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Z-14 for electrically dependent engine

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ceengland7(at)gmail.com
Guest

Posted: Sun Feb 02, 2020 8:24 am Post subject: Z-14 for electrically dependent engine

On 2/2/2020 9:17 AM, Krea Ellis wrote:

 	  Quote: 	
		   



 Again, apologies for having to use email to post to the forum.  Iâ€™ve registered and reached out to Matt a couple of times, but I still cannot log in and post directly. Most of my emails bounce back too - although it appears someone is receiving them.



 Mr. Nuckolls and the others posting - thank you for your continued input on the work we are all attempting for a safe implementation of a redundant and/or reliable electrical system for our electrically dependent engines.



 I really appreciate the lack of comments like â€œjust install magnetos or pMags and mechanical fuel injectionâ€ somewhat common on other forums.



 Here are a couple of points and questions that may have been covered, but I would like to reiterate.



 1.  At least with SDS on the 6 cylinder installations, providing independent power sources to the fuel pumps, coil packs and ECUâ€™s is very straightforward using the Z-14 architecture. Confirmation of proper operation of each component prior to flight is also easily carried out.

 2.  As there is no redundancy with the fuel injectors and since they are powered by the airframe, independent, redundant power is more difficult and/or complex. Loss of an injector (or bank of injectors) is easily determined at any time, but difficult to remedy during flight. Good news is that the injectors are very reliable (assuming competent installation).

 3.  A dual bus fed diode protected engine or injector bus violates the very â€œpureâ€ separation that exists in Z-14, but as of right now - there are no dual power source alternatives of which I am aware. I am using the term â€œpower sourceâ€ as a single battery and alternator fed bus.

 4.  A single bus could be utilized for all injectors, but would provide no alternative in the event of a loss of that one main bus. This would be the simplest approach I believe, but provides less redundancy. Also less potential failure points, but which bus of the two available do you use?



 I am working with the folks at SDS on a scheme for providing a passive power path to the injectors with each bank being fed independently and alternate paths (using a more complex arrangement) to switch all injectors to one bus or the other if needed due to the loss of one bus or the other. The downside of this approach will clearly be additional components that will have failure points. The counter to that these components will likely be very similar to those already used and tested by SDS for the injector signal paths. Loss of signal (ground) paths or loss of power is equally problematic in any SDS type installation.



 More info to come hopefully later this week from SDS and I continue to lose sleep over this issue.  Probably overthinking this and as I have to remind myself - we are not building Part 25 Transport Category Airplanes.



 Thank you!



 Krea Ellis

Hi Krea,
	




1st, I have *always* used email for this list/forum. When it started, 

there was no forum format; it was purely email exchanges with an archive 

of the emails. I realize that it isn't exactly '21st century', but it 

can have the advantage of being able to retain a record of important 

emails on members' local systems. So if you can post via email, roll 

with it.



On your concerns about various engine bus redundancies: FWIW, when I 

struggled with designing my alt engine stuff and ran into a seemingly 

insurmountable issue/conflict, I eventually would come back to looking 

at what's been done for decades in 'traditional' engine systems. I came 

to realize that there is a single fuel delivery system, and while there 

is a backup fuel pump, almost all traditional installations have failure 

modes where *either* pump could fail the entire fuel delivery system. 

Only the ignition system is truly redundant (and with the old 'dual mag' 

modules, even that can be doubtful).



I finally realized that with reasonable 'best practices' when installing 

the engine bus (which is simply a ATC fuse block), there just isn't 

anything that can cause the bus itself, in its entirety, to fail. The 

only thing that could bring down the entire bus would be the supply to 

the bus. A 2nd source of power to the bus remedies that issue. If the 

single 10-32 stud feeding the bus is a real concern, the most common ATC 

fuse bus is relatively easy to modify to add a 2nd 10-32 stud at the 

other end of the bus.



With all my engine 'stuff' on one engine bus, backup is now down to 

flipping one, or at most two, switches. Whenever I'm pondering 

multi-step, multi-layer troubleshooting in the air, I try to remember 

the highly trained multi-person airline crew that flew an airliner into 

the ground while running through checklists and flipping breakers. The 

biggest thing that bothers me about my alt engine installation is the 

more complex switchology and significant operational differences from 

the systems I (and everyone else) have spent decades flying.



You're not going to be comfortable with your system until you're 

comfortable with it. But it might be worth stepping back and looking 

'big picture' for a bit. Checking every detail should happen, but 

sometimes our initial premise may need re-evaluation. There are one or 

two of my basic premises I'm currently rethinking a bit....



Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Feb 02, 2020 9:34 am Post subject: Z-14 for electrically dependent engine

 	  Quote: 	
		  

 3.  A dual bus fed diode protected engine or injector bus violates the very â€œpureâ€ separation that exists in Z-14, but as of right now - there are no dual power source alternatives of which I am aware. I am using the term â€œpower sourceâ€ as a single battery and alternator fed bus. 

 4.  A single bus could be utilized for all injectors, but would provide no alternative in the event of a loss of that one main bus. 	


   How would that happen? EVERY branch feeder in Z-14

   is QUAD sourced until some component fails in flight

   (an exceedingly rare event). Two distribution

   busses (main and aux) remain at least DUAL sourced

   and sometimes TRIPLE sourced depending on nature of failure.



   Complete loss of power on either bus just doesn't

   happen . . . Z-12 (revised) is another solid

   option where a single bus is TRIPLE fed and no

   less than DUAL fed after loss of a single

   component.



     

  	  Quote: 	
		   This would be the simplest approach I believe, but provides less redundancy. Also less potential failure points, but which bus of the two available do you use? 	


   take your pick . . . it doesn't matter.



 

  	  Quote: 	
		  I am working with the folks at SDS on a scheme for providing a passive power path to the injectors with each bank being fed independently and alternate paths (using a more complex arrangement) to switch all injectors to one bus or the other if needed due to the loss of one bus or the other.The downside of this approach will clearly be additional components that will have failure points. The counter to that these components will likely be very similar to those already used and tested by SDS for the injector signal paths. Loss of signal (ground) paths or loss of power is equally problematic in any SDS type installation. 



 More info to come hopefully later this week from SDS and I continue to lose sleep over this issue.  Probably overthinking this and as I have to remind myself - we are not building Part 25 Transport Category Airplanes. 	




   Can you suggest that SDS contact me with a

   goal of collaborating on a unified approach

   to minimizing risks?



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Feb 02, 2020 9:39 am Post subject: Z-14 for electrically dependent engine

 	  Quote: 	
		  

 1st, I have *always* used email for this list/forum. When it started, there was no forum format; it was purely email exchanges with an archive of the emails. I realize that it isn't exactly '21st century', but it can have the advantage of being able to retain a record of important emails on members' local systems. So if you can post via email, roll with it. 	


   I have always used the email portal except when

   participating away from the office . . . perhaps

   on a computer not belonging to me.



   Threads are seamless, locally archived and easy

   to trim. I have copies of threads going back about

   15 years that are easily searched for content.



 

   Bob . . .

Randy C-GRPY

Joined: 21 Apr 2018
Posts: 26

Posted: Sun Feb 02, 2020 12:23 pm Post subject: Re: Z-14 for electrically dependent engine

 	  nuckolls.bob(at)aeroelect wrote: 	
		   	  Quote: 	
		  

 3.  A dual bus fed diode protected engine or injector bus violates the very â€œpureâ€ separation that exists in Z-14, but as of right now - there are no dual power source alternatives of which I am aware. I am using the term â€œpower sourceâ€ as a single battery and alternator fed bus. 

 4.  A single bus could be utilized for all injectors, but would provide no alternative in the event of a loss of that one main bus. 	


   How would that happen? EVERY branch feeder in Z-14

   is QUAD sourced until some component fails in flight

   (an exceedingly rare event). Two distribution

   busses (main and aux) remain at least DUAL sourced

   and sometimes TRIPLE sourced depending on nature of failure.



   Complete loss of power on either bus just doesn't

   happen . . . Z-12 (revised) is another solid

   option where a single bus is TRIPLE fed and no

   less than DUAL fed after loss of a single

   component.



     

  	  Quote: 	
		   This would be the simplest approach I believe, but provides less redundancy. Also less potential failure points, but which bus of the two available do you use? 	


   take your pick . . . it doesn't matter.



 

  	  Quote: 	
		  I am working with the folks at SDS on a scheme for providing a passive power path to the injectors with each bank being fed independently and alternate paths (using a more complex arrangement) to switch all injectors to one bus or the other if needed due to the loss of one bus or the other.The downside of this approach will clearly be additional components that will have failure points. The counter to that these components will likely be very similar to those already used and tested by SDS for the injector signal paths. Loss of signal (ground) paths or loss of power is equally problematic in any SDS type installation. 



 More info to come hopefully later this week from SDS and I continue to lose sleep over this issue.  Probably overthinking this and as I have to remind myself - we are not building Part 25 Transport Category Airplanes. 	




