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Switch Failure

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bruceflys(at)comcast.net
Guest

Posted: Sat Feb 25, 2006 6:01 am Post subject: Switch Failure

FWIW, I found this message on the GlaStar e-mail group:



Just thought that I would pass this along for everyone's edification. I 

noticed that my strobes were not working the other day so I checked the 

fuses and sure enough, the strobe fuse was blown. I replaced the fuse and it 

popped as soon as I flipped the master switch on. I traced the wire from the 

fuse panel to the toggle switch and there was no chafing or problems 

visible. I disconnected the wire that goes to the strobe power supply from 

the strobe switch and tried it again, POP! Now I'm looking right at the 18" 

of wire that goes from the fuse panel to the strobe switch and it's 

undamaged. The wire that goes to the power supply is disconnected and the 

switch is in the OFF position yet there is a dead short! I removed the 

switch and checked the continuity between the terminals and the body of the 

switch and sure enough, the switch was shorted internally. I replaced the 

switch with one of my spares and all was back to normal. I took the switch 

apart and found that the moving contact rocker inside the switch was 

touching the switch body. I'll include a photo of the switch guts for your 

amusement, you can see the arcing on the switch cover. The switch is from 

B&C and is a CARLING brand. I'll be sure that I carry a spare in my parts 

bag.

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rv8ch

Joined: 10 Jan 2006
Posts: 250
Location: Switzerland

Posted: Sat Feb 25, 2006 9:57 am Post subject: Switch Failure

 	  Quote: 	
		   touching the switch body. I'll include a photo of the switch guts for your 

 amusement, you can see the arcing on the switch cover. The switch is from 

 B&C and is a CARLING brand. I'll be sure that I carry a spare in my parts 

 bag. 


	


Can you put the photo on imageshack.us and send us a link?  First time

I've heard of someone with a failed switch.



Thanks,

Mickey

-- 

Mickey Coggins

http://www.rv8.ch/

#82007 finishing

do not archive

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_________________
Mickey Coggins
http://www.rv8.ch/

nuckollsr(at)cox.net
Guest

Posted: Sat Feb 25, 2006 1:16 pm Post subject: Switch Failure

At 08:54 AM 2/25/2006 -0500, you wrote:



 	  Quote: 	
		  

<bruceflys(at)comcast.net>



FWIW, I found this message on the GlaStar e-mail group:



Just thought that I would pass this along for everyone's edification. I

noticed that my strobes were not working the other day so I checked the

fuses and sure enough, the strobe fuse was blown. I replaced the fuse and it

popped as soon as I flipped the master switch on. I traced the wire from the

fuse panel to the toggle switch and there was no chafing or problems

visible. I disconnected the wire that goes to the strobe power supply from

the strobe switch and tried it again, POP! Now I'm looking right at the 18"

of wire that goes from the fuse panel to the strobe switch and it's

undamaged. The wire that goes to the power supply is disconnected and the

switch is in the OFF position yet there is a dead short! I removed the

switch and checked the continuity between the terminals and the body of the

switch and sure enough, the switch was shorted internally. I replaced the

switch with one of my spares and all was back to normal. I took the switch

apart and found that the moving contact rocker inside the switch was

touching the switch body. I'll include a photo of the switch guts for your

amusement, you can see the arcing on the switch cover. The switch is from

B&C and is a CARLING brand. I'll be sure that I carry a spare in my parts

bag.


	


    Please if you can. Send me the switch, removed with care to avoid

    disturbing it's condition. I'll reimburse you for any expense.

    It's VERY seldom we get to do an autopsy on field failures. So

    much of what's seen by technicians in the trenches is simply viewed

    as a maintenance issue with no interest in root causes. This makes

    our jobs as systems designers exceedingly more difficult. We cannot

    avoid or fix a condition for which we have no knowledge.



    Your cooperation in an effort to understand would be appreciated more

    than you know.



    Bob . . .

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sportav8r(at)aol.com
Guest

Posted: Sat Feb 25, 2006 5:14 pm Post subject: Switch Failure

An argument for switching the ground lead, vs the hot side, unless a stuck-on condition is dangerous?  Just a thought...

 

-Bill B 

 

--

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nuckollsr(at)cox.net
Guest

Posted: Sat Feb 25, 2006 6:48 pm Post subject: Switch Failure

At 08:13 PM 2/25/2006 -0500, you wrote:



 	  Quote: 	
		  



An argument for switching the ground lead, vs the hot side, unless a 

stuck-on condition is dangerous?  Just a thought...



-Bill B




	


   How would this be better? The same failure might then leave you with

   some accessory running where you couldn't turn it off. Of course, this

   gives rise to the secondary argument about having pullable breakers

   accessible to pilots, etc.



   I think I'd rather have it function exactly as described and get

   OFF line and out of consideration.  A second order consideration

   in the failure tolerance equation is not to increase workload. The

   switch died (albeit in what must be a really bizarre fashion) and

   the fuse did its job. All done.



   Bob . . .

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