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EXP 2 Bus workaround
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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 9:30 am Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
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		   	  Quote: 	
		   	  Quote: 	
		  Can you spin your starter w/ the Master Switch off? 	
	
	


    Why would you want access to the

    starter with the master switch off?

    Under what conditions would you first

    have the switch off and then find that

    the engine has assumed a condition that

    needs encouragement to get running again?

    Assuming that the engine is at risk for

    doing such a thing, what prevents you

    from turning the master switch back on?



	




Bob...my imagination knows no limits...I'm thinkin the Master's off after detecting smoke and acrid smells coming from the panel...I'm wanting to avoid the risk of flippin the Master back on and exacerbating the situation which caused me to flip it off in the first place.

Fred

 [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 9:57 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		  Bob...my imagination knows no limits...I'm thinkin the Master's off 

after detecting smoke and acrid smells coming from the panel...I'm 

wanting to avoid the risk of flippin the Master back on and 

exacerbating the situation which caused me to flip it off in the first place.


	


   Okay, so that's a really big failure or a combination of

   more than one failure giving you both Smoke + engine quits.

   If you've suffered an event that stops the engine AND

   smells bad . . . well . . .



   The configuration on which we're sifting the sands

   will allow you to turn off every switch except Engine A

   without killing the engine electrically. Hmmm . . . perhaps

   Engine A needs to run from the battery, Engine B from the

   main bus. Now, the statement I made above is true.



   Even so, unless you've got a clutched PRSU then you're

   not going to need the starter anyhow. If the engine

   has lost power due to same event that's causing smoke

   . . . it's likely that mitigation of risk for

   that cause is far outside the manipulation of any switches.





   Bob . . .

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 10:22 am Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  Even so, unless you've got a clutched PRSU then you're

 not going to need the starter anyhow. If the engine

 has lost power due to same event that's causing smoke

 . . . it's likely that mitigation of risk for

 that cause is far outside the manipulation of any switches.

	




Bob...I wouldn't disagree with you.

The origin of this question arose when you noted that my Revision XX diagram showed the starter switch fed from the engine (sorry, MP) bus rather than the main bus...I still don't see the down side if I were to do this.

Fred



 [quote][b]

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sat Oct 26, 2013 10:37 am Post subject: EXP 2 Bus workaround

Fred;  

   

Not meaning to be critical or judgmental, but your “properly designed” and maintained electrical system has somehow found a way to generate “smoke in the cockpit” and you’ve turned off the master switch. So far so good.   

The electrical problem (or fire) has progressed to the point of stopping the engine and now you want to be further distracted by operating the starter to turn over the failed engine rather than to “FLY THE AIRCRAFT” to a controlled landing ????   

In order to stop, the engine must have been denied either fuel, spark or mechanical integrity, and for it to restart you must determine and restore whichever element is missing before the starter will be of any use. (and you’ve had to aerodynamically stall the airframe to stop the engine’s wind milling rotation) With all the redundancies and complexities you’re proposing you’re unlikely to troubleshoot and solve the problem in the air.   

It’s excellent to think up and have a solution for the various scenarios, but at some point you need to follow the KISS principle and not layer one “what if” on top of another. The likelihood of two or more failures on any one flight on a properly designed and maintained aircraft are exceeding unlikely.   

By all means design for any single “what if” or failure you can possibly conceive, but to layer one on top of another on top of another and try to have a work-around is just going to increase the likelihood of a problem not decrease it.  

   

Just my unsolicited two cents which you’re quite entitled to delete or ignore (or deposit in the bank if you so desire)  

   

Bob McC  

           

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Fred Klein

 Sent: Saturday, October 26, 2013 1:30 PM

 To: aeroelectric-list(at)matronics.com

 Subject: Re: AeroElectric-List: EXP 2 Bus workaround  

  

   

       

On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote:  

  



 

      	  Quote: 	
		     	  Quote: 	
		     	  Quote: 	
		    

Can you spin your starter w/ the Master Switch off?  	
  	
  	
  



     Why would you want access to the

     starter with the master switch off?

     Under what conditions would you first

     have the switch off and then find that

     the engine has assumed a condition that

     needs encouragement to get running again?

     Assuming that the engine is at risk for

     doing such a thing, what prevents you

     from turning the master switch back on?  

  

   

    

Bob...my imagination knows no limits...I'm thinkin the Master's off after detecting smoke and acrid smells coming from the panel...I'm wanting to avoid the risk of flippin the Master back on and exacerbating the situation which caused me to flip it off in the first place.  

