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kenryan

Joined: 20 Oct 2009
Posts: 429

Posted: Fri Aug 22, 2014 8:51 am Post subject: Z-19 Function

With FlyEFII's Bus Manager/Relay system when a loss of pressure is detected (because of a voltage drop from the pressure sensor) the main pump is switched off and the auxiliary pump is switched on, along with their corresponding indicator lights.Â   



I would be interested in Robert Nuckoll's evaluation of this system with regards to reliability of keeping the fuel pumps pumping. PDF attached.



  On Fri, Aug 22, 2014 at 6:15 AM, Ed meyer <ed.meyer(at)outlook.com (ed.meyer(at)outlook.com)> wrote:

 	  Quote: 	
		         	  Quote: 	
		     >Why    automatic? Describe the flight configuration under which such a >system    would benefit you as a pilot.

	
 I have had an in flight fuel starvation event that was not resolved until  after a no power landing which was successful. I know from that experience that  a fog of confusion came over me and after replaying the event in my mind, I  could not recall the point that the aux fuel pump was turned on. I had been  through the drill many times to simulate an engine out emergency but I know for  me when it actually happened, I did not perform as well as I could/should have.  An automatic switching to the aux fuel pump could potentially take care of a  problem without me having to remember to do it in the event of the fog. Of  course I would want some indication of the switch occurring.

 Â 

    	  Quote: 	
		  



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jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Sat Aug 23, 2014 1:17 pm Post subject: Re: Z-19 Function

[quote="ed.meyer(at)outlook.com"] 	  Quote: 	
		     >Why    automatic? Describe the flight configuration under which such a >system    would benefit you as a pilot.

	
 I have had an in flight fuel starvation event that was not resolved until  after a no power landing which was successful. I know from that experience that  a fog of confusion came over me and after replaying the event in my mind, I  could not recall the point that the aux fuel pump was turned on. I had been  through the drill many times to simulate an engine out emergency but I know for  me when it actually happened, I did not perform as well as I could/should have.  An automatic switching to the aux fuel pump could potentially take care of a  problem without me having to remember to do it in the event of the fog. Of  course I would want some indication of the switch occurring.

  

    	  Quote: 	
		  [b] 	


Ed,

I had suggested a similar "foolproof" system to Bob N when installing my EFI system. And he responded the same as he responded to you. What benefit is there to have the system be "automatic"? When I thought about it, I had to conclude that it just seemed cool. So, with that, laziness kicked in and I found a sense of relief that I didn't have to figure out  another sub-system for my one-off Glasair/Franklin CDI ignition, EFI, installation.

Then on first flight/take-off, I had an engine sputtering at 800'. Because I was in the TO phase, TO/<1500' AGL protocol (both pumps-ON, both ignitions-ON) was pre-configured, so I didn't have to worry about choosing and switching to the Plan B device, interpret annunciator lights, or rely on electronics to switch to the appropriate pump. On my TO roll, I knew beforehand that my only option in a loss of power event would be fuel selection. Won't go into the embarrassing details, but the problem became glaringly obvious when I glanced at my two fuel selectors. And the problem got diagnosed and solved before my heart was all the way out of my mouth.

Back on the ground reflecting on it all, I recalled asking Bob about how to automate a pump switch-over in the event of pump failure and his response. I was really glad I took his advice and I recommend you do the same, notwithstanding your EFII's cool "feature". 

Oh yeah, when doing fast-taxi testing, be prepared to fly.  



John

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Sat Aug 23, 2014 1:25 pm Post subject: Re: Z-19 Function

[quote="ed.meyer(at)outlook.com"] 	  Quote: 	
		     >Why    automatic? Describe the flight configuration under which such a >system    would benefit you as a pilot.

	
 I have had an in flight fuel starvation event that was not resolved until  after a no power landing which was successful. I know from that experience that  a fog of confusion came over me and after replaying the event in my mind, I  could not recall the point that the aux fuel pump was turned on. I had been  through the drill many times to simulate an engine out emergency but I know for  me when it actually happened, I did not perform as well as I could/should have.  An automatic switching to the aux fuel pump could potentially take care of a  problem without me having to remember to do it in the event of the fog. Of  course I would want some indication of the switch occurring.

