Today's Message Index:
----------------------
1. 06:51 AM - (Rino)
2. 06:52 AM - Issue with Garmin GTX 330 XPDR ()
3. 09:11 AM - Re: AeroElectric-List Digest: 17 Msgs - 01/01/10 (speedy11@aol.com)
4. 09:13 AM - Questions about circuit protection ()
5. 09:25 AM - Re: Questions about circuit protection (speedy11@aol.com)
6. 09:43 AM - Re: Noise filter ? (Robert L. Nuckolls, III)
7. 10:09 AM - Re: Questions about circuit protection. (Robert L. Nuckolls, III)
8. 10:11 AM - Re: THE VIRTUE OF SIMPLICITY (Ralph & Maria Finch)
9. 10:14 AM - Re: Re: AeroElectric-List Digest: 17 Msgs - 01/01/10 (Robert L. Nuckolls, III)
10. 11:09 AM - Re: Questions about circuit protection (Matthew Schumacher)
11. 11:12 AM - Re: Questions about circuit protection. (Matthew Schumacher)
12. 11:12 AM - Re: Adding an antenna to improve on the ground reception? (jim-bean@att.net)
13. 12:44 PM - Simplicity and circuit protection (Richard Girard)
14. 01:02 PM - Re: Questions about circuit protection. (Tim Andres)
15. 01:13 PM - Re: Simplicity and circuit protection (B Tomm)
16. 02:14 PM - Re: Simplicity and circuit protection (Richard Girard)
17. 05:19 PM - Re: Simplicity and circuit protection (mmayfield)
18. 07:10 PM - Z-14 Switch Combos (Perry, Phil)
19. 07:43 PM - Re: Simplicity and circuit protection (B Tomm)
20. 08:08 PM - Re: Re: Simplicity and circuit protection (Tim Olson)
21. 10:38 PM - Re: Questions about circuit protection (Robert L. Nuckolls, III)
Message 1
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Ton voyage s'est bien pass=E9?
Tout =E9tait correct =E0 ton appart?
Bises, Rita
Message 2
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| Subject: | Issue with Garmin GTX 330 XPDR |
1/2/2010
Hello Don Morrisey, You wrote: "I later discovered that each time I activate
the Master SWitch the unit turns itself on even though I had left it powered
off via the "Off" button on the unit. I went back over the wiring and
nothing seems amiss??? Any idea why it would be doing this?"
This very topic is currently being discussed on the aeroelectric list. Read
the email exchanges below (last email is first).
Also if you go to this web site, download the GTX327 installation manual and
look at figure B4 on page 47 you will see the pins and notes that are being
discussed.
http://www.velocityxl.com/Downloads/GTX327Transponder_InstallationManual.pdf
OC
==========================================
Allen then wrote:
Actually I meant 327 rather than 337. I looked at the installation manual
pin out diagram and my Approach Systems engineer (Tim Hass) has pin 1 and
pin 15 jumpered. The drawing calls pin 1 "Avionics Master on which may be
the pin that I could unhook from power and make it work like we want.
I emailed Tim Hass at Approach Systems to ask for clarification on this
issue. I'll let you know what I find out.
Allen
=================================================
-----Original Message-----
From: bakerocb@cox.net [mailto:bakerocb@cox.net]
Sent: Friday, January 01, 2010 1:22 PM
Subject: GTX337 ON or OFF?
1/1/2010
Hello Allen Fullmer, You wrote:
"........skip.....I have also noticed that the GTX337 transponder cannot be
set to remain off when power is supplied. It will remain in the standby
position but, once again, when I am playing and fiddling around I just hate
to see it go up and down unnecessarily. Haven't decided on a switch for it
or not."
I also can not program my GTX327 to remain OFF when power is applied or
reapplied to the avionics buss.** But the GTX327 has some options on which
pins electrical power can be supplied to. If you pick the correct pin(s) the
box will remain OFF until you push the ON button on the face of the box.
