Today's Message Index:
----------------------
1. 06:05 AM - Re: Z-12 current sensor options (Bill Boyd)
2. 08:07 AM - Re: Re: Is an ATC/ATO Fuse Block a Realistic Single Pt. of Failure? (Robert L. Nuckolls, III)
3. 08:14 AM - Re: Z11 revision needed? (Robert L. Nuckolls, III)
4. 12:35 PM - Re: Is an ATC/ATO Fuse Block a Realistic Single Pt. of Failure (johnbright)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Z-12 current sensor options |
Thanks again, Bob. When it's all dialed in, I'm going to sketch my
personal iteration of Z-12 and post a snap here on the List for critical
review.
-Bill
On Wed, Jan 22, 2020 at 6:52 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 05:28 PM 1/22/2020, you wrote:
>
> Yes, that is correct, planning both B leads to the anti-battery end of th
e
> physical brass-bar shunt Dynon shunt.=C3=82 I thought it would work that
way
> but nice to have your eyes on it first.=C3=82 Thank you.=C3=82 I'll hav
e them leave
> the Hall sensor out of the panel quote.=C3=82
>
>
> Works good . . . lasts a long time . . . sounds like a PLAN . . .
>
>
> Bob . . .
>
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Is an ATC/ATO Fuse Block a Realistic Single |
Pt. of Failure?
At 09:06 PM 1/22/2020, you wrote:
><john_s_bright@yahoo.com>
>
>Hi Mark,
>
>In case this works for you... add a 2nd feed stud to the Bussman
>fuse block... https://photos.app.goo.gl/ZKjbqnU3DfkUKNex2
Be circumspect about redundant feed paths to critical
loads . . . how will you know that one of htem is
not intact? The value of a dual feed path is
lost if integrity of each is not at least
pre-flight detectable or annunciated in
flight.
Bob . . .
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Z11 revision needed? |
At 06:56 PM 1/22/2020, you wrote:
><ceengland7@gmail.com>
>
>Hi,
>
>I'm in-process, updating my purchased RV6 electrical system. It was
>loosely based on the AEC Z figures, but needs updating for several
>reasons. This is a relatively simple, 1 battery/1 alternator system
>with 1 mag & 1 Lightspeed ignition, and Bendix style injection.
>
>While consulting the Z figures to rearrange loads to various buses,
>I noticed the boost pump feed on the Endurance bus is shown as 3A.
>No doubt Z11 was created when 'simple' planes had fueled delivered
>by carbs, but Bendix style injection has become quite common on RVs
>& other Lyc powered homebuilts.
The z-figures are ARCHITECTURE EXAMPLES to
aid in fabrication of a power distribution
appropriate to YOUR project.
>The issue I'm raising is that virtually all the commonly used
>'boost' pumps (actually *backup* pumps) in use with Bendix style
>fuel injection these days have at their core, an automotive fuel
>injection pump which draws a minimum of roughly 6A continuous, with
>no doubt, considerably higher startup inrush current. With only a 7A
>fuse (and 16 Ga wire) feeding the Endurance bus, This seems quite
>marginal. Even if we assume minimal actual loads from the other
>active devices on this bus, the need to activate the backup fuel
>pump could result in getting 'close to the edge' of voltage drop
>ratings for 16 Ga wire, and if we are already operating in Endurance
>mode, could easily take out the 7A fuse supplying the endurance feed
>to the bus.
This is what the LOAD ANALYSIS is for . . . it
should be the very first document you craft in
the planning for your airplane. This document
provides the foundation for ADAPTING a z-figure
to your specific needs.
>Should wire sizes and fusing be increased on this drawing, as has
>been done on some of the other drawings where the backup pump load
>is shown as 10A?
>
>I should note that several other Z figures also show 7A protection
>and 16 Ga wire to the Endurance bus, but most of the others don't
>define any loads on that bus. Assuming that a high pressure pump is
>needed in the a/c, it would need to be on the Endurance bus and, it
>seems to me, the bus would need a more robust supply.
>
>Even with everything (including the alternator) on line, having to
>add the backup fuel pump load to the other loads on that bus will
>push voltage drop on the feed wire past the typical 10% limit.
Size ALL circuit protection to the anticipated
loads along with considerations for the use
of fuses that need 25 percent headroom for
steady loads . . . EXTRA for loads with inrush
currents. Fuses can be 'hammered' to failure
by seemingly ordinary circumstances.
Fuses are first sized to wire then upsized to
grunt transients. This consideration is above an
beyond any decisions about architecture. What
your involved in now is the first phase
of failure mode effects analysis based on a
knowledge of system components.
Good on you my friend.
Bob . . .
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Is an ATC/ATO Fuse Block a Realistic Single Pt. |
of Failure
Thanks Bob,
I do understand, as importantly shown in the N811HB accident investigation, that failures that have no effect on the current flight should be detected before the next flight! Those unfamiliar with N811HB may well learn more than one lesson at http://www.aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/
I am planning an O-360 with dual SDS ignition and injection. Part of my approach
is to develop a detailed schematic of what it takes to keep the engine running,
have a radio, and have a "six pack" of instruments long enough to make an
alternate airport with the main contactors open (Z-14 derivative). I plan an engine
bus with dual feeds, one from each battery via Schottky diodes; loss of
one feed is preflight detectable using EFIS voltmeters.
I do a wire by wire failure analysis that informs the preflight checklist:
Assume only one failure per flight.
What are the effects of a wire shorted or open?
Does the failure affect safety? If so, can the safety effect be designed out?
How will the failure be discovered before the next flight?
If the failure affects flight safety, can something be done about it?
How will the crew know what to do? Can they do it immediately by simple predetermined
actions?
In case of electrical fire can the battery contactor(s) be opened without affecting
flight safety?
Some failures not detectable by preflight checks are added to annual inspection:
A fat wire short to sheetmetal that clears itself.
Redundant grounds for both the computer and the injector driver sections of the
ECUs. (Loss of computer ground sends injectors and coils 100% duty cycle.)
Redundant grounds to voltage regulators.
Some check done twice yearly:
Ship's batteries and EFIS backup batteries capacity checks.
Primary and aux alternator crowbar test.
--------
John Bright, RV-6A, at FWF, O-360, dual SDSEFI EM-5-F
<a href="https://drive.google.com/drive/folders/1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K">Dual
Batt Dual Alt RV-6A SDS dual EM-5-F</a>
john_s_bright@yahoo.com, Newport News, Va
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=494425#494425
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|