  

    	  Quote: 	
		  [b] 	


Ed,

I had suggested a similar "foolproof" system to Bob N when installing my EFI system. And he responded the same as he responded to you. What benefit is there to have the system be "automatic"? When I thought about it, I had to conclude that it just seemed cool. So, with that, laziness kicked in and I found a sense of relief that I didn't have to figure out  another sub-system for my one-off Glasair/Franklin CDI ignition, EFI, installation.

Then on first flight/take-off, I had an engine sputtering at 800'. Because I was in the TO phase, TO/<1500' AGL protocol (both pumps-ON, both ignitions-ON) was pre-configured, so I didn't have to worry about choosing and switching to the Plan B device, interpret annunciator lights, or rely on electronics to switch to the appropriate pump. On my TO roll, I knew beforehand that my only option in a loss of power event would be fuel selection. Won't go into the embarrassing details, but the problem became glaringly obvious when I glanced at my two fuel selectors. And the problem got diagnosed and solved before my heart was all the way out of my mouth.

Back on the ground reflecting on it all, I recalled asking Bob about how to automate a pump switch-over in the event of pump failure and his response. I was really glad I took his advice and I recommend you do the same, notwithstanding your EFII's cool "feature". 

Oh yeah, when doing fast-taxi testing, be prepared to fly   .

John

jmjones2000(at)mindspring
Guest

Posted: Sun Aug 24, 2014 6:27 pm Post subject: Z-19 Function

Bob,



I have been looking at the Z-13/8 Diagram and have a few questions.

With a Dual ECU, Dual COIL, and Dual Fuel Pump system (primary and secondary), is it recommended to use the 4-rectifier Diode bridge and dual feed all items from both the battery bus and the E-Bus (or main bus)?  Or is it acceptable to wire the Primary components to one bus and the Secondary components to the other bus?  

Thanks!

Justin

On Aug 22, 2014, at 8:50 AM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:

[quote]With FlyEFII's Bus Manager/Relay system when a loss of pressure is detected (because of a voltage drop from the pressure sensor) the main pump is switched off and the auxiliary pump is switched on, along with their corresponding indicator lights.   



I would be interested in Robert Nuckoll's evaluation of this system with regards to reliability of keeping the fuel pumps pumping. PDF attached.



  On Fri, Aug 22, 2014 at 6:15 AM, Ed meyer <ed.meyer(at)outlook.com (ed.meyer(at)outlook.com)> wrote:

 	  Quote: 	
		         	  Quote: 	
		     >Why    automatic? Describe the flight configuration under which such a >system    would benefit you as a pilot.

	
 I have had an in flight fuel starvation event that was not resolved until  after a no power landing which was successful. I know from that experience that  a fog of confusion came over me and after replaying the event in my mind, I  could not recall the point that the aux fuel pump was turned on. I had been  through the drill many times to simulate an engine out emergency but I know for  me when it actually happened, I did not perform as well as I could/should have.  An automatic switching to the aux fuel pump could potentially take care of a  problem without me having to remember to do it in the event of the fog. Of  course I would want some indication of the switch occurring.

  

    	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


	


 <Bus_Manager_Installation_Instructions.pdf>[b]

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Sun Aug 24, 2014 8:32 pm Post subject: Re: Z-19 Function

My post got scrambled. Hoping to have better luck this time.

I wrote:



Ed, 

I had suggested a similar "foolproof" system to Bob N when installing my EFI system. And he responded the same as he responded to you. What benefit is there to have the system be "automatic"? When I thought about it, I had to conclude that it just seemed cool. So, with that, laziness kicked in and I found a sense of relief that I didn't have to figure out another sub-system for my one-off Glasair/Franklin CDI ignition, EFI, installation. 

