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nuckolls.bob(at)aeroelect
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 Posted: Fri Oct 02, 2009 6:53 am Post subject: Basic Electrical Architecture for review... |
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At 09:57 PM 9/30/2009, you wrote:
| Quote: | Greetings all,
I've attached an electrical architecture (in Bob's drawing style)
for your review. It's for the Longeze I'm restoring. I'm doing the
restoration in multiple stages. Although it had ~1000 Hrs. on it
when I obtained it, it's been grounded since I received it. The
attached architecture is intended to be more robust and fault
tolerant than what was there (which I'm sure it is...) and certainly
not worse in that regard than a TC aircraft (though not as good as a
design with an essential bus).
Down the road a bit, I intend to replace the vacuum system and
associated instruments with electric, plus a backup alternator and
an architecture with an essential bus.
I would appreciate comments on the architecture and, specifically,
on any unmitigated faults (especially those that would not be
acceptable in a TC aircraft).
The aircraft is VFR only.
Thanks in advance,
|
You appear to have a generic distribution system
and questions that go to departures from recommendations
offered in the Z-figures.
What was it about Z-11 as depicted at:
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z11M.pdf
or features depicted in other z-figures that
prompted the changes in direction?
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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handainc(at)madisoncounty
Guest
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| Posted: Fri Oct 02, 2009 7:25 am Post subject: Basic Electrical Architecture for review... |
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Bob -
I'm a lurker on this site, but am in progress on a Pa22-20 project
(certified). How difficult would it be to use Z-11 in a certified
aircraft and get a 337 for that purpose? Has anyone done that
recently? Looks perfect for the project.
M. Haught
Robert L. Nuckolls, III wrote:
| Quote: |
<nuckolls.bob(at)aeroelectric.com>
At 09:57 PM 9/30/2009, you wrote:
> Greetings all,
>
> I've attached an electrical architecture (in Bob's drawing style) for
> your review. It's for the Longeze I'm restoring. I'm doing the
> restoration in multiple stages. Although it had ~1000 Hrs. on it
> when I obtained it, it's been grounded since I received it. The
> attached architecture is intended to be more robust and fault
> tolerant than what was there (which I'm sure it is...) and certainly
> not worse in that regard than a TC aircraft (though not as good as a
> design with an essential bus).
>
> Down the road a bit, I intend to replace the vacuum system and
> associated instruments with electric, plus a backup alternator and an
> architecture with an essential bus.
>
> I would appreciate comments on the architecture and, specifically, on
> any unmitigated faults (especially those that would not be acceptable
> in a TC aircraft).
>
> The aircraft is VFR only.
>
> Thanks in advance,
You appear to have a generic distribution system
and questions that go to departures from recommendations
offered in the Z-figures.
What was it about Z-11 as depicted at:
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z11M.pdf
or features depicted in other z-figures that
prompted the changes in direction?
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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handainc(at)madisoncounty
Guest
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| Posted: Sat Oct 03, 2009 1:53 pm Post subject: Basic Electrical Architecture for review... |
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Bob - Sent this earlier but did not get a reply. Thought I would send
it again.
M. Haught
Bob -
I'm a lurker on this site, but am in progress on a Pa22-20 project
(certified). How difficult would it be to use Z-11 in a certified
aircraft and get a 337 for that purpose? Has anyone done that
recently? Looks perfect for the project.
M. Haught
Robert L. Nuckolls, III wrote:
| Quote: |
<nuckolls.bob(at)aeroelectric.com>
At 09:57 PM 9/30/2009, you wrote:
> Greetings all,
>
> I've attached an electrical architecture (in Bob's drawing style) for
> your review. It's for the Longeze I'm restoring. I'm doing the
> restoration in multiple stages. Although it had ~1000 Hrs. on it
> when I obtained it, it's been grounded since I received it. The
> attached architecture is intended to be more robust and fault
> tolerant than what was there (which I'm sure it is...) and certainly
> not worse in that regard than a TC aircraft (though not as good as a
> design with an essential bus).
>
> Down the road a bit, I intend to replace the vacuum system and
> associated instruments with electric, plus a backup alternator and an
> architecture with an essential bus.
>
> I would appreciate comments on the architecture and, specifically, on
> any unmitigated faults (especially those that would not be acceptable
> in a TC aircraft).
>
> The aircraft is VFR only.
>
> Thanks in advance,
You appear to have a generic distribution system
and questions that go to departures from recommendations
offered in the Z-figures.
What was it about Z-11 as depicted at:
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z11M.pdf
or features depicted in other z-figures that
prompted the changes in direction?
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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steve(at)tomasara.com
Guest
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| Posted: Sun Oct 04, 2009 8:31 am Post subject: Basic Electrical Architecture for review... |
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Hi Bob,
Thanks for taking a look at my architecture drawing. As to why it
differs from the recommendations in the Z-figures. Good question. I
hope my answers are as good (I have no inherent desire to be "different").