I suspect that the GTX337 may be built the same way. So if you desire, and
have the capability, you could rewire your GTX337 so that it would remain
OFF until you pushed the ON button on the face of the box.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
**PS: I suspect that the person who wired my panel set it up that way so
that it would take a very deliberate OFF button action on my part in order
to take off with the transponder OFF. I am with you, I'd like to have total
ON - OFF control of the box with the buttons on the face of the box.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
==============================================
Time: 05:54:51 PM PST US
From: Don Morrisey <donmorrisey@hotmail.com>
Subject: Avionics-List: Issue with Garmin GTX 330 XPDR
Hello Listers
I have just been finishing up my panel and one of the last things in was my
transponder a Garmin GTX 330 . Very straightforward to install as I had a
wiring harness made for it. Anyway got it in and it powered right up and
does a self test etc. I later discovered that each time I activate the Ma
ster SWitch=2C the unit turns itself on=2C even though I had left it powere
d off via the "Off" button on the unit. I went back over the wiring and no
thing seems amiss???
Any idea why it would be doing this? I have no issues with any of my other
avionics that are connected to this wiring harness (SL40 and PMA 4000 Audi
o Panel).
Thanks. Don...
www.donsbushcaddy.com
Don Morrisey's Skunkworks
Message 3
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| Subject: | Re: AeroElectric-List Digest: 17 Msgs - 01/01/10 |
Jerry,
All interesting information.
But, your assumption is that you are the only safety conscious one on the
forum and the rest of us are idiots. That simply is not the case. (If you
doubt this comment, then refer to your comments below "I have a plan" and
"overly complicated equipment and redundant backup systems, much of which
you barely understand.")
I wonder - why you think the rest of us are stupid?
You said, "What concerns me is that all the emergency procedures required
to take advantage of redundant systems must be committed to writing and to
memory;
then must be tested, practiced and periodically rehearsed." Why are you
concerned? Do you fear that adding electric flaps instead of manual flaps
adds complication? Using a flap example may seem like an invalid argument
to you, but 40 years ago many were saying exactly what you are saying today
about adding "too much complication" to the cockpit. Manual is better was
the claim. In many ways it was. I prefer manual flaps even today. But
the reality is that electric (or hydraulic - talk about complicated) flaps
are the norm today. And appropriate emergency procedures are established for
the "upgrade" to electricity. And suppose the electric (hydraulic) flaps
don't work? You land anyway!
What about electric starters? Lots of complications and emergency
procedures added as a result of adding starters to airplanes. Propping is the
way
to go. Well ... except for that TIO-540. Well a TIO-540 is too
complicated anyway - leave it off. Too many emergency procedures.
I agree with you that any component added to the airframe complicates
operations and emergencies somewhat - and adds weight. I do not agree with
your admonishment of other builders that they are too ignorant to add such
complication or redundancy. Other builders (myself excepted) undoubtedly have
approximately the same level of "smarts" as you and they know to establish,
verify, and practice emergency procedures for installed equipment.
I hate it when "I know better than you" type people espouse their
admonishments on the forum. We are building experimental aircraft. We are going
to experiment. We may make good improvements for aviation. We will, by
necessity, devise new emergency procedures to accommodate the improvements.
We do plan for and practice the emergency procedures. And ... we are not
stupid.
BTW, have you ever started one of Ford's Model A's? Talk about
complicated! I'll take the convenience of today's "complicated", computer-overloaded
autos.
Regards,
Stan Sutterfield
Do Not Archive
Parts left out cost nothing and cause no service problems. Parts left out
also
can cause no emergencies or smoke in the cockpit. I believe that the
first statement
was attributed to GMs Charles Boss Kettering. Henry Ford was a great
advocate of the value of simplicity too; whether it be in life, in work or
in
play. If our missions often involve flying IFR at night, then a very good
case
can be made for all the backups, added equipment and redundancy advocated
in
this forum. What concerns me is that all the emergency procedures required
to take advantage of redundant systems must be committed to writing and to
memory;
then must be tested, practiced and periodically rehearsed. With the
increased
costs of flying, TRUE currency becomes even more elusive. During an
emergency,
pilots rarely have time to look in their POH for emergency procedures;
you will not have time either. When the adrenalin and sweat is flowing
and when
fear and tunnel vision sets in is not the time to begin learning emergency
procedures.