Then on first flight/take-off, I had an engine sputtering at 800'. Because I was in the TO phase, TO/<1500' AGL protocol (both pumps-ON, both ignitions-ON) was pre-configured, so I didn't have to worry about choosing and switching to the Plan B device, interpret annunciator lights, or rely on electronics to switch to the appropriate pump. On my TO roll, I knew beforehand that my only option in a loss of power event would be fuel selection. Won't go into the embarrassing details, but the problem became glaringly obvious when I glanced at my two fuel selectors. And the problem got diagnosed and solved before my heart was all the way out of my mouth. 

Back on the ground reflecting on it all, I recalled asking Bob about how to automate a pump switch-over in the event of pump failure and his response. I was really glad I took his advice and I recommend you do the same, notwithstanding your EFII's cool "feature". 

Oh yeah, when doing fast-taxi testing, be prepared to fly 

 

John

ed.meyer(at)outlook.com
Guest

Posted: Mon Aug 25, 2014 6:46 am Post subject: Z-19 Function

 	  Quote: 	
		     >I had to    conclude that it just seemed cool. So, with that, laziness >kicked in and I    found a sense of relief that I didn't have to >figure out another    sub-system for my one-off Glasair/Franklin CDI >ignition, EFI,    installation.

	
  

 Thanks for the insight John but I am still not quite getting the downside  of the automation other than a bit more complexity.  My emergency situation  was different than yours in that it was not just after departure but rather  after a power off let down and the power would not come back up with the  throttle. And, for me â€˜coolâ€™ has nothing to do with it. In my emergency  experience I know my thinking was not clear at the time therefore my performance  was not up to par (I would like to think I would do better but I know from  experience I didnâ€™t). I am just thinking that the automation could help to  eliminate a step that I would need to do manually IF I remember to do it while  my mind is somewhat jumbled with stuff like best glide speed, where to land if I  canâ€™t get it running again, etc. I found that I liked the automation idea and  would not have thought of it myself had I not read that it is a function built  into the Bus Manager that EFII offers. Having said that, I also like a lot about  Bobâ€™s Z13/8 system.

  

 Ed

  

  

   [quote][b]

kenryan

Joined: 20 Oct 2009
Posts: 429

Posted: Mon Aug 25, 2014 7:29 am Post subject: Z-19 Function

I think the auto switching is a great idea in theory. I also understand Bob Nuckoll's comment that it needs to be evaluated to determine whether what is gained is offset by what is lost. My problem is that I lack the expertise to do that evaluation.Â   



Bob Nuckoll's and Robert Paisley are both clearly well qualified individuals. Each has accomplished a great deal in the field of aviation. If I understand Bob Nuckoll's correctly, he feels that added failure modes outweigh any benefits. On the other hand, Robert Paisley is confident enough that he included it in the very component that he designed to insure that the prop keeps turning in an electrically dependent engine.

  



Tis a puzzlement.

Ken



On Mon, Aug 25, 2014 at 6:45 AM, Ed meyer <ed.meyer(at)outlook.com (ed.meyer(at)outlook.com)> wrote:

  [quote]     	  Quote: 	
		     >I had to    conclude that it just seemed cool. So, with that, laziness >kicked in and I    found a sense of relief that I didn't have to >figure out another    sub-system for my one-off Glasair/Franklin CDI >ignition, EFI,    installation.

	
 Â 

 Thanks for the insight John but I am still not quite getting the downside  of the automation other than a bit more complexity.Â  My emergency situation  was different than yours in that it was not just after departure but rather  after a power off let down and the power would not come back up with the  throttle. And, for me â€˜coolâ€™ has nothing to do with it. In my emergency  experience I know my thinking was not clear at the time therefore my performance  was not up to par (I would like to think I would do better but I know from  experience I didnâ€™t). I am just thinking that the automation could help to  eliminate a step that I would need to do manually IF I remember to do it while  my mind is somewhat jumbled with stuff like best glide speed, where to land if I  canâ€™t get it running again, etc. I found that I liked the automation idea and  would not have thought of it myself had I not read that it is a function built  into the Bus Manager that EFII offers. Having said that, I also like a lot about  Bobâ€™s Z13/8 system.