   Can you suggest that SDS contact me with a

   goal of collaborating on a unified approach

   to minimizing risks?



 

   Bob . . . 	




I emailed Ross with your generous offer Bob.



Randy

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 04, 2020 1:29 pm Post subject: Z-14 for electrically dependent engine

 	  Quote: 	
		  I am working with the folks at SDS on a scheme for providing a passive power path to the injectors with each bank being fed independently and alternate paths (using a more complex arrangement) to switch all injectors to one bus or the other if needed due to the loss of one bus or the other. 	


  Poked around on the SDS website for a few minutes and

  found this:



 Disadvantages of SDS vs. Conventional

 Aircraft Engine SystemsThe big disadvantage of EFI compared to a carb or mechanical

 injection and magnetos is that electrical power is required for

 the pump, computer, ignition and injectors. The likelihood of

 both the alternator and battery failing simultaneously is

 practically zero with standard aircraft maintenance procedures.

 Generally, a good battery will allow you to keep essentials powered

 for 20-90 minutes after an alternator failure permitting diversion

 to another airport. We consider proper gauges and/or warning

 lights to indicate an alternator failure to be very important.

 We have an ammeter, voltmeter, low voltage warning light and

 buzzer now on our RV6A and also added a backup battery in Feb. 2005. 



 [img]cid:.0[/img][/i][/b]

 

 

   I don't see anything that argues with the ideas

   and architecture philosophies we've been discussing

   here over the last week or so.

   

   Their assertions as to component reliability combined

   with the block diagram above illustrating everything

   running from a 'reliable' bus confirms their

   confidence in what's been recommended here on the

   List in terms of insuring a supply of DC power.



   I think the drawing above could

   be 'cleaned up' a tad and may have an error 

   about the injector selector switch wiring . . .

   but I think the spirit and intent of the

   SDS is clear and raises no flags at this

   time. It also confirms my suggestion that

   running the entire SDS system from either

   main or aux bus of Z-14 or the main bus

   of Z-12 offers a level of redundancy

   I think I could sell onto a TC aircraft.



   I'm getting ready to hit the asphalt on a trip

   to visit family in Cincinatti so I'll be off-line

   until Sunday.

 

   Bob . . .

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ceengland7(at)gmail.com
Guest

Posted: Tue Feb 04, 2020 1:48 pm Post subject: Z-14 for electrically dependent engine

On 2/4/2020 3:25 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		                

          	  Quote: 	
		  I am working with           the folks at           SDS on a scheme for providing a passive power path to the           injectors with           each bank being fed independently and alternate paths (using a           more           complex arrangement) to switch all injectors to one bus or the           other if           needed due to the loss of one bus or the other. 	
         

          Poked around on the SDS website for a few minutes and

          found this:

         

              Disadvantages of SDS vs. Conventional

           Aircraft Engine Systems       The big disadvantage             of EFI compared to a carb or mechanical

             injection and magnetos is that electrical power is required             for

             the pump, computer, ignition and injectors. The likelihood             of

             both the alternator and battery failing simultaneously is

             practically zero with standard aircraft maintenance             procedures.

             Generally, a good battery will allow you to keep essentials             powered

             for 20-90 minutes after an alternator failure permitting             diversion

             to another airport. We consider proper gauges and/or warning

             lights to indicate an alternator failure to be very             important.

             We have an ammeter, voltmeter, low voltage warning light and

             buzzer now on our RV6A and also added a backup battery in             Feb. 2005.             

             

           [img]cid:part1.957EE1DE.10DEB7F4(at)gmail.com[/img]

         

         

           I don't see anything that argues with the ideas

           and architecture philosophies we've been discussing

           here over the last week or so.

           

           Their assertions as to component reliability combined

           with the block diagram above illustrating everything

           running from a 'reliable' bus confirms their

           confidence in what's been recommended here on the

           List in terms of insuring a supply of DC power.

         

           I think the drawing above could

           be 'cleaned up' a tad and may have an error 

           about the injector selector switch wiring . . .

           but I think the spirit and intent of the

           SDS is clear and raises no flags at this

           time. It also confirms my suggestion that

           running the entire SDS system from either

           main or aux bus of Z-14 or the main bus

           of Z-12 offers a level of redundancy

           I think I could sell onto a TC aircraft.

         

           I'm getting ready to hit the asphalt on a trip

           to visit family in Cincinatti so I'll be off-line

           until Sunday.

