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RE Contactor Failure

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emrath(at)comcast.net
Guest

Posted: Mon Nov 30, 2009 4:30 pm Post subject: RE Contactor Failure

I failed a battery contactor during my build up process about a year ago.

The plane had not flown and the starter never  used. I went to "light up the

panel" for about the 20th demo and it didn't pull in. B&C replaced the

contactor at no cost. I still have the contactor, intending to do an autopsy

sometime.

Marty in Brentwood TN



Time: 05:47:53 PM PST US

From: Speedy11(at)aol.com

Subject: Contactor Failure



Any folks had a contactor failure?

My understanding was that contactors are not failure prone.  I  understood 

that was the reasoning behind inserting one between the battery and  the 

starter solenoid.

I had one fail the other day (actually it stuck in the closed position)  

after 40 hours of use.  It was an intermittent duty contactor installed  

between the #4 welding cable from the positive battery post and the Skytec  

starter.

If my engine doesn't start on the third blade, I release the starter button 

 to check what I've missed and try it again.  When I released the starter  

button, the prop kept turning.  I quickly hit the starter button again  

thinking it might have stuck.  The blades kept turning.  I turned off  both 

batteries and all fuel source.  The blades had stopped by then (10  seconds)

but



the starter was still engaged.  Set the brake and ran to the  hangar for 

wrenches.  I had to disconnect the battery to stop the  starter.  There was

no



other way.

Did I design in a fault?  Aren't most custom-built airplanes built  with a 

contactor between the hot battery and the starter?  Should I have  some 

other type of disconnect between the battery and the contactor? Stan

Sutterfield RV-8A flying

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Nov 30, 2009 5:54 pm Post subject: RE Contactor Failure

At 06:27 PM 11/30/2009, you wrote:

 	  Quote: 	
		  



I failed a battery contactor during my build up process about a year ago.

The plane had not flown and the starter never  used. I went to "light up the

panel" for about the 20th demo and it didn't pull in. B&C replaced the

contactor at no cost. I still have the contactor, intending to do an autopsy

sometime.


	


  I'd be pleased to do that for you and report to the

  List . . . or in any event, please let us know what

  you discover.



  I was make privy to an interesting failure in a Type-70

  product some time back. See:



http://aeroelectric.com/Pictures/Failures/W-R_RBM_3-Terminal_2s.jpg



  . . . seems the solder terminal for the coil wire was

  mis-clocked 90 degrees and was arcing against the

  moving contact ring when the contactor was energized.



http://www.aeroelectric.com/Pictures/Contactors/S701-1a.jpg



http://www.aeroelectric.com/Pictures/Contactors/S701-1e.jpg



This contactor was a later manufacturing date and did

not use the same process for bringing coil current out.

The joint is shielded in later production.



http://www.aeroelectric.com/Pictures/Contactors/S701-1b.jpg



        Bob . . .



         ---------------------------------------

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