 Â 

 Ed

 Â 

 Â 

    	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


[b]

jmjones2000(at)mindspring
Guest

Posted: Mon Aug 25, 2014 7:34 am Post subject: Z-19 Function

The redundancy for the fuel pump can easily be built using a simple circuit with the use of a fuel pressure safety switch used by the automotive racing community. The one below is set to 30 psi and would work well for the efii system. With the use of a relay and this switch, you can have the standby pump automatically turn on if the primary pump pressure drops below 30 psi. 

JEGS Performance Products#555-11206



Fuel Pressure Safety Switch[*]Preset to 30 psi



 



On Aug 25, 2014, at 6:45, "Ed meyer" <ed.meyer(at)outlook.com (ed.meyer(at)outlook.com)> wrote:

[quote]     	  Quote: 	
		     >I had to    conclude that it just seemed cool. So, with that, laziness >kicked in and I    found a sense of relief that I didn't have to >figure out another    sub-system for my one-off Glasair/Franklin CDI >ignition, EFI,    installation.

	
  

 Thanks for the insight John but I am still not quite getting the downside  of the automation other than a bit more complexity.  My emergency situation  was different than yours in that it was not just after departure but rather  after a power off let down and the power would not come back up with the  throttle. And, for me â€˜coolâ€™ has nothing to do with it. In my emergency  experience I know my thinking was not clear at the time therefore my performance  was not up to par (I would like to think I would do better but I know from  experience I didnâ€™t). I am just thinking that the automation could help to  eliminate a step that I would need to do manually IF I remember to do it while  my mind is somewhat jumbled with stuff like best glide speed, where to land if I  canâ€™t get it running again, etc. I found that I liked the automation idea and  would not have thought of it myself had I not read that it is a function built  into the Bus Manager that EFII offers. Having said that, I also like a lot about  Bobâ€™s Z13/8 system.

  

 Ed

  

  

    	  Quote: 	
		  



===================================

st">http://www.matronics.com/Navigator?AeroElectric-List

===================================

cs.com

===================================

matronics.com/contribution

===================================



	


[b]

kleh(at)dialupatcost.ca
Guest

Posted: Mon Aug 25, 2014 8:37 am Post subject: Z-19 Function

Providing you are notified when the system activates, and providing the 

system can not fail in any manner such that it blows the fuse or 

prevents manual pump activation (difficult to achieve), then a remaining 

risk is that the auto system increases the chance of the pump activating 

during a crash. Auto pump shutdown when the engine stops is considered a 

safety issue and all cars have that feature.



I don't have strong feelings either way and could fairly easily add a 

comparator to my existing pressure sensor but I have no plans to do so. 

For EFI pumps I believe that a larger safety increase is achieved just 

by using oem automotive filter socks in the fuel tank (or in the header 

tank in my case) to significantly reduce pump failures.



Ken



On 25/08/2014 11:32 AM, Justin Jones wrote:

 	  Quote: 	
		   The redundancy for the fuel pump can easily be built using a simple

 circuit with the use of a fuel pressure safety switch used by the

 automotive racing community. The one below is set to 30 psi and would

 work well for the efii system. With the use of a relay and this switch,

 you can have the standby pump automatically turn on if the primary pump

 pressure drops below 30 psi.



 JEGS Performance Products#555-11206

 # Fuel Pressure Safety SwitchPreset to 30 psi

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 25, 2014 8:38 am Post subject: Z-19 Function

At 10:28 AM 8/25/2014, you wrote:

  	  Quote: 	
		  I think the auto switching is a great idea in theory. I also understand Bob Nuckoll's comment that it needs to be evaluated to determine whether what is gained is offset by what is lost. My problem is that I lack the expertise to do that evaluation. 	