    

   

    

Fred  

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_________________
Bob McC
Falco #908
(just starting)

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 11:26 am Post subject: EXP 2 Bus workaround

At 01:21 PM 10/26/2013, you wrote:



 	  Quote: 	
		  On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote:



>Even so, unless you've got a clutched PRSU then you're

>  not going to need the starter anyhow. If the engine

>  has lost power due to same event that's causing smoke

>  . . . it's likely that mitigation of risk for

>  that cause is far outside the manipulation of any switches.



Bob...I wouldn't disagree with you.



The origin of this question arose when you noted that my Revision XX 

diagram showed the starter switch fed from the engine (sorry, MP) 

bus rather than the main bus...I still don't see the down side if I 

were to do this.


	


    You're still wrapped around the axles of distraction.

    Let's get your list of loads spread out on the

    hypothetical architecture I published . . . and sift

    the FEMA/operational sands for that configuration.



    Then we can begin to study a means by which the EXP-Bus

    can morph into the same architecture. It may be that

    the starter switch gets powered from someplace different

    simply because you've run out of polyfuses on a particular

    bus. But downside or upside cannot be discussed until after

    roll-call.



    I have a finite amount of time to offer to this process . . .



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 11:38 am Post subject: EXP 2 Bus workaround

At 01:36 PM 10/26/2013, you wrote:

  	  Quote: 	
		   Fred;

  

 Not meaning to be critical or judgmental, but your “properly designed” and maintained electrical system has somehow found a way to generate “smoke in the cockpit” and you’ve turned off the master switch. So far so good. 

 The electrical problem (or fire) has progressed to the point of stopping the engine and now you want to be further distracted by operating the starter to turn over the failed engine rather than to “FLY THE AIRCRAFT” to a controlled landing ???? 	


   Gently my friend. Members here on the is are, for the most

   part, not aviation professionals. Fewer still have a grasp

   on the materials, processes and what-if analysis that goes

   into crafting the elegant solution.  There was a time when

   Z-19 was considered a 'solution' and to be sure, every feature

   on it operates in a predicable manner with no surprises.



   Fred's willingness to participate in this exercise has

   prompted a review of the ideas on which Z-19 stands along

   with brain-storming for simpler alternatives based on

   better ideas.



   Fred has mentioned that a friend of his opined that

   many band-aid-on-top-of-band-aid designs on airplanes

   to be products of ignorance and poor logic. Yup, those

   things happen.



   I've watched it my whole career in situations where I

   was one of many and with little influence. It doesn't even

   take a design by committed/regulation to produce an

   accident waiting to happen. Review the materials I posted

   on the N811HB accident.



   Many individuals who monitor the List have expressed

   a reluctance to post lest they become targets of

   words that fall outside the realm of entertaining

   and persuasive information.



   This is a classroom and it's my greatest wish that

   people carry knowledge out the door that adds value to

   their aviation experience.



 

 

   Bob . . .    [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sat Oct 26, 2013 11:51 am Post subject: Re: EXP 2 Bus workaround

I have learned a lot in your classroom.  Thanks Bob.

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 11:54 am Post subject: EXP 2 Bus workaround

At 02:51 PM 10/26/2013, you wrote:

 	  Quote: 	
		  



I have learned a lot in your classroom.  Thanks Bob.


	


   . . . and you've been an honorable participant for

   which I thank YOU.



   Bob . . .

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sat Oct 26, 2013 12:21 pm Post subject: EXP 2 Bus workaround

   

           

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III

 Sent: Saturday, October 26, 2013 3:38 PM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: AeroElectric-List: EXP 2 Bus workaround  

  

   

At 01:36 PM 10/26/2013, you wrote:

 

   

Fred;

  

 Not meaning to be critical or judgmental, but your properly designed and maintained electrical system has somehow found a way to generate smoke in the cockpit and youve turned off the master switch. So far so good. 

 The electrical problem (or fire) has progressed to the point of stopping the engine and now you want to be further distracted by operating the starter to turn over the failed engine rather than to FLY THE AIRCRAFT to a controlled landing ????  



   Gently my friend.   

Was trying to be. If it came across differently, that was not the intention. I apologize.  

   

Members here on the is are, for the most

   part, not aviation professionals. Fewer still have a grasp

   on the materials, processes and what-if analysis that goes

   into crafting the elegant solution.  There was a time when

   Z-19 was considered a 'solution' and to be sure, every feature

   on it operates in a predicable manner with no surprises.  

Agree  



   Fred's willingness to participate in this exercise has

   prompted a review of the ideas on which Z-19 stands along

   with brain-storming for simpler alternatives based on

   better ideas.  

And many of his (and others) scenarios point to the areas of potential improvement.

