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Magneto failure in general, Was: Re: P Mags

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BobsV35B(at)aol.com
Guest

Posted: Thu Feb 22, 2007 9:04 am Post subject: Magneto failure in general, Was: Re: P Mags

Good Morning Mike   

 My following comments do NOT mean I dislike magnetos, but if you have an  impulse magneto and the spring on the impulse fails, the same problem can occur.  

  

 That is one of the reasons that most good instructors teach that each  magneto should be shut down independently any time an engine gets rough. There  are other internal failure modes that will do the same thing.

  

 I have had the plastic gear strip and have had springs break. 

  

 Switching the bad magneto off put the engine back to running  normally.

  

 In some ways the very reliability of modern ignition systems has set us  up to not recognize failures when they occur. Sixty years ago, magneto  failures of that sort were common.

  

 One more good idea is to make a magneto check just before landing. That  check will be more meaningful if it is done at a fairly high cruise power  setting. Such a check is much more likely to catch a magneto, spark plug, or a  harness, that is getting marginal than is the low power check we do just before  takeoff.

  

 I would certainly not consider the failure mode of the E-Mag to be any  worse than failure modes that are common with any magneto.

  

 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 2/22/2007 9:50:39 A.M. Central Standard Time,  mlas(at)cox.net writes:

  	  Quote: 	
		  Frank is    right again!  The point he makes is as a very important.  What

is    the effect of an ignition system going off time?  In this case and

the    one I was involved with the P-mag appeared to go more    advanced.

Pre-ignition in an aircraft engine is a very bad thing!  So    it seems

that the change in potential timing advance could be a bigger    problem

then a strait forward failure.  Going back to Kelly's position    about

mags vs. CDI and the like, I believe this would be one for the mag    pro

side of the page.  Mind you, I run dual LSE Plasma III on one of    my

airplanes and love it.



Mike Larkin

	


 





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khorton01(at)rogers.com
Guest

Posted: Thu Feb 22, 2007 10:03 am Post subject: Magneto failure in general, Was: Re: P Mags

On 22 Feb 2007, at 12:01, BobsV35B(at)aol.com (BobsV35B(at)aol.com) wrote:

 	  Quote: 	
		      I would certainly not consider the failure mode of the E-Mag to be any worse than failure modes that are common with any magneto.

  

 

	




The failure mode that is described in the E-Mag service bulletin could affect both ignitions at once, if one had two E-Mag ignition systems installed.  The failure mode occurs when the system incorrectly uses negative MP pulses to trigger the timing Quick-Set mode.  The system is supposed to only sense positive pressure MP pulses, but due to a software problem, it will also sense negative pressure MP pulses.  Both ignition systems likely see the same MP pulses, so both ignitions could have their timing changed.  There are other protections that were intended to ensure that the Quick-Set mode could not be triggered in flight, but there are things the pilot may do in normal operation that could invalidate those protections.



http://emagair.com/E-MAG%20Service%20Bulletin1.pdf



I'm not aware of any magneto failure modes where one event could trigger both mags to fail at the same time.



 Kevin Horton

RV-8 (Finishing Kit)

Ottawa, Canada

http://www.kilohotel.com/rv8



 



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mprather(at)spro.net
Guest

Posted: Thu Feb 22, 2007 10:13 am Post subject: Magneto failure in general, Was: Re: P Mags

Hello Bob,



I have read/been-told that cycling the mag switch while at high power

settings might cause the engine to backfire if one mag is dead and the

other is turned back on, and that such a backfire might damage components

of the intake and exhaust systems..  What do you think about this?

Matt-



 	  Quote: 	
		  



 Good Morning Mike



 My following comments do NOT mean I dislike magnetos, but if you have an

 impulse magneto and the spring on the impulse fails, the same problem can

 occur.



 That is one of the reasons that most good instructors teach that each

 magneto should be shut down independently any time an engine gets rough.

 There  are

 other internal failure modes that will do the same thing.



 I have had the plastic gear strip and have had springs break.



 Switching the bad magneto off put the engine back to running  normally.



 In some ways the very reliability of modern ignition systems has set us

 up

 to not recognize failures when they occur. Sixty years ago, magneto

 failures

 of that sort were common.