What is your plan to counter smoke in the cockpit? I have a plan. The
FAA is
currently saying that you need one too.
If 99% of your planned missions are day VFR, think twice or 3 times,
before going
overboard on adding overly complicated equipment and redundant backup
systems,
much of which you barely understand. And dont forget that your airplane
will
perform better with less weight.
--------
Jerry King
Message 4
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| Subject: | Questions about circuit protection |
1/2/2010
Hello Matthew Schumacher, You wrote: "I think I will just get fuse blocks
per your recommendation for the reasons you mention, but also because
problems with a fuse can be remedied in the air quickly and easily."
If you are thinking of replacing fuses in the air to trouble shoot and solve
an electrical problem please think again. There are several disadvantages.
Some are:
1) Your airplane's Operating Limitations (part of its airworthiness
certificate) will require you to equip the aircraft in accordance with 14
CFR 91.205 if you fly at night or IFR.
Paragraph 91.205 (c) (6) says: "One spare set of fuses, or three spare fuses
of each kind required, that are accessible to the pilot in flight."
This means that, by regulation, if you design your airplane so that you have
access to those fuse blocks in flight then you must also have available to
you all those spare fuses while in flight. Do you want to create that burden
/ nuisance / danger?
2) Trouble shooting an electrical system in flight by fumbling around to
locate and then insert the appropriate fuse is not a good idea, particularly
at night or IFR when you should be concentrating on flying the airplane.
So fuse blocks are a good idea, but where you locate them has some
operational and safety implications. Please read some more of Bob Nuckolls'
philosophy regarding electrical problems / failures in flight.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
========================================================
Time: 07:42:35 PM PST US
From: Matthew Schumacher <schu@schu.net>
Subject: Re: AeroElectric-List: Questions about circuit protection.
First, thank you very much for looking at my stuff Bob. I greatly
appreciate it and have donated to keep this list going...
...................................... big skip
......................................
I know that fuses/breakers/fuselinks protect the wiring, what I was
missing was the part about problems with one component spreading to
others instead of being isolated. I think I will just get fuse blocks
per your recommendation for the reasons you mention, but also because
problems with a fuse can be remedied in the air quickly and easily.
Thanks again,
schu
Message 5
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| Subject: | Re: Questions about circuit protection |
Often times we get admonishments on this forum to not do something and our
questions are never answered. While the admonishment is fine (and
welcomed) when coming from someone so educated in electricity as Bob, getting
the
questions answered is the desire.
Yes, you can bundle some of the lighting on a single breaker - realizing
that the breaker and wires need to be sized accordingly for the load. Bob's
advice is to consider using fuses. You can have a fuse for each light for
a fraction of the cost in weight and money as the breaker. Personally, I
chose breakers for my airplane.
Personally I would not use a single breaker for the E-bus and omit breakers
for individual devices on the bus. Again you would have to size the
breaker for the entire load and wiring would have to match. In my opinion, not
a logical approach. Bob's argument for fuses should again be considered.
As far as fuselinks, I don't understand them either. I haven't studied
them because I had no application for them.
Regards,
Stan Sutterfield
Do not archive
Can I group up some of the lighting on a
single breaker? Also, what about using a breaker for the entire e-bus
then omitting the breakers for the devices on the ebus? The lines will
be real short and it eliminates the single point of failure (breaker.)
Also, what about fuselinks? I understand them to be like a fuse that
blows extremely slowly, but I'm not fully understanding when and where
to use them.
Message 6
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| Subject: | Re: Noise filter ? |
>However, my second radio is on my main bus. Should I stick a diode
>and capacitor in its feed line after the fuse ? Or should I plan
>instead to rectifiy any noise issues if I actually have them ? My
>anti-collision lights will be LEDs, not strobes, but I tend to think
>clean power is good power.
Jeff, I wouldn't strike out to solve a "noise" problem
that has yet to manifest itself. Many moons ago a builder
called me one night to describe how he had shielded the
majority of his system's wiring, put off the shelf filters
on all potential victims and antagonists and was calling
to ask, "is there anything I've overlooked?"
I had to ask, "Gee, how does your noise problem manifest
itself?"