 

   Fred has mentioned that a friend of his opined that

   many band-aid-on-top-of-band-aid designs on airplanes

   to be products of ignorance and poor logic. Yup, those

   things happen.  

Part of the point of my original comment was intended to not lose sight of that philosophy.  



   I've watched it my whole career in situations where I

   was one of many and with little influence. It doesn't even

   take a design by committed/regulation to produce an

   accident waiting to happen. Review the materials I posted

   on the N811HB accident.  

Exactly.

 

   Many individuals who monitor the List have expressed

   a reluctance to post lest they become targets of

   words that fall outside the realm of entertaining

   and persuasive information.  

Myself included, but part of the issue is not that the thoughts are intended to be critical or demeaning in any way shape or form but that perhaps the command of English usage or even the degree of articulation is lacking so that comments are misinterpreted.

 

   This is a classroom and it's my greatest wish that

   people carry knowledge out the door that adds value to

   their aviation experience.  

Absolutely. I’ve learned immeasurably through lurking here many years, but as you’ve stated I’m often reluctant to share because of the fear of misstating my thoughts or verbalizing in a way that is open to misinterpretation. E-mails lack the intonations of a face to face conversation that sometimes conveys as much meaning as the actual words.  

  Bob . . .   

Once again, if my wording was inappropriate, I apologize. I’ll keep quiet now.  

Bob McC   	  Quote: 	
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_________________
Bob McC
Falco #908
(just starting)

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 12:56 pm Post subject: EXP 2 Bus workaround

 	  Quote: 	
		     Gently my friend. 

 Was trying to be. If it came across differently, that was not the intention. I apologize. 	


   Understand. Perhaps is was the bold, technicolor font that

   offered a poor first blush. That is a down-side for keyboard

   communications. We can be deprived of useful communications

   data when relying on the written word. 



   No value to be shared in 'being quiet' . . . the ideas you

   proffered were sound.



   I'm kind of 'stoked with this thread. There's not been

   a new z-figure in years. This is a good thing that

   these things get debated. Fred's worries about the

   smoke+silence failure prompted a thought on my part

   that perhaps Engine A switch ought to power from the

   battery with backup being Engine B from the main bus.



   This is backwards from how we've used the e-bus but it

   does suggest better human factors for powering down

   the electrics while leaving the engine up.



 



 

   Bob . . .    [quote][b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 1:10 pm Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 11:36 AM, Bob McCallum wrote:

 	  Quote: 	
		  Not meaning to be critical or judgmental, but your “properly designed” and maintained electrical system has somehow found a way to generate “smoke in the cockpit” and you’ve turned off the master switch. So far so good. 	




Thanks Bob M....I needed that...sometimes my imagination needs a comeuppance and a breath of fresh air...Fred 



 [quote][b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 1:16 pm Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 12:25 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  You're still wrapped around the axles of distraction.

  Let's get your list of loads spread out on the

  hypothetical architecture I published . . . and sift

  the FEMA/operational sands for that configuration.

	




I'm on it Bob...thanks, Fred



 [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sat Oct 26, 2013 1:19 pm Post subject: Re: EXP 2 Bus workaround

I have drawn a schematic (attached) for Fred using the EXP Bus.  It might not be as good as Bob's designs, but I think it is better than many TC aircraft electrical systems.  Fred definitely does not want to take a soldering iron to the circuit board.  So I could not make some changes that I would like to.  If Fred decides to use my schematic, the only changes that he will have to make will be pulling fast-on connectors off from switches and moving them around.  The main feature of this schematic is the addition of a master relay that is in parallel with the battery contactor.  Not to worry, this relay can not be energized while starting the engine.  The switch, that is normally the master switch, must be off in order to start the engine.  This also serves as a theft deterrent because a thief will turn on what he thinks is the master switch, but the engine will not start.  The former avionics master switch now controls the battery contactor.  Since the new master switch also turns on the alternator field, the former ALT switch can now be used for the second fuel pump.  I think that the EXP Bus has enough switches so that additional switches will not have to be added to the panel.

  Now that I am all done with the schematic and stand back and look at the big picture, I see that in case the EXP Bus smokes, shutting off the master switches will also kill the engine.  How to fix that?  How about an Engine bus fed by the master relay and also by a diode from the EXP Bus?

  Comments are welcome.  Just do not be too hard on me.  

Joe

PS Removed attachments.  Revised schematic is attached to my next post.

_________________
Joe Gores

Last edited by user9253 on Sun Oct 27, 2013 8:17 am; edited 2 times in total

uuccio(at)gmail.com
Guest

Posted: Sun Oct 27, 2013 6:39 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		   If you're willing to have an always hot feeder to a

 starter contactor . . .