 One more good idea is to make a magneto check just before landing. That

 check will be more meaningful if it is done at a fairly high cruise power

 setting. Such a check is much more likely to catch a magneto, spark plug,

 or a

 harness, that is getting marginal than is the low power check we do just

 before

 takeoff.



 I would certainly not consider the failure mode of the E-Mag to be any

 worse

 than failure modes that are common with any magneto.



 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 2/22/2007 9:50:39 A.M. Central Standard Time,

 mlas(at)cox.net writes:



 Frank is  right again!  The point he makes is as a very important.  What

 is  the effect of an ignition system going off time?  In this case and

 the  one I was involved with the P-mag appeared to go more  advanced.

 Pre-ignition in an aircraft engine is a very bad thing!  So  it seems

 that the change in potential timing advance could be a bigger  problem

 then a strait forward failure.  Going back to Kelly's position  about

 mags vs. CDI and the like, I believe this would be one for the mag  pro

 side of the page.  Mind you, I run dual LSE Plasma III on one of  my

 airplanes and love it.



 Mike Larkin





 <BR><BR><BR>**************************************<BR> AOL now offers free

 email to everyone.  Find out more about what's free from AOL at

 http://www.aol.com.

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BobsV35B(at)aol.com
Guest

Posted: Thu Feb 22, 2007 10:54 am Post subject: Magneto failure in general, Was: Re: P Mags

Good Afternoon Matt,   

 The procedure, as taught, is to be very sure you DO NOT turn on the  remaining good magneto if the engine does quit. The drill then is to put the  mixture in full lean, count to ten, turn on the magneto and slowly richen the  mixture until the engine starts.

  

 I have never had it happen that way and I am sure it will take a lot of  discipline to wait those few seconds for the engine to clear itself before the  magneto is placed back in service!

  

 It does help if the operator has experience deliberately running fuel tanks  dry. 

  

 That procedure is another one that is rarely taught these days, but having  run a tank dry often does instill confidence in the restart procedure.

  

 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 2/22/2007 12:16:43 P.M. Central Standard Time,  mprather(at)spro.net writes:

  	  Quote: 	
		  I have    read/been-told that cycling the mag switch while at high power

settings    might cause the engine to backfire if one mag is dead and the

other is    turned back on, and that such a backfire might damage components

of the    intake and exhaust systems..  What do you think about    this?

Matt-

	


 





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BobsV35B(at)aol.com
Guest

Posted: Thu Feb 22, 2007 11:01 am Post subject: Magneto failure in general, Was: Re: P Mags

Good Afternoon Ken,   

 Well, as long as we are discussing potential multiple failures or single  point failures, what happens when the drive gear on a dual magneto fails?

  

 In any case, I meant to be responding to the potential of getting a magneto  out of time as happened on the flight being discussed. 

  

 The Service Bulletin was not what I had in mind, but anything made by man  is subject to some sort of failure mode.

  

 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 2/22/2007 12:05:56 P.M. Central Standard Time,  khorton01(at)rogers.com writes:

  	  Quote: 	
		        On 22 Feb 2007, at 12:01, BobsV35B(at)aol.com (BobsV35B(at)aol.com) wrote:

    	  Quote: 	
		                      I would certainly not consider the failure mode of the E-Mag to be any      worse than failure modes that are common with any magneto.

      



	




   The failure mode that is described in the E-Mag service bulletin could    affect both ignitions at once, if one had two E-Mag ignition systems    installed.  The failure mode occurs when the system incorrectly uses    negative MP pulses to trigger the timing Quick-Set mode.  The system is    supposed to only sense positive pressure MP pulses, but due to a software    problem, it will also sense negative pressure MP pulses.  Both ignition    systems likely see the same MP pulses, so both ignitions could have their    timing changed.  There are other protections that were intended to ensure    that the Quick-Set mode could not be triggered in flight, but there are things    the pilot may do in normal operation that could invalidate those    protections.

   

   http://emagair.com/E-MAG%20Service%20Bulletin1.pdf



   I'm not aware of any magneto failure modes where one event could trigger    both mags to fail at the same time.