"Oh," he replies, "I'm still building. The airplane hasn't
flown yet."
This is a tip-of-the-bell-curve example of how NOT
to approach the design and fabrication of a new system
in an airplane.
Keep in mind that the majority of antagonist/victim
accessories are DESIGNED with their target application
in mind. We consider DO-160 EMC and MIL-STD-704 power
studies that teach us how to LIVE with a certain amount
of noise on the bus while LIMITING how much noise
we allow to be generated on the bus.
I've seen dozens of products offered like the ubiquitous
"surge protection" devices for computers . . . except
these are intended to ward off evil spirits and slay
dragons that are reputed to live on your airplane's
power system.
I think I spoke about extra-ordinary prophylactic
noise mitigation in the chapter on noise in the
'Connection. Once you've shielded p-leads and
crafted single point grounds, your probability
of noise problems goes down to a tiny fraction of
what's possible.
The guy who called me about his noise mitigation
program expended many hours, dollars and several
pounds of empty weight on a useless activity.
I can tell you that tens of thousands of strobe
systems (and other potentially noisy appliances)
have been successfully integrated into both TC
and OBAM aircraft with no noise dragons to slay.
Put the stuff all together first using ground
rules established by decades of lessons-learned
and let's tackle a noise problem later. It's
likely that it won't show up.
Bob . . .
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 7
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| Subject: | Re: Questions about circuit protection. |
> >
> > Why not simply add a switch in series with your
> > e-bus normal feed path diode and label it
> > "Avionics Master". Then ditch the avionics bus
> > and run your avionics of concern along with
> > endurance necessities from the e-bus.
>
>It is my understanding that the purpose of the e-bus is to be able to
>open the battery contactor and instantly have the system load drop to
>whatever is on the e-bus making it easier and quicker for the pilot to
>shed unneeded load in the event of an alternator failure.
No. The E-bus is where you power things that are
part of your Plan-B for sustained flight battery
only. YOU decide what the E-hours are. If you plan
to maintain the battery such that E-power-hours
is equal to or less than battery capacity, great.
If some smaller performance value meets your design
goals, great. But DECIDE what those design goals
are and craft the system to match.
>To that end I put only required avionics on the e-bus and avionics that
>I don't absolutely need to have on an avionics bus thinking that this
>was in line with the design goals of using an e-bus.
Since you have subscribed to the ill-conceived notion
of an 'avionics bus' then the simple solution is
to COMBINED the functionality of the A-bus
with the E-Bus and add the switch in series with
the normal feedpath diode. You don't need to add
a special bus to coddle radios that don't need
coddling.
>So my question is this: Given that simple is always
>cheaper/lighter/more reliable, is it worth the weight/cost/complexity to
>add a bus and a switch so that I can keep my avionics off during start,
>and be able to instantly shed all non-critical loads? I thought it was,
>but it seems like you disagree.
As described above, the only increase in complexity
to meet your design goals for an A-bus is make the
E-bus double up in that capacity. Alternatively,
you can abandon the legacy prophylactic for an
A-bus and associated master switch. See:
>Also, what are others doing here? Are they simply using the built in
>power switch to turn stuff off at start (if the component has a built in
>switch.)
The avionics master switch was never really necessary
for the reasons imagined at the time it was created.
I remember. I was working as a tech writer at Cessna
when the AV master was conceived. I wrote sections
of maintenance manuals that spoke to the perceived hoards
of hazard lurked upon the bus waiting to pounce on
fragile radios.
See:
http://www.aeroelectric.com/articles/avmaster.pdf
http://www.aeroelectric.com/articles/spike.pdf
http://www.aeroelectric.com/articles/Philosophy/Whats_all_this_DO160_Stuff_Anyhow.pdf
Today, we know better. There's no value to be added
by dedicating a specially protected bus to power
radios.
>I know that fuses/breakers/fuselinks protect the wiring, what I was
>missing was the part about problems with one component spreading to
>others instead of being isolated. I think I will just get fuse blocks
>per your recommendation for the reasons you mention, but also because
>problems with a fuse can be remedied in the air quickly and easily.
