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Z-14 implementation for electrically dependent engine

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 27, 2020 10:20 am Post subject: Z-14 implementation for electrically dependent engine

At 06:08 AM 1/27/2020, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Krea Ellis <krea.ellis(at)gmail.com>



 First post. Thanks for considering my dilemma.



 Installing dual ECU SDS fuel injection and ignition on a 6 cylinder Lycoming on an RV-10.



 Design goal was for independent busses for each “channel” of SDS. Easy to achieve for fuel pumps, ECU’s and coil packs. Not easy for fuel injector power. In normal mode, each ECU only controls half (three) fuel injectors. Injectors are ground triggered by the ECU, power to all injectors comes from the airframe bus(ses), not the ECU’s. 



 Was trying to avoid have power for injectors going through a single switch. Other option is a diode fed/protected “injector bus” but this creates failure modes as well.



 So is power through an appropriately rated Honeywell TL switch more reliable/redundant than the diode fed bus? 



 Any other suggestions as to how to provide redundant power to all 6 fuel injectors?



 Thanks much!

 	


   What architecture are you considering?



 



 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 27, 2020 11:39 am Post subject: Z-14 implementation for electrically dependent engine

At 06:08 AM 1/27/2020, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Krea Ellis <krea.ellis(at)gmail.com>



 First post. Thanks for considering my dilemma.



 Installing dual ECU SDS fuel injection and ignition on a 6 cylinder Lycoming on an RV-10.



 Design goal was for independent busses for each “channel” of SDS. Easy to achieve for fuel pumps, ECU’s and coil packs. Not easy for fuel injector power. In normal mode, each ECU only controls half (three) fuel injectors. Injectors are ground triggered by the ECU, power to all injectors comes from the airframe bus(ses), not the ECU’s. 



 Was trying to avoid have power for injectors going through a single switch. Other option is a diode fed/protected “injector bus” but this creates failure modes as well.



 So is power through an appropriately rated Honeywell TL switch more reliable/redundant than the diode fed bus? 



 Any other suggestions as to how to provide redundant power to all 6 fuel injectors?



 Thanks much!

 	


   What architecture are you considering?



 



 

   Bob . . .

- The Matronics AeroElectric-List Email Forum -

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 27, 2020 11:44 am Post subject: Z-14 implementation for electrically dependent engine

 	  Quote: 	
		  

 Any other suggestions as to how to provide redundant power to all 6 fuel injectors?



 Thanks much! 	


   This is figure Z-14 . . . both main and

   aux busses are already quad redundant

   with virtually zero risk for total loss

   of power.



   Can you point us to a schematic/wiring

   diagram for the engine electrics?



 

 

   Bob . . .

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Randy C-GRPY

Joined: 21 Apr 2018
Posts: 26

Posted: Fri Jan 31, 2020 3:49 pm Post subject: Re: Z-14 implementation for electrically dependent engine

 	  nuckolls.bob(at)aeroelect wrote: 	
		   	  Quote: 	
		  

 Any other suggestions as to how to provide redundant power to all 6 fuel injectors?



 Thanks much! 	


   This is figure Z-14 . . . both main and

   aux busses are already quad redundant

   with virtually zero risk for total loss

   of power.



   Can you point us to a schematic/wiring

   diagram for the engine electrics?



 

 

   Bob . . . 	




SDS's schematic....

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Engine Bus.pdf

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johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Fri Jan 31, 2020 7:38 pm Post subject: Re: Z-14 implementation for electrically dependent engine

 	  Randy C-GRPY wrote: 	
		  



SDS's schematic.... 	




Hi Randy,



Some thoughts:



The SDS schematic leaves out a lot of details.

The ECU select switch is SPDT.

Since the ECUs are unswitched I don't understand how the crew can preflight whether the injector relays are working.

I would not "combine injector power on each bank".

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_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

Last edited by johnbright on Sat Feb 01, 2020 7:14 am; edited 1 time in total

Randy C-GRPY

Joined: 21 Apr 2018
Posts: 26

Posted: Sat Feb 01, 2020 8:09 am Post subject: Re: Z-14 implementation for electrically dependent engine

 	  johnbright wrote: 	
		   	  Randy C-GRPY wrote: 	
		  



SDS's schematic.... 	




Hi Randy,



Some thoughts:



The SDS schematic leaves out a lot of details.

The ECU select switch is SPDT.

Since the ECUs are unswitched I don't understand how the crew can preflight whether the injector relays are working.

I would not "combine injector power on each bank". 	




Ya, I have to admit that I don't know anything about the internal wiring of the relays or the ECU's. In the preflight I plan on cycling each power feed to the engine bus to make sure that both are working, I'd also cycle the ECU select between 1,2, and both.  The coils and fuel pumps would also be similarly checked. I would expect that if a relay or an ECU were unservicable that it would show up with those checks. Do you have a different opinion John?

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johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Sat Feb 01, 2020 9:21 am Post subject: Re: Z-14 implementation for electrically dependent engine

 	  Randy C-GRPY wrote: 	
		  ...I'd also cycle the ECU select between 1,2, and both... I would expect that if a relay or an ECU were unservicable that it would show up with those checks. Do you have a different opinion John? 	




Hi Randy,



You are using SDS dual ECU for six cylinder with fuel trim. I know the dual four cylinder wiring because I have the harness and relays. SDS does not show full schematic details in their install manuals. It looks to me as though the Normal injector switch position is relays not energized. Suppose the black wire to the common terminal of the SPDT switch was broken; engine would run in all three switch positions and pass preflight. Ref attached snip from "dual6ecurev3.pdf".

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dual6ecurev3 snip.jpg

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_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

Randy C-GRPY

Joined: 21 Apr 2018
Posts: 26

Posted: Sat Feb 01, 2020 1:53 pm Post subject: Re: Z-14 implementation for electrically dependent engine

 	  johnbright wrote: 	
		   	  Randy C-GRPY wrote: 	
		  ...I'd also cycle the ECU select between 1,2, and both... I would expect that if a relay or an ECU were unservicable that it would show up with those checks. Do you have a different opinion John? 	




Hi Randy,



You are using SDS dual ECU for six cylinder with fuel trim. I know the dual four cylinder wiring because I have the harness and relays. SDS does not show full schematic details in their install manuals. It looks to me as though the Normal injector switch position is relays not energized. Suppose the black wire to the common terminal of the SPDT switch was broken; engine would run in all three switch positions and pass preflight. Ref attached snip from "dual6ecurev3.pdf". 	




I'm not sure that I'm following correctly. That switch determines whether the injectors are running off of one or the other ECU or both (each taking three injectors). If you were on both and that wire were broken I'm not sure why the engine would continue to run normally.

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johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Sat Feb 01, 2020 3:34 pm Post subject: Re: Z-14 implementation for electrically dependent engine

 	  Randy C-GRPY wrote: 	
		  



I'm not sure that I'm following correctly. That switch determines whether the injectors are running off of one or the other ECU or both (each taking three injectors). If you were on both and that wire were broken I'm not sure why the engine would continue to run normally. 	




Hi Randy,



I don't have the relays and harness in hand to 100% verify but I imagine:The Normal injector switch position is relays not energized, three injectors on each ECU because an ECU can't individually drive six injectors so cylinder trim wouldn't work.

The Primary position energizes a relay to take three injectors off the backup ECU and put them on the primary ECU, injectors paralleled in pairs.

The Backup position energizes a relay to take three injectors off the primary ECU and put them on the backup ECU, injectors paralleled in pairs.





There is also a Mixture Knob Relay. Perhaps that disables cylinder trim.

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_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

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