      Kevin Horton

   RV-8 (Finishing Kit)

   Ottawa, Canada

   http://www.kilohotel.com/rv8



	


 





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BobsV35B(at)aol.com
Guest

Posted: Thu Feb 22, 2007 11:12 am Post subject: Magneto failure in general, Was: Re: P Mags

In a message dated 2/22/2007 1:05:51 P.M. Central Standard Time,  BobsV35B(at)aol.com writes:

  	  Quote: 	
		  Good    Afternoon Ken, 	


 

OOOPs!! should have been:

  

 Good Afternoon Kevin,

  

 Sorry about that.

  

 Do Not Archive

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



AOL now offers free email to everyone.  Find out more about what's free from AOL 326657x4311227241x4298082137/aol?redir=http%3A%2F%2Fwww%2Eaol%2Ecom" target="_blank">AOL.com.  [quote][b]

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mprather(at)spro.net
Guest

Posted: Thu Feb 22, 2007 12:05 pm Post subject: Magneto failure in general, Was: Re: P Mags

Aha...  That clears it up for me.  Thanks for the description of the

correct procedure.  And, yes it would take some discipline to keep from

just turning the mag back on...

Regards,



Matt-



 	  Quote: 	
		  



 Good Afternoon Matt,



 The procedure, as taught, is to be very sure you DO NOT turn on the

 remaining good magneto if the engine does quit. The drill then is to put

 the  mixture

 in full lean, count to ten, turn on the magneto and slowly richen the

 mixture

 until the engine starts.



 I have never had it happen that way and I am sure it will take a lot of

 discipline to wait those few seconds for the engine to clear itself before

 the

 magneto is placed back in service!



 It does help if the operator has experience deliberately running fuel

 tanks

 dry.



 That procedure is another one that is rarely taught these days, but having

 run a tank dry often does instill confidence in the restart procedure.



 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 2/22/2007 12:16:43 P.M. Central Standard Time,

 mprather(at)spro.net writes:



 I have  read/been-told that cycling the mag switch while at high power

 settings  might cause the engine to backfire if one mag is dead and the

 other is  turned back on, and that such a backfire might damage components

 of the  intake and exhaust systems..  What do you think about  this?

 Matt-





 <BR><BR><BR>**************************************<BR> AOL now offers free

 email to everyone.  Find out more about what's free from AOL at

 http://www.aol.com.

- 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:

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khorton01(at)rogers.com
Guest

Posted: Thu Feb 22, 2007 12:39 pm Post subject: Magneto failure in general, Was: Re: P Mags

Bob,

I share your concern with dual drive magnetos, and would not want to own an engine with such a beast.

Kevin Horton



On 22 Feb 2007, at 13:58, BobsV35B(at)aol.com (BobsV35B(at)aol.com) wrote:

 	  Quote: 	
		      Good Afternoon Ken,  

 Well, as long as we are discussing potential multiple failures or single point failures, what happens when the drive gear on a dual magneto fails?

  

 In any case, I meant to be responding to the potential of getting a magneto out of time as happened on the flight being discussed. 

  

 The Service Bulletin was not what I had in mind, but anything made by man is subject to some sort of failure mode.

  

 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 2/22/2007 12:05:56 P.M. Central Standard Time, khorton01(at)rogers.com (khorton01(at)rogers.com) writes:

  	  Quote: 	
		      On 22 Feb 2007, at 12:01, BobsV35B(at)aol.com (BobsV35B(at)aol.com) wrote:

   	  Quote: 	
		                  I would certainly not consider the failure mode of the E-Mag to be any     worse than failure modes that are common with any magneto.

     



	




  The failure mode that is described in the E-Mag service bulletin could   affect both ignitions at once, if one had two E-Mag ignition systems   installed.  The failure mode occurs when the system incorrectly uses   negative MP pulses to trigger the timing Quick-Set mode.  The system is   supposed to only sense positive pressure MP pulses, but due to a software   problem, it will also sense negative pressure MP pulses.  Both ignition   systems likely see the same MP pulses, so both ignitions could have their   timing changed.  There are other protections that were intended to ensure   that the Quick-Set mode could not be triggered in flight, but there are things   the pilot may do in normal operation that could invalidate those   protections.

  

  http://emagair.com/E-MAG%20Service%20Bulletin1.pdf



  I'm not aware of any magneto failure modes where one event could trigger   both mags to fail at the same time.



    Kevin Horton

  RV-8 (Finishing Kit)

  Ottawa, Canada

  http://www.kilohotel.com/rv8



	




	


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