As Bob suggested in his earlier post, you might
like to review the philosophy of breakers vs.
fuses and the value of crafting a system where
there are no designed in nuisance trips of
fuses and no single accessory is "critical"
. . . i.e. a failure tolerant system
Fuse blocks can be tucked away out of sight,
out of reach and out of mind. You need only
ONE breaker and that only if you're using
crowbar ov protection. Otherwise, it can ALL
be out of reach fuses.
Bob . . .
Message 8
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| Subject: | THE VIRTUE OF SIMPLICITY |
To play the part of the loyal opposition:
Yes, but.
Do any of us really want to depend on one of the old cars for daily transportation?
I have memories, almost all bad, of the old clunkers. I love my modern autos,
turn the switch and they start and run. Oil changes at greatly increased
intervals, hardly any "tune-ups" and such.
Our lives would be simpler without building airplanes, dealing with computers,
and so forth. But by definition those reading this are doing those things and
other non-simple chores and hobbies.
To airplanes. Day VFR implies no lights, even no radios. Stay out of Class B and
no transponder required. My build is delayed considerably by adding lights
and such but I want them. I'll also have an EFIS and autopilot because I think
they nice and a good convenience.
These are, after all, experimental. Experiment as you wish. Let's just be aware
of all the costs of adding equipment.
BTW, I'm flying an Aircoupe now. When my RV-9A is finished I don't think I'll
notice a few extra pounds in comparison...and besides, most of us Americans could
easily make up for added equipment weight by losing our spare tires ;-)
Ralph Finch
Davis, California
RV-9A QB-SA
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of racerjerry
Sent: Friday, January 01, 2010 12:21 PM
THE VIRTUE OF SIMPLICITY
__________ Information from ESET Smart Security, version of virus signature database
4735 (20100101) __________
The message was checked by ESET Smart Security.
Message 9
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| Subject: | Re: AeroElectric-List Digest: 17 Msgs - 01/01/10 |
At 11:07 AM 1/2/2010, you wrote:
>Jerry,
>All interesting information.
>But, your assumption is that you are the only safety conscious one
>on the forum and the rest of us are idiots. That simply is not the
>case. (If you doubt this comment, then refer to your comments below
>"I have a plan" and "overly complicated equipment and redundant
>backup systems, much of which you barely understand.")
>I wonder - why you think the rest of us are stupid?
<snip>
Gently my friend. Why do you take this as a
personal attack? This is a forum for the exchange
of ideas, crafting elegant design goals and the
perfection of recipes for success.
Please speak to ideas in the light of what I
cited above. There's no reason for or value
in pitching cabbages, tomatoes or rocks at
each other.
Bob . . .
Message 10
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| Subject: | Re: Questions about circuit protection |
bakerocb@cox.net wrote:
> If you are thinking of replacing fuses in the air to trouble shoot and
> solve an electrical problem please think again. There are several
> disadvantages. Some are:
>
> 1) Your airplane's Operating Limitations (part of its airworthiness
> certificate) will require you to equip the aircraft in accordance with
> 14 CFR 91.205 if you fly at night or IFR.
>
> Paragraph 91.205 (c) (6) says: "One spare set of fuses, or three spare
> fuses of each kind required, that are accessible to the pilot in flight."
>
> This means that, by regulation, if you design your airplane so that you
> have access to those fuse blocks in flight then you must also have
> available to you all those spare fuses while in flight. Do you want to
> create that burden / nuisance / danger?
Hold on, back the truck up. Are you saying that if I put the fuses
under the panel where they aren't accessible then my airplane will still
meet 14 CFR 91.205 (c) and that I won't need to carry spares?
I would read "that are accessible to the pilot in flight" to mean that
the fuse panel is accessible to the pilot, not the fusees since who
cares if you can get to the fuses if you can't get to the panel.
schu
Message 11
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| Subject: | Re: Questions about circuit protection. |
Robert L. Nuckolls, III wrote:
>
> Since you have subscribed to the ill-conceived notion
> of an 'avionics bus' then the simple solution is
> to COMBINED the functionality of the A-bus
> with the E-Bus and add the switch in series with
> the normal feedpath diode. You don't need to add
> a special bus to coddle radios that don't need
> coddling.
