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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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 Posted: Sat Jan 02, 2010 12:44 pm Post subject: Simplicity and circuit protection |
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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
[quote][b]
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fvalarm(at)rapidnet.net
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| Posted: Sat Jan 02, 2010 1:13 pm Post subject: Simplicity and circuit protection |
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"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(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Richard Girard
Sent: Saturday, January 02, 2010 12:42 PM
To: aeroelectric-list(at)matronics.com
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
[quote]
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
[b]
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jindoguy(at)gmail.com
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| Posted: Sat Jan 02, 2010 2:14 pm Post subject: Simplicity and circuit protection |
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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(at)rapidnet.net (fvalarm(at)rapidnet.net)> wrote:
[quote] "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(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Richard Girard
Sent: Saturday, January 02, 2010 12:42 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
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
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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[b]
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mmayfield
Joined: 09 Oct 2009
Posts: 40
Location: NSW Central Coast, Australia
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| Posted: Sat Jan 02, 2010 5:16 pm Post subject: Re: Simplicity and circuit protection |
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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
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fvalarm(at)rapidnet.net
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| Posted: Sat Jan 02, 2010 7:43 pm Post subject: Simplicity and circuit protection |
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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(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Richard Girard
Sent: Saturday, January 02, 2010 2:13 PM
To: aeroelectric-list(at)matronics.com
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(at)rapidnet.net (fvalarm(at)rapidnet.net)> wrote:
[quote] "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(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Richard Girard
Sent: Saturday, January 02, 2010 12:42 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
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
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
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
[b]
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Tim Olson
Joined: 25 Jan 2007
Posts: 2879
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| Posted: Sat Jan 02, 2010 8:08 pm Post subject: Simplicity and circuit protection |
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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:
| Quote: |
<mmayfield(at)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 79823#279823
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MauleDriver(at)nc.rr.com
Guest
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| Posted: Sun Jan 03, 2010 6:52 am Post subject: Simplicity and circuit protection |
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I adopted that same thinking. The only pullable breakers I have are
flaps and AP. I have the Safety Trim system that is supposed to
limit/control runaway trim situations.
Bill Watson - still building
Tim Olson wrote:
| Quote: |
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(at)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 79823#279823
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Jan 04, 2010 12:02 pm Post subject: Simplicity and circuit protection |
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At 07:16 PM 1/2/2010, you wrote:
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).
Certainly possible but exceedingly low risk. It
also presumes the pilot can identify the specific
system.
2) the ability to pull then reset non-tripped breakers, usually under
engineering guidance, to get a glitchy system to restart itself.
Not unusual in a revenue generating environment
manned by professionals. But after a couple
of "glitches" in my OBAM aircraft electro-whizzy,
I think I'd be sending it back to the factory
for a fix or my money back.
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.
Just read the dark-n-stormy night stories offered
in the so-called aviation education journals. When
electrical systems issues are part of story, there's
plenty of breaker pulling, switch flipping and
real time mis-interpretation of symptoms that
drive the story-teller's probability of success
(both UP and DOWN) during his/her narrow escape.
As a professional, you had a different set of
teachers than did us lowly tin-can drivers. Unless
a pilot takes a special interest in understanding
things like failure mode effects analysis and
deducing actions that are useful or at least
don't make things worse, then the outcome
is problematic. To make matters worse, those
who publish such stories seem never offer a de-briefing
and lessons-learned study by teachers who DO
understand the system. (See chapter 17 of the
'Connection) The 'education' may be worse than
having not printing the story in the first place.
It is difficult to perform to standards any greater
than our level of education makes possible.
Bob . . .
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Mon Jan 04, 2010 12:15 pm Post subject: Simplicity and circuit protection |
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At 02:42 PM 1/2/2010, you wrote:
| Quote: | 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? |
Exactly what they were designed for . . . keep a single
system fault from propagating to other systems or more
serious symptoms. In hindsight, we would have been
better off since day-one had TC aircraft designers
had be chartered to design for failure tolerance (el-
cheeso parts not necessarily poor value) as
opposed to failure avoidance (gross reliability).
After all, the earliest electrical systems were
pure automotive bolt-on hardware. Not necessarily
evil but they could have evolved in more practical
directions if we had no placed them on pedestals
and started certifying their socks off.
If I were chartered to craft a system with breakers
I'm pretty certain I'd figure out a way to make
the breaker panel just as inaccessible as the fuse
blocks. This forces the design off in new and
more useful directions.
Bob . . .
[quote][b]
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