    At 10:28 AM 8/25/2014, you wrote:

 I think the auto switching is a great idea in theory. I also understand Bob Nuckoll's comment that it needs to be evaluated to determine whether what is gained is offset by what is lost. My problem is that I lack the expertise to do that evaluation.



  I suggest that you DO have that expertise . . .

 

  Consider the loss of engine at low altitude due to  failure of main fuel pump. Question:

 

  Does checklist call for running both main and aux  pumps during low altitude ops? If not, should it?

 

  Upgrading the level of technology in your airplane  is driven by a reason. Obviously, a single-pilot  IFR operation is less risky if the airplane is  fitted with an autopilot. Risk also goes down when  primary flight instruments (gyros) were backed up  with secondary instruments (needle-ball-airspeed).  This is part of the failure modes effects analysis  that drives the setting requirements, training, practice  and maintenance that go to reduction of risk.

 

  What was root cause in the case of the 'missing fuel  pump'? Adding an autopilot to offset pilot work-load  for managing a constellation of tasks is a no-brainer.  But hundreds of thousands of airplanes have been  fitted with multiple fuel pumps for nearly a century  . . . none of which were operated by anything more  than some switch on the panel that was managed (along  with lots of other things) by pilot inputs cited in  the POH and/or checklist.

 

  Okay, what are the work-load circumstances when  the pumps are to be switched on or off? 

 

  ON before takeoff and OFF after reaching comfortable  altitude . . .

 

  -AND- 

 

  ON before landing and OFF after leaving the active  runway.

 

  The thrust of my reasoning goes to abrogation of  duties that pilots have been expected to perform  for decades. What new taxation of a pilot's time,  attention and resources drives first a decision  to automate the fuel pump management in the first  place . . . and then recommend it to others as  a good and useful thing to do?

 

  "Aw shucks Nuckolls . . . it's JUST the fuel pumps  . . ."

 

  Agreed . . . but if JUST the fuel pumps  can be mis-managed contrary to POH or checklist,  are there OTHER features of legacy pilot duties  at similar risk?

 

  It isn't JUST the fuel pumps. It's about systems  integration  and operation that goes to the simplest,  lightest, lowest cost method for meeting requirements  while reducing unrealistic taxation of pilot time  and attention. It would be unrealistic to recommend  that pilots carry scientific calculators and perform  the spherical trigonometry  to navigate . . .  but entirely rational to push those tasks off onto  a $200 hand-held GPS. At the other end of the spectrum,  consider the data points from a century of lessons  learned for operating that second pump switch with  electro-smarts. That new, "time saving, safety enhancement"  now needs to be fitted with failure alarms and/or a  methodology for pre-flight testing. Whoops! There's that  pesky checklist again. Seems that a two-pump system  should be checked for integrity during start up with  the aux pump left ON until comfortable altitude is  achieved.

 



  What are the hazards for leaving an AUX pump ON?  Back in the day, many aux pumps were the Bendix  'thumpers' that featured a coil operated through  hard contacts that arced and wore out. Today,  those pumps have been replace with all solid state  devices having essentially ZERO wear.

 



   http://tinyurl.com/knsz7y9

 



  If the aux pump is operated in parallel with a main pump for  some phases of operation, then risk for having  the AUX pump on all the time are probably zero.  But you STILL need to independently confirm operation  of each pump during pre-flight which is a check-list  driven activity.

 

  This goes beyond 'keeping the engine running'. It goes  to reduction of risk with an optimal marriage  of pilot and machine. A machine that generally performs as  advertised every time when operated per the instruction  manual.

 



  Bob . . .      [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Aug 25, 2014 8:52 am Post subject: Z-19 Function

At 10:32 AM 8/25/2014, you wrote:

 	  Quote: 	
		  The redundancy for the fuel pump can easily be built using a simple 

circuit with the use of a fuel pressure safety switch used by the 

automotive racing community. The one below is set to 30 psi and 

would work well for the efii system. With the use of a relay and 

this switch, you can have the standby pump automatically turn on if 

the primary pump pressure drops below 30 psi.


