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FAA Policy on Circuit Breakers (corrected)

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nuckolls.bob(at)cox.net
Guest

Posted: Fri Sep 28, 2007 7:52 pm Post subject: FAA Policy on Circuit Breakers (corrected)

At 09:06 PM 9/28/2007 -0600, you wrote:




<nuckolls.bob(at)cox.net>



At 08:06 PM 9/28/2007 -0400, you wrote:






I must agree with Bob on his response to this but an even simpler analysis 

is that the writer missed half of the breaker definition and assumed design 

intent!



"AC 23-17B, System and Equipment Guide for Certification of Part 23

Airplanes, (Amendment 23-49 and Subsequent) For part 23 applications,

the definitions of a switch and a circuit breaker are as follows: 1) A

switch is a device for opening and closing or for changing the

connection of a circuit; 2) A circuit breaker is a device designed to

open and close a circuit by non-automatic means and to open the circuit

automatically at a predetermined overload of current, without injury to

itself when properly applied within its rating. Thus, circuit breakers

used for operational functions are not acceptable because they are not

performing their intended function, which is protection against

overloads. "



According to the above definition the functions of a breaker are *"open and 

close a circuit by non-automatic means" *and *"to open the circuit

automatically at a predetermined overload of current"*. To conclude using 

the breaker as a switch is not acceptable assumes that only the second part 

of the definition is intended. If the breaker is the pullable type then 

switching is an intended function. If the designers intent was to restrict 

the use of the breaker as a switch then a non-pullable breaker could be 

applied. I would assume that if the intent was to restrict the switching 

function of a pullable breaker then a caution should be applied near the 

breaker or at least in the operation instructions.



Just my two cents.



--

Ralph C. Hoover



    Interesting take. I missed that. I'm trying to put the

    gray-matter around:



    "Thus, circuit breakers used for operational functions are

    not acceptable because they are not performing their

    intended function, which is protection against overloads."



    Does this mean that IF you use a breaker for any purpose,

    it's first function is for protection and switching is

    secondary? Therefore, the antithesis would suggest that

    if one uses a breaker primarily for it's capabilities

    as a switch and NO intent for protection is claimed,

    then the designer is to be shot at dawn?



    Bob . . .

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BobsV35B(at)aol.com
Guest

Posted: Sat Sep 29, 2007 3:50 am Post subject: FAA Policy on Circuit Breakers (corrected)

Good Morning 'Lectric Bob,   

 I must admit to not having read this entire thread thoroughly, but my take  on the original reference is that, rather than discussing circuit breaker  details and design subtleties, the FAA was telling their Designated Pilot  Examiners to be careful how they disable any of the new fangled glass cockpit  devices.  

  

 If it has an honest to goodness switch, disabling it might be considered  fair game. 

  

 If an examiner disables something by operating a circuit breaker, it could  lead to all sorts of litigious matters in the event of an incident.  

  

 Back when I was serving as a DPE (gliders only, but I did attend the DPE  meetings and listen to all of the discussions and guidance) it was recommended,  even insisted by some FAA types, that we NEVER pull a circuit breaker to disable  anything.

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



  

 In a message dated 9/28/2007 10:54:18 P.M. Central Daylight Time,  nuckolls.bob(at)cox.net writes:

  	  Quote: 	
		  Does    this mean that IF you use a breaker for any purpose,

    it's    first function is for protection and switching is

    secondary?    Therefore, the antithesis would suggest that

    if one uses a    breaker primarily for it's capabilities

    as a switch and NO    intent for protection is claimed,

    then the designer is to be    shot at dawn?



    Bob . . . 

	


 





See what's new="_blank">Make AOL Your Homepage.

  [quote][b]

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