Matronics Email Lists Forum Index Matronics Email Lists
BBS Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Should a tripped circuit breaker be reset in flight?

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
user9253



Joined: 28 Mar 2008
Posts: 1311
Location: Riley TWP Michigan

PostPosted: Thu Oct 09, 2014 7:07 am    Post subject: Should a tripped circuit breaker be reset in flight? Reply with quote

There is an article in the October 2014 issue of Sport Aviation on page 92 titled, "I'll Never Do That Again". The author experienced an avionics failure while in IFR conditions. Other pilots in similar emergency situations have crashed. This pilot was very experienced. After briefly losing control, he was able to use backup instruments and land. While safely on the ground, he noticed a popped circuit breaker and reset it. It immediately tripped again, accompanied by an unusual smell. The pilot wrote, "I will never reset a breaker in the air. I did not have a fire, but I clearly was cooking something while I was on the ramp. Flames on the ground are a problem. Flames in the air are deadly."
Take away the resettable feature of circuit breakers and they have no advantage (in most cases) over fuses, other than the cool factor of the appearance of a neat row of breakers. Fuses cost less, weigh less, and never fail to open when overloaded.
Joe


- 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

_________________
Joe Gores
Back to top
View user's profile Send private message
rv8builder



Joined: 02 Jan 2009
Posts: 56

PostPosted: Thu Oct 09, 2014 9:35 am    Post subject: Re: Should a tripped circuit breaker be reset in flight? Reply with quote

In my former life as an airline pilot, the policy on reseting CB's in flight was "If it is absolutely needed for flight (gear, etc), one reset was allowed. If it was not needed for flight (galley, cabin lights, cabin entertainment, etc) no reset in flight was allowed.

Dale


- 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

_________________
Dale
Back to top
View user's profile Send private message
stearman456



Joined: 14 Aug 2010
Posts: 49

PostPosted: Thu Oct 09, 2014 12:38 pm    Post subject: Re: Should a tripped circuit breaker be reset in flight? Reply with quote

rv8builder wrote:
In my former life as an airline pilot, the policy on reseting CB's in flight was "If it is absolutely needed for flight (gear, etc), one reset was allowed. If it was not needed for flight (galley, cabin lights, cabin entertainment, etc) no reset in flight was allowed.

Dale


That pretty much covers my current airline's philosophy: "At the discretion of the captain ONE (1) reset is allowed, except for anything involving fuel" (gauge, pump, etc). For a fuel related item there is no reset - it becomes a problem for the maintenance guys at the next landing. And if it's something not required for the safe completion of the current flight then we just live with it being u/s.

Dan


- 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
Back to top
View user's profile Send private message Send e-mail
mmayfield



Joined: 09 Oct 2009
Posts: 39
Location: NSW Central Coast, Australia

PostPosted: Tue Oct 14, 2014 1:04 pm    Post subject: Re: Should a tripped circuit breaker be reset in flight? Reply with quote

Same in our airline. There are good reasons for not resetting tripped breakers, eg., causing the production of smoke when before there was none. FWIW in the never-ending "fuses versus breakers" debate, my design goals were:

1. The circuit protection shall be checked during preflight (a principle beaten into me during both military flying and airline training), and so tripped circuit protection devices must be easy to distinguish on the ground, and must be investigated before getting airborne.

2. In the air, tripped circuit protection shall be easily identifiable but not be reset/replaced unless I have a damn good reason for it.

3. In the air, circuit protection shall be easily reachable by system, such that if things produce unauthorised smoke, corresponding circuit protection can be manually tripped (as a backup to actually switching the system off, or in the case of items not having their own power switch).

I achieved these goals, slightly more easily IMHO, by using CBs rather than fuses although with the advent of illuminated fuses there's probably no reason why they couldn't achieve them too.

I do actually know of a couple of instances when I was in the military where boxes produced smoke airborne and CBs had to be pulled.