The project at hand is the "repair" of a LongEZ that already has 1000
hrs on it by the previous owners (mostly by the original builder). My
objective is to return the aircraft to what I consider flight-worthy
shape. "Return" might not be the right word here as there were many
details (electrical and otherwise) on the aircraft that have never been
in what I would consider (by my standards today) flight worthy, though
they may have been by some standards 30 years ago... And then put a
year or two of flying on it (day VFR) while I become opinionated about
what I want in it and what I don't. Then, the next project will be to
add the enhancements I think are appropriate. I'm expecting the desired
enhancements to include night & IFR support, eliminate the vacuum system
etc.
This project description flows down to the electrical subsystem as the
constraint to keep it as simple as possible to meet the objective (and,
specifically, avoid the temptation to grow the scope of the project).
One other bit of background that may be relevant to my particular
choices: Almost all of my flying since my license (1988) is in my
no-electrical system Taylorcraft. For day VFR missions, a total
electrical system failure, as long as the failure didn't make fire or
smoke, would not give me sweaty palms. I would, however, be mindful of
the loss of ignition redundancy and might choose to shorten the leg...
Note: All of my explanations below (many), are intended solely as
explanation and not a "defense". Although I believe I have thought
everything through, I might have missed stuff and I could easily have
misunderstood why some things were the way they were. PLEASE feel free
to express any disagreement. I am seeking out things that I still need
to fix.
Given the above, this is what I did relative to Z11 and why:
- Removed the starter and associated support. (As I also removed it
from the aircraft. I saved the parts as I might want to reinstall it
(more appropriately wired) later.
- Removed the primer (As I also removed it from the aircraft. This
might also be added back later in a more appropriately wired and plumbed
manner)
- Replaced the ignition switches with SPST as part of the removal of the
starter support features. If/when I re-install the starter I intend to
revisit the latest recommendations regarding connections here and
anticipate I will be replacing these with the progress transfers as
shown in Z11.
- Rearranged the ground buses to match a pusher configuration rather
than the tractor configuration.
- Redefined the avionics ground bus to be an audio ground bus. My
Nav/Com uses a differential audio path allowing separate audio/power
grounds. All the avionics power grounds, with the exception of the
low-power intercom return, terminate at the PNL Gnd bus. All audio
grounds (including the intercom power ground) terminate at the Audio Gnd
bus.
- Reduced the number of connections tying the PNL ground to the Audio
ground as it no longer carries any significant current.
- Replaced the regulator shown on Z11 with the one existent on the aircraft.
- Added a stand alone low-voltage indicator as the existent regulator
(to my knowledge) does not support the feature.
- Replaced the ANL with one sized to the existent alternator.
- Replaced the shunt with one sized to match the existent Ampmeter.
- Used a 20Amp blade fuse instead of a fuse-link for the regulator power
for reasons that are lost to history. I will be using the fuse-link
rather than 20A fuse approach. (I suspect that, back when I did this,
the recommendation for a fuse-link wasn't as obvious but who knows...
My book is years old.)
- Combined the endurance bus and main battery bus as the only items on
the main bus that have significant load are the position, landing, and
strobe lights and, if I end up with a (currently not shown) backup path
for the bus feed, the check list will list specific loads to drop (e.g.
turn off these lights) before enabling the backup power path.
- Removed the bus alternate feed as I haven't (yet) justified it as a
worthy exception to the project guidelines (repair, not enhance as this
stage).
- Removed the Battery Bus as I have nothing that would attach to it.
- Adjusted wire gauges as seemed appropriate for my actual loads.
- I put each engine instrument on it's own fuse as I couldn't think of a
good enough reason not to. It would have been the only exception to the
one-fuse-per-end device approach.
- I changed the "6 inches or less" to "24 inches or less" (turns out to
be about 18 inches at the longest) due to the LongEZ's configuration
constraints. The battery is in the nose. The contactor, shunt and ANL
current limiter (with the regulator mounted on the closest fuselage
side) are all mounted on the canard bulkhead (about as close as you can
get them to the battery but the required wire length is still longer
than 6 inches) and the fuse panel is on the right fuselage side between
the canard bulkhead and the panel. This is also about as close as you
can get it but is still requires wire lengths longer than 6 inches.
Fortunately, with a non-metal airframe, it's a little easier to ensure
appropriate protection for these runs.
- I changed the fuse values to match either that recommended by the
manufacturer of the end device, or, if not stated, to an appropriate
value less than or equal to that required to protect the wire.
Let me know if I missed any changes.
It occurs to me now that the cleanest way to add an alternate power path
(I don't like the approach I pondered on the schematic) may be to
(conceptually, relative to Z11) move everything except the regulator
power path from the main bus to the endurance bus (thus the main bus
effectively becomes the output contact on the contactor). And then
replace the battery bus and the alternate feed switch with a fuse-link
to a panel mounted breaker switch. (Ideally a fuse link appropriate for
7-10 Amps, assuming such a thing exists) My justification for the
breaker switch in this application that I want this resettable in flight
given that I will be required to manually load shed (i.e. turn off the
lights) and, if I neglect the check list and leave the lights on, I want
to have a reasonable recovery option.