                

             Bob . . .             	
     To (possibly over-) emphasize, quoting from above:

     

     It also confirms my suggestion that

           running the entire SDS system from either

           main or aux bus of Z-14 or the main bus

           of Z-12 offers a level of redundancy

           I think I could sell onto a TC aircraft.

         

       The injector control scheme, and the       fact that the injectors are not redundant (two injectors per       cylinder) seems to be what is creating the heartburn. I think I've       been saying something similar; all engine stuff on one bus, with       controllable redundant sources of power. It is, after all, what       SDS recommends.

       

       Charlie

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 04, 2020 3:04 pm Post subject: Z-14 for electrically dependent engine

 	  Quote: 	
		  

 The injector control scheme, and the fact that the injectors are not redundant (two injectors per cylinder) seems to be what is creating the heartburn. I think I've been saying something similar; all engine stuff on one bus, with controllable redundant sources of power. It is, after all, what SDS recommends. 	


   Agreed.  No 'enhancements' are recommended

   or useful. 



 

   Bob . . .

adamb

Joined: 04 Feb 2020
Posts: 1

Posted: Tue Feb 04, 2020 4:57 pm Post subject: Re: Z-14 for electrically dependent engine

 	  nuckolls.bob(at)aeroelect wrote: 	
		   	  Quote: 	
		  

 The injector control scheme, and the fact that the injectors are not redundant (two injectors per cylinder) seems to be what is creating the heartburn. I think I've been saying something similar; all engine stuff on one bus, with controllable redundant sources of power. It is, after all, what SDS recommends. 	


   Agreed.  No 'enhancements' are recommended

   or useful. 



 

   Bob . . . 	




So suppose there's smoke in the cockpit, not sure where it's coming from. A trained response is to shut off the master (both masters in the case of Z14). If the SDS stuff is on either the main or Aux busses and the masters are switched off, the engine shuts off... 



I'd rather the SDS components be on the battery busses to prevent this. 

This is the primary reason for my plan to power the ECUs, Fuel pumps, and Coils from their respective battery busses (there are 2 of each so one is fed from main battery bus and the other from aux battery bus). And provide a diode OR'ed Injector bus from the battery busses to power the injectors. 

Others have taken the approach of feeding all components off of a "Engine bus" redundantly powered from battery busses. 



Maybe I'm missing something, but I'm very uncomfortable not being able to shut off the master switches and keep the engine running. 



Adam

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Tue Feb 04, 2020 6:42 pm Post subject: Re: Z-14 for electrically dependent engine

I agree with you Adam.  The pilot should be able to shut off all sources of

electrical power at the source.  Putting relays (independent of the battery 

contactor) between the batteries and engine bus accomplishes that.  In case 

of smoke in the cockpit, most pilots would shut off the master switch first, 

expecting the engine to keep running.  If the smoke gets bad enough, then 

electrical power to the engine bus can be shut off along with the fuel valve.

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Tue Feb 04, 2020 6:42 pm Post subject: Z-14 for electrically dependent engine

On 2/4/2020 6:57 PM, adamb wrote:

 	  Quote: 	

 nuckolls.bob(at)aeroelect wrote:

>>   The injector control scheme, and the fact that the injectors are not redundant (two injectors per cylinder) seems to be what is creating the heartburn. I think I've been saying something similar; all engine stuff on one bus, with controllable redundant sources of power. It is, after all, what SDS recommends.

>     Agreed.  No 'enhancements' are recommended

>     or useful.

>

>   

>     Bob . . .

 So suppose there's smoke in the cockpit, not sure where it's coming from. A trained response is to shut off the master (both masters in the case of Z14). If the SDS stuff is on either the main or Aux busses and the masters are switched off, the engine shuts off...

 I'd rather the SDS components be on the battery busses to prevent this.

 This is the primary reason for my plan to power the ECUs, Fuel pumps, and Coils from their respective battery busses (there are 2 of each so one is fed from main battery bus and the other from aux battery bus). And provide a diode OR'ed Injector bus from the battery busses to power the injectors.

 Others have taken the approach of feeding all components off of a "Engine bus" redundantly powered from battery busses.

 Maybe I'm missing something, but I'm very uncomfortable not being able to shut off the master switches and keep the engine running.

 Adam

That's what I did, though my system is dual alt/single battery. Engine 

(all of it) is on one switched 'hot' bus, that can also be fed from the 

main a/c bus. Smoke emergency would be just like a traditional 

installation; master off & the motor keeps turning.

Charlie

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