- 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

_________________
Mike
Back to top
View user's profile Send private message
jluckey(at)pacbell.net
Guest





PostPosted: Tue Oct 14, 2014 2:00 pm    Post subject: Should a tripped circuit breaker be reset in flight? Reply with quote

Mike,
All excellent points and it's good to hear from people who've had exposure to different organizations. I'm not an airline pilot & never served in the military.
I would like to clarify one point. In this and other posts, people have referred to fuse panels which have "fuse blown" indicators in the form of red LEDs mounted next to the fuse. I think these are really neat!
But, keep in mind that the LED is only lit when the fuse is blown AND the device on the other end is turned-on or at least capable of conducting a few milli-amps to ground. This means that if the circuit w/ the blown fuse is turned-off, the LED will not light and the blown fuse may go unnoticed.

An example will help illustrate. Let's say that while taxing back to your hangar one night, the landing light fuse blows. No big deal - you're on the ground & home - you'll fix it next weekend. Then, next weekend you get out to the plane and you forget about the inop landing light. The "fuse blown" LED will not light up when you power-up the buss because there is no path to ground for the LED.
This is really not a big deal, however, if that had been a breaker instead of a fuse, the breaker would still be 'popped' and sticking up when you got back to the plane. The point being that a popped circuit breaker can be a conspicuous reminder of a problem.
The argument could be made that a popped breaker is easier to detect than a blown fuse as Mike points out.

-Jeff



On Tuesday, October 14, 2014 2:17 PM, mmayfield <mmayfield(at)ozemail.com.au> wrote:



--> AeroElectric-List message posted by: "mmayfield" <mmayfield(at)ozemail.com.au (mmayfield(at)ozemail.com.au)>

Same in our airline. There are good reasons for not resetting tripped breakers, eg., causing the production of smoke when before there was none. FWIW in the never-ending "fuses versus breakers" debate, my design goals were:

1. The circuit protection shall be checked during preflight (a principle beaten into me during both military flying and airline training), and so tripped circuit protection devices must be easy to distinguish on the ground, and must be investigated before getting airborne.

2. In the air, tripped circuit protection shall be easily identifiable but not be reset/replaced unless I have a damn good reason for it.

3. In the air, circuit protection shall be easily reachable by system, such that if things produce unauthorised smoke , corresponding circuit protection can be manually tripped (as a backup to actually switching the system off).

I achieved these goals, slightly more easily IMHO, by using CBs rather than fuses although with the advent of illuminated fuses there's probably no reason why they couldn't achieve them too.

I do actually



[quote][b]


- 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
Back to top
stuart(at)stuarthutchison
Guest





PostPosted: Mon Oct 20, 2014 4:54 am    Post subject: Should a tripped circuit breaker be reset in flight? Reply with quote

G’day Mike,

There might be a few chuckles over your remark … not even Bob has a patent on good ideas, but mortals are on a hiding to nothing arguing electrical architectures with him Smile I have a long P3 Orion background where CBs are used (and sometimes abused) by the hundreds too, but it never ceases to amaze me how much common sense and experience Bob has in his head and how well he can describe it !

We’re in your debt … onya Bob.

Cheers, Stu
On 20 Oct 2014, at 9:39 pm, mmayfield <mmayfield(at)ozemail.com.au> wrote:

Quote:


Well Bob, you need to write to Boeing about addressing those issues and their system design or poorly conceived procedures because they are direct from the Boeing FCOM. Best of luck with that!

The "tea and biscuits" metaphor was just that. Yes he was called to explain what happened but in this particular case I don't believe it was actually an inquisitorial meeting (notwithstanding that it can be). However there was a reminder issued that checking the breaker panels is a preflight requirement and it was a big deal.

Even in my small plane, the breakers are there. They should all be in for engine start. Just like every other switch position I check before engine start in a standard panel scan, the breakers are part of that scan.

As an interesting aside, the Airbus A330 has all its physical breakers down in the electronics compartment. Technically it's accessible, but not within arms reach. However Airbus needed a way of allowing pilots to pull and reset power to systems so they created an overhead panel with "breaker-like" switches - they do not function as circuit protection but look exactly like breakers, and physically pull and push in the same manner!

It is quite common on the Airbus to use these to reset a system, both on the ground and in the air.

--------
Mike




Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=432067#432067












- 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
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group