battery and moving
the
backup alternator to the E-Bus.
It's manufacturer statements like the one below that breeds uncertainty.
I
did look up the installation manual on the GTX 327 and it does conform
to
DO-160. Avionics Bus is history.
I have the loads for all my equipment, and know it will be well under
30A in
normal operation. I certainly don't need 30A for the E-Bus. It's just
the
flavor that PP said they were coming out with. The 20A B&C would be
more
than adequate, but I'm attracted to the PP due to its expected lower
cost
(cost to be about $600, ~$400 less that SD-20 and regulator) and its
relative simplicity (i.e. internally regulated). I probably could live
with
an 8A mushroom, but I would like the autopilot to be on the E-Bus along
with
boost pump, EFIS, & GPS/COM and I think that may be stretching things a
bit.
I've spent a LOT (much more than I care to admit) of time deciphering
z-13.
I think I understand the logic behind it, as well as the function of
each
component pretty well. That doesn't mean I understand the failure modes
of
individual electronic components, because I don't (i.e. E-Bus Diode,
Battery
Failure modes, etc.) The point you made in your book, and again in your
previous Email regarding design changes, wasn't lost on me. My
objective in
my drawing (the Avionics bus notwithstanding) was to stay true to design
objective of z-13, insure battery field current to the backup alternator
(you stated that most alternators don't run real well without a battery)
with the small battery, and design something I understood.
Thanks for your help.
Paul
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L.
Nuckolls, III
Sent: Sunday, July 17, 2011 2:55 PM
Subject: Re: AeroElectric-List: Electrical System Drawing
At 09:46 PM 7/16/2011, you wrote:
Attached is a draft electrical schematic based primarily on Bob
Nuckolls'
Z-13 electrical system drawing. Note that I plan on using an internally
regulated Plane Power 30A backup alternator, which is supposed to be out
by
Oshkosh.
Do you really NEED that much back-up power?
What are the load analysis numbers for the
minimum loads to get you to airport of intended
destination while saving the battery for
approach to landing?
Another thing I=12ve though of is although I haven=12t done a load
analysis yet,
but I=12m pretty sure with a 30A backup alternator, I could combine the
Avionics and E-Bus busses (the only things that would be added to the
E-BUS
would be Com2, Transponder and audio panel.
Loan analysis needs to be first . . . before
you size alternators. Also, keep in mind that
intermittent loads like landing lights, transmit
current are not continuous running loads.
Can you get your ENDURANCE loads down to 8A
or less?
If you do a search of unhappy events in the cockpit
leading to bent airplanes and/or bleeding people,
the percentage of total incidents involving electrical
system failures is exceedingly small. A majority of
those instances could have been mitigated by
better pilot understanding and good preventative
maintenance.
It's comforting to add redundancy on top of band-aid
on top of worry issue . . . but all of these have
costs of ownership. I passed a big pile of first-aid
kits in the pharmacy at Walmart last week. I think they
were $5. If Wallyworld sells them, they must move out
the door in significant numbers. I've been driving
for over 50 years, owned dozens of cars and probably had
at least a half-dozen first-aid kits of one form or another.
I can recall no single instance of ever using the contents
of such kits . . . nor finding myself in a position of
wishing I had one.
You are far more likely to enjoy a high order of
reliability by careful study of what's need should
any single device fail . . . and developing a plan-B
for that failure. The goal is not to keep everything
lit up all the time, only those things needed for
getting to airport of intended destination so that
the battery alone will get you on the ground with
lights a blazing both inside and outside the cockpit.
Every serious accident we've studied here on the list
that grew of out electrical systems issues had
root cause in poor craftsmanship and/or poor judgement
and lack of understanding of the system. Adding more
hardware will generally not do much to offset those
human frailties.
Bob . . .
Message 13
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Bob, just curious. What was the reason drawing Z-13/20 was omitted from
revision 12 of AEC?
Message 14
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| Subject: | Re: multiple shield ground wires |
At 12:38 PM 7/17/2011, you wrote:
>
>Cool! It's been a while since I read over all the neat tricks and tips.
>
>Another simple question...
>
>Audio wire drawings show shield ground at intercomm (real ground),
>but open circle at the end-point (i.e. shield pulled back and
>covered with heat shrink). This one I get.
>
>Other schematics (ADS600B) show shield grounds at both ends of the
>wire. Really? It would seem unwise to physically ground both sides,
>so maybe I'm not understanding the intent.
Follow the instructions. Shields can be shield-only,
attach one end; or shield+purposful conductor, attach
both ends as prescribed.
Check out extensive discussions on shields on
aeroelectric.com and in the archives of this
forum.
Bob . . .
Message 15
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| Subject: | Re: Over Voltage Protection for Internal Regulated |
Alternators
At 03:17 PM 7/17/2011, you wrote:
>
>If my IR alternator ever goes belly up I'll move to an externally
>regulated one, but for now it is what it is.
>
>I have a 40A internally regulated alternator. I am rewiring my RV-8
>to Z-11 standard and want to include OV protection. I have read up
>on the forums and on AeroElectric Connection. I just want to
>confirm the latest thinking on OV protection.
>
>1) use a Cb-OV-14 crowbar protection circuit on the Master switch
>
>and
>
>2) a S701-1 B-lead contactor
That works.
Alternatively, you can go inside the alternator
and modify it in the same manner that Plane-Power
does so that you have EXTERNAL control of the
field supply conductor while retaining use of
the internal regulator.
>I am also installing a 60 amp ANL in the B-lead between the
>alternator and the starter solenoid.
This device has nothing to do with ov protection . . .
only protection of the b-lead wire in case of shorts
in the diode array . . . a very rare event.
Bob . . .
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