	


That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage. 

 [quote][b]

jluckey(at)pacbell.net
Guest

Posted: Sun Oct 27, 2013 7:07 am Post subject: EXP 2 Bus workaround

From: Sacha <uuccio(at)gmail.com>

 To: "aeroelectric-list(at)matronics.com" <aeroelectric-list(at)matronics.com> 

 Sent: Sunday, October 27, 2013 6:24 AM

 Subject: Re: Re: EXP 2 Bus workaround

  	  Quote: 	
		   If you're willing to have an always hot feeder to a

 starter contactor . . .

That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage. 

That is not the case, with the master off you will not be able to crank as the coil circuit for starter contactor will not be powered.  See dwg.

-Jeff

http://www.matronics.com/Navigator?AeroElectric=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3DD=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D  [/b][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Oct 27, 2013 7:14 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		  That doesn't sound very safe when you're on he ground. Keys are out, 

master etc off, someone is by the prop and someone else accidentally 

actuates the starter by pushing the starter button or whatever. Even 

if the engine doesn't start you can still do some damage.


	


    There are TWO inputs to a starter contactor.

    FAT wire power to operate the motor and

    small wire power through the starter switch

    to energize the contactor coil. One COULD

    consider an always hot FAT wire that bypasses

    the battery contactor while shutting down

    the power source for the starter push-button.

    But this is contrary to legacy design goals

    for achieving max-dark on an electrical system

    when all switches are OFF.

   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Oct 27, 2013 7:58 am Post subject: Re: EXP 2 Bus workaround

I figured out the reason for D3 in the EXP2Bus (questioned in a previous 

post).  When the master switch is open, D3 prevents current from flowing in 

series through the master contactor coil and into the EXP2Bus.

  I drew a new schematic (pdf attached) using the EXP2Bus and also a 

separate Engine Bus.  I also have a dwg version if anyone is interested.

The Engine bus is fed from two paths so that any one failure will not cut 

power to the engine.  The EXP2Bus also has outputs that can supply engine loads.

  An endurance bus is not needed because the SkyView and GPS both have 

internal backup batteries.  The COM radio is powered by either the EXP2Bus 

or by the ENG bus through dual diodes inside of the EXP2Bus (CLRNC DEL input).

Comments and suggestions welcome.

Joe

EXP2 & ENG BUS.pdf

Description:

Download

Filename:

EXP2 & ENG BUS.pdf

Filesize:

505.28 KB

Downloaded:

289 Time(s)

_________________
Joe Gores

Last edited by user9253 on Sun Oct 27, 2013 8:58 am; edited 1 time in total

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Sun Oct 27, 2013 8:53 am Post subject: Re: EXP 2 Bus workaround

Bob,

What are your thoughts on having a separate switch for the alternator

 field versus using the second half of a double pole master switch?

  I know that your designs use a progressive transfer switch with the center 

position battery only with the alternator off.  But I am thinking about the 

EXP2Bus (or any electrical system) that does not have the progressive 

transfer switch, just a common DPDT switch.  Assuming the pilot has a plan B, 

for instance an E-Bus, she could shut off the one DPDT Master-Alt switch in 

the event of an alternator failure.  Most likely the pilot will want the master off 

anyway to conserve the battery.

  Or is it better to have a separate Alt switch?

Thanks, Joe

_________________
Joe Gores

uuccio(at)gmail.com
Guest

Posted: Sun Oct 27, 2013 10:06 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		   	  Quote: 	
		   	  Quote: 	
		   	  Quote: 	
		   If you're willing to have an always hot feeder to a starter contactor . . . 	
That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage. That is not the case, with the master off you will not be able to crank as the coil circuit for starter contactor will not be powered.  See dwg. 	
	


	


You're correct, sorry I spoke before i took a look at the actual circuit.

Sacha

Ps.  What is the issue with wether the prop windmills or stops?  Is it that the engine is easier to restart if the prop is windmilling?   

 [quote][b]

uuccio(at)gmail.com
Guest

Posted: Sun Oct 27, 2013 10:06 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		  >> That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage.

> 

>   There are TWO inputs to a starter contactor.

>   FAT wire power to operate the motor and

>   small wire power through the starter switch

>   to energize the contactor coil. One COULD

>   consider an always hot FAT wire that bypasses

>   the battery contactor while shutting down

>   the power source for the starter push-button.

>   But this is contrary to legacy design goals

>   for achieving max-dark on an electrical system

>   when all switches are OFF.

> 


	


Got it, thanks!

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