I'm also still seriously considering leaving the alternate feed path off
until I revisit the electrical system during the "enhancement" project
to follow in a couple of years. For my current project, I think the
alternate feeds greatest value is, in the event of a contactor failure,
allowing my to keep my redundant source of ignition (but it also allows
me to keep my primary nav/com etc. which is also nice 
All comments welcome but I am particularly interested in discussion of
failure mode for which I don't have appropriate fault tolerance.
Thanks in advance,
Steve Stearns
Boulder/Longmont, Colorado
CSA,EAA,IAC,AOPA,PE,ARRL,BARC (but ignorant none-the-less)
Restoring (since 1/07): N45FC O235 Longeze Cothern/Friling CF1 (~1000 Hrs)
Flying (since 9/86): N43732 A65 Taylorcraft BC12D
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Oct 05, 2009 11:24 am Post subject: Basic Electrical Architecture for review... |
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At 10:43 AM 10/5/2009, you wrote:
| Quote: | Bob and the group:
>**
In case you were interested in following up, I've attached my
detailed schematics.
|
I printed out your set of drawings on nice big
11 x 17 sheets with every intention of doing
a well considered review . . . but hit the
brick wall with the interstate/county road/
cow-path wiring diagram. These are exceedingly
difficult to read for useful operational and
FMEA information. The drawings for Cessna,
Beechcraft, King Radio, AND the 'Connection
were done that way for good reasons.
Sorry I can't be of more service . . .
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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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Oct 05, 2009 11:24 am Post subject: Basic Electrical Architecture for review... |
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| Quote: | >*
Hmmm, Given your suggestion above, I'm now considering using a
fuse-link from the always hot side of the contactor (my current
"battery bus" such as it is...) to the electronic ignition. This
leads to an interesting dilemma. The manual for my electronic
ignition calls out a 15A fuse protecting 18AWG wire. I presume the
seemingly excess fuse size is to provide headroom for surge or pulse
current. IF that is the case, I would think a fuse-link
appropriately sized for 18AWG wire (i.e. 22AWG) would be appropriate
protection (and better than a 15A fuse).
Your thoughts?
|
Let's not scatter fusible links around for any
applications other than the slots suggested in
the z-figures. How much current does your electronic
ignition really draw? I'd be amazed if it were greater
than 3A under worst case conditions. 3A is a TON
of ignition energy.
| Quote: | I like the idea of keeping redundant sources of ignition if I have a
contactor failure.
|
You have a magneto. That's your redundant ignition.
The goal now is to supply a max-reliabilty, never
turned off supply for the electronic system. The
battery bus is the most stable, all-conditions source
of electrical energy.
| Quote: | However, if I decide to also put the fuel pump on the battery
bus, then I could either use another fuse-link for it (a 24AWG link
seems appropriate) off the always hot side of the contactor or
actually use a real fuse block battery bus for both the elec.
ignition and fuel pump.
|
No, ordinary fuses are just fine.
| Quote: | I could just put in the alternate feed path to the endurance bus
(which, in my case, is the only bus with manual load shedding). It
seems like I could use the 16AWG fuse-link (as on Z12) as the
protection for the (proposed by me) panel-mounted switch/breaker for
the alternate feed.
|
Why not wire it per the Z-figures?
| Quote: | Given that I haven't yet re-read chapter 17 or refreshed my load
analysis, this may change. But as of now, I think the approach that
best meets current objectives is to use fuse-links for the elect.
ignition and possibly the fuel pump (not sure how I feel about the
fuel pump switch being hot when the master switch is off.
|
If your magneto switch is left ON after the battery
is OFF, it's hot too. This is what check lists are
for.
Keep in mind that the z-figures are, in some cases,
20+ years old. They've been combed and sifted for
"gotchas" while optimizing the failure mode effects
analysis with the minimum parts count.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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steve(at)tomasara.com
Guest
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| Posted: Tue Oct 06, 2009 5:53 am Post subject: Basic Electrical Architecture for review... |
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Bob said:
| Quote: | **These are exceedingly difficult to read**
Surprisingly enough, they work well for me but then they are much closer
|
to what I'm used to than the book format. I appreciate your efforts
none-the-less. I'll reformat extracts into your preferred format (as I
did with the "architecture drawing") when offering things for you and
the group to review in the future.
Steve Stearns
Boulder/Longmont, Colorado
CSA,EAA,IAC,AOPA,PE,ARRL,BARC (but ignorant none-the-less)
Restoring (since 1/07): N45FC O235 Longeze Cothern/Friling CF1 (~1000 Hrs)
Flying (since 9/86): N43732 A65 Taylorcraft BC12D
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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