>
Thanks for taking the time to write all this out, I see where you are
coming from now.
schu
Message 12
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| Subject: | Re: Adding an antenna to improve on the ground reception? |
Message 13
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| Subject: | Simplicity and circuit protection |
The FAA has just released SAIB CE-10-11 "Electrical: Fire Hazard in
Resetting Circuit Breakers" for operators of TC aircraft and transports, but
the implications of it gives Bob's advice that much more teeth, IMHO. To
summarize, the Feds are recommending that circuit breakers NOT be reset once
they trip except under specific circumstances. The complete SAIB can be
found here:
https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf
So, if you shouldn't reset them, what good are they?
Rick Girard
Message 14
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| Subject: | Questions about circuit protection. |
Hi Bob;
I think some of us may be dealing with conflicting information from two
respected sources, yourself and in some cases the manufacturers. Garmin and
Grand Rapids for example specify their equipment to be off during starter
engagement, the Grand Rapids units do not have an on/off switch and as we
have recently learned the GTX 327 may not really be off just because you
selected off, and the use of a "A" bus is mentioned in the install manual.
So in Matt's defense it may not be his following an "ill conceived notion"
as you mentioned, but a desire to serve two masters.
Tim Andres
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Saturday, January 02, 2010 10:09 AM
Subject: Re: AeroElectric-List: Questions about circuit protection.
<nuckolls.bob@aeroelectric.com>
> >
> > Why not simply add a switch in series with your
> > e-bus normal feed path diode and label it
> > "Avionics Master". Then ditch the avionics bus
> > and run your avionics of concern along with
> > endurance necessities from the e-bus.
>
>It is my understanding that the purpose of the e-bus is to be able to
>open the battery contactor and instantly have the system load drop to
>whatever is on the e-bus making it easier and quicker for the pilot to
>shed unneeded load in the event of an alternator failure.
No. The E-bus is where you power things that are
part of your Plan-B for sustained flight battery
only. YOU decide what the E-hours are. If you plan
to maintain the battery such that E-power-hours
is equal to or less than battery capacity, great.
If some smaller performance value meets your design
goals, great. But DECIDE what those design goals
are and craft the system to match.
>To that end I put only required avionics on the e-bus and avionics that
>I don't absolutely need to have on an avionics bus thinking that this
>was in line with the design goals of using an e-bus.
Since you have subscribed to the ill-conceived notion
of an 'avionics bus' then the simple solution is
to COMBINED the functionality of the A-bus
with the E-Bus and add the switch in series with
the normal feedpath diode. You don't need to add
a special bus to coddle radios that don't need
coddling.
>So my question is this: Given that simple is always
>cheaper/lighter/more reliable, is it worth the weight/cost/complexity to
>add a bus and a switch so that I can keep my avionics off during start,
>and be able to instantly shed all non-critical loads? I thought it was,
>but it seems like you disagree.
As described above, the only increase in complexity
to meet your design goals for an A-bus is make the
E-bus double up in that capacity. Alternatively,
you can abandon the legacy prophylactic for an
A-bus and associated master switch. See:
>Also, what are others doing here? Are they simply using the built in
>power switch to turn stuff off at start (if the component has a built in
>switch.)
The avionics master switch was never really necessary
for the reasons imagined at the time it was created.
I remember. I was working as a tech writer at Cessna
when the AV master was conceived. I wrote sections
of maintenance manuals that spoke to the perceived hoards
of hazard lurked upon the bus waiting to pounce on
fragile radios.
See:
http://www.aeroelectric.com/articles/avmaster.pdf
http://www.aeroelectric.com/articles/spike.pdf
http://www.aeroelectric.com/articles/Philosophy/Whats_all_this_DO160_Stuff_A
nyhow.pdf
Today, we know better. There's no value to be added
by dedicating a specially protected bus to power
radios.
>I know that fuses/breakers/fuselinks protect the wiring, what I was
>missing was the part about problems with one component spreading to
>others instead of being isolated. I think I will just get fuse blocks
>per your recommendation for the reasons you mention, but also because
>problems with a fuse can be remedied in the air quickly and easily.
As Bob suggested in his earlier post, you might
like to review the philosophy of breakers vs.
fuses and the value of crafting a system where
there are no designed in nuisance trips of
fuses and no single accessory is "critical"
. . . i.e. a failure tolerant system
Fuse blocks can be tucked away out of sight,
out of reach and out of mind. You need only
ONE breaker and that only if you're using
crowbar ov protection. Otherwise, it can ALL
be out of reach fuses.
Bob . . .
Message 15
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| Subject: | Simplicity and circuit protection |
"What good are they?"
Easily reset (when back on the ground), easily pulled to disconnect during
maintenance, or certain in-flight conditions. No fuses to buy and carry.
Bevan
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Richard
Girard
Sent: Saturday, January 02, 2010 12:42 PM
Subject: AeroElectric-List: Simplicity and circuit protection
The FAA has just released SAIB CE-10-11 "Electrical: Fire Hazard in
Resetting Circuit Breakers" for operators of TC aircraft and transports, but
the implications of it gives Bob's advice that much more teeth, IMHO. To
summarize, the Feds are recommending that circuit breakers NOT be reset once
they trip except under specific circumstances. The complete SAIB can be
found here:
<https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf>
https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf
So, if you shouldn't reset them, what good are they?
Rick Girard
Message 16
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| Subject: | Re: Simplicity and circuit protection |
Just my opinion but you can buy an awful lot of fuses for the price of a
single C/B. As to being easily reset on the ground, that was exactly the
condition that led to the crash that prompted the SAIB.
Rick Girard
On Sat, Jan 2, 2010 at 3:11 PM, B Tomm <fvalarm@rapidnet.net> wrote:
> "What good are they?"
>
> Easily reset (when back on the ground), easily pulled to disconnect during
> maintenance, or certain in-flight conditions. No fuses to buy and carry.
>
> Bevan
>
> ------------------------------
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Richard
> Girard
> *Sent:* Saturday, January 02, 2010 12:42 PM
> *To:* aeroelectric-list@matronics.com
> *Subject:* AeroElectric-List: Simplicity and circuit protection
>
> The FAA has just released SAIB CE-10-11 "Electrical: Fire Hazard in
> Resetting Circuit Breakers" for operators of TC aircraft and transports,
> but the implications of it gives Bob's advice that much more teeth, IMHO. To
> summarize, the Feds are recommending that circuit breakers NOT be reset once
> they trip except under specific circumstances. The complete SAIB can be
> found here:
>
> https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf
>
> So, if you shouldn't reset them, what good are they?
>
> Rick Girard
>
> *
>
> href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c*
>
> *
>
> *
>
>
Message 17
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| Subject: | Re: Simplicity and circuit protection |
I've always agreed that breakers can be useful, but not because they can be reset
after they automatically trip.
On both the military aircraft and passenger jets I've flown, the most useful thing
about circuit breakers was always:
1) the ability to manually trip them when smoke starts pouring out of a system
which is still powered (happened once to a colleague of mine).
2) the ability to pull then reset non-tripped breakers, usually under engineering
guidance, to get a glitchy system to restart itself.
For 25 years in my experience, resetting an already tripped breaker was discouraged
or prohibited by SOPs in most circumstances, ground or flight, until maintenance
action was carried out. I'm not sure why this concept should be a surprise
to anyone.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279823#279823
Message 18
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| Subject: | Z-14 Switch Combos |
I'm getting a handle on Z-14 from an operational perspective and have a
couple of questions about the switch combinations that could create
issues.
Obviously with the added complexity of managing two batteries, two
alternators, and a cross feed can create some interesting combinations.
Are there any combo's that we should be aware of that would create over
voltage or any other scenarios of concern?
In the event of a failure (for example Alt 2 failure), is there a
specific order for shutting off the bad alt and then enabling the cross
feed?
Thanks,
Phil
Message 19
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| Subject: | Simplicity and circuit protection |
>From my recollection of the account I read somewhere on-line, that circuit
breaker was reset (on the ground) without any troubleshooting to determine
why it tripped and what, if any, damage has been caused. If this person
reset it in the air, there would be no difference in this case, other than
the fire would have started sooner. The point I did not make clear is that
to "reset when on the ground", to me means to troubleshoot that circuit, not
just to push it back in and see if a fire starts. Breakers and fuses do not
trip for no reason other than an over current event. The questions are,
what caused the over current event, did this event cause any damage, and
depending on those answers, is it likely to trip again if nothing else is
done but to reset it?
Bevan
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Richard
Girard
Sent: Saturday, January 02, 2010 2:13 PM
Subject: Re: AeroElectric-List: Simplicity and circuit protection
Just my opinion but you can buy an awful lot of fuses for the price of a
single C/B. As to being easily reset on the ground, that was exactly the
condition that led to the crash that prompted the SAIB.
Rick Girard
On Sat, Jan 2, 2010 at 3:11 PM, B Tomm <fvalarm@rapidnet.net> wrote:
"What good are they?"
Easily reset (when back on the ground), easily pulled to disconnect during
maintenance, or certain in-flight conditions. No fuses to buy and carry.
Bevan
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Richard
Girard
Sent: Saturday, January 02, 2010 12:42 PM
Subject: AeroElectric-List: Simplicity and circuit protection
The FAA has just released SAIB CE-10-11 "Electrical: Fire Hazard in
Resetting Circuit Breakers" for operators of TC aircraft and transports, but
the implications of it gives Bob's advice that much more teeth, IMHO. To
summarize, the Feds are recommending that circuit breakers NOT be reset once
they trip except under specific circumstances. The complete SAIB can be
found here:
<https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf>
https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf
So, if you shouldn't reset them, what good are they?
Rick Girard
href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matro
nics.com/Navigator?AeroElectric-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
Message 20
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| Subject: | Re: Simplicity and circuit protection |
For some things that move control surfaces, I'd actually *insist* on
pullable breakers....like electric trim, electric flaps, the
Autopilot, and even electronic ignition. Those are things that
some day you may want to find a way to pull power on...and would
likely not even think about resetting them in most circumstances.
Tim Olson - RV-10 N104CD
do not archive
mmayfield wrote:
> <mmayfield@ozemail.com.au>
>
> I've always agreed that breakers can be useful, but not because they
> can be reset after they automatically trip.
>
> On both the military aircraft and passenger jets I've flown, the most
> useful thing about circuit breakers was always:
>
> 1) the ability to manually trip them when smoke starts pouring out of
> a system which is still powered (happened once to a colleague of
> mine). 2) the ability to pull then reset non-tripped breakers,
> usually under engineering guidance, to get a glitchy system to
> restart itself.
>
> For 25 years in my experience, resetting an already tripped breaker
> was discouraged or prohibited by SOPs in most circumstances, ground
> or flight, until maintenance action was carried out. I'm not sure why
> this concept should be a surprise to anyone.
>
> Mike
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=279823#279823
>
>
Message 21
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| Subject: | Re: Questions about circuit protection |
>
>
>Hold on, back the truck up. Are you saying that if I put the fuses
>under the panel where they aren't accessible then my airplane will still
>meet 14 CFR 91.205 (c) and that I won't need to carry spares?
>
>I would read "that are accessible to the pilot in flight" to mean that
>the fuse panel is accessible to the pilot, not the fusees since who
>cares if you can get to the fuses if you can't get to the panel.
First, 14 CFR 91.205 doesn't apply to an amateur built
airplane. That's not to imply that the FARS don't have
some things to be considered . . . but you have no
obligation to consult these documents that apply to
type certificated aircraft only. Further, 91.205 isn't
the ONLY milestone at which your project is essentially
"un-certifiable".
But assume you adopt failure tolerance as a
design goal. For every piece of equipment
"critical" for the manner in which you plan to use
the airplane, then that piece of equipment needs to
be backed up with a plan-B. There are 100 times
more failures in a piece of electronics that DOES
NOT blow a fuse than there are failures that DO
blow a fuse. If that piece of equipment is deemed
critical, then having spare fuses for the circuit
that supports that system is whistling in the dark.
So assuming you have a back up for every POTENTIALLY
critical system, then if follows that there are NO
critical systems. Hence, whether or not you can reach
breakers or fuses for any system is immaterial.
Bob . . .
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