	




I've never experienced a main pump failure but I've

run many a tank dry. The time that it took to move a valve

didn't cost a couple hundred feet of altitude.



In other words, if your check list already calls for

operation of both pumps at low altitude, what hazard is

being mitigated with auto-switching at higher altitudes?



   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Mon Aug 25, 2014 3:24 pm Post subject: Re: Z-19 Function

From the EFII Bus Manager manual: 	  Quote: 	
		  Fuel Pump Mode Switch 

This switch has two positions and determines the fuel pump drive operation of the Bus Manager. When in position â€œ1/Autoâ€ (the normal operating position), fuel pump 1 will be running and operating the engine. The Bus Manager will continuously monitor the fuel rail pressure by tapping into the signal wire from the fuel pressure sender that is connected to your engine monitor. If the fuel rail pressure drops below a precalibrated limit, the bus Manager will automatically turn on fuel pump 2. When in position â€œ2â€, fuel pump 2 is forced ON and fuel pump 1 will be turned OFF. Wire the Fuel Pump Mode Switch to the control harness as shown on DRAWING 2. 	


Is there a failure mode of the DFII that could result in the unwanted shutting off of a fuel pump?  I am not saying that could happen, just saying that unexpected things could happen if the pilot is not very familiar with automatic systems.  Regardless of the electrical system architecture, the builder needs to ask, "If this part fails, how will I know it, what are the consequences, and what is my plan B?"

Joe

_________________
Joe Gores

ed.meyer(at)outlook.com
Guest

Posted: Tue Aug 26, 2014 6:34 am Post subject: Z-19 Function

 	  Quote: 	
		     >If the aux    pump is operated in parallel with a main pump for some >phases of    operation, then risk for having the AUX pump on all the >time are probably    zero. But you STILL need to independently confirm >operation of each pump    during pre-flight which is a check-list driven    >activity.

	
 Now this is an idea that I had not considered. I have been used to the  procedures as mentioned where the aux pump was turned on for takeoff and landing  and off the rest of the time. The notion of simply leaving both pumps on all the  time makes a lot of sense and is certainly simple. 

  

 As always, thanks to everyone who chimed in. Has been a great  discussion.

  

 Ed

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Aug 26, 2014 7:39 am Post subject: Z-19 Function

At 09:34 AM 8/26/2014, you wrote:

 If the aux pump is operated in parallel with a main pump for some >phases of operation, then risk for having the AUX pump on all the >time are probably zero. But you STILL need to independently confirm >operation of each pump during pre-flight which is a check-list driven >activity.



  Now this is an idea that I had not considered. I have been used to the procedures as mentioned where the aux pump was turned on for takeoff and landing and off the rest of the time. The notion of simply leaving both pumps on all the time makes a lot of sense and is certainly simple.    As always, thanks to everyone who chimed in. Has been a great discussion.

 



   The next line of reasoning for this protocol is to make sure that you have a process by which the pumps are tested independently of each other before take-off.  It also behooves you to have independent power supply paths for the two pumps so no single failure takes down both pumps. 

     Bob . . .    [quote][b]

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Tue Aug 26, 2014 9:50 am Post subject: Re: Z-19 Function

[quote="ed.meyer(at)outlook.com"] 	  Quote: 	
		     >If the aux    pump is operated in parallel with a main pump for some >phases of    operation, then risk for having the AUX pump on all the >time are probably    zero. But you STILL need to independently confirm >operation of each pump    during pre-flight which is a check-list driven    >activity.

	
 Now this is an idea that I had not considered. I have been used to the  procedures as mentioned where the aux pump was turned on for takeoff and landing  and off the rest of the time. The notion of simply leaving both pumps on all the  time makes a lot of sense and is certainly simple. 

  

 As always, thanks to everyone who chimed in. Has been a great  discussion.

  

 Ed

    	  Quote: 	
		  [b] 	




Hi Ed,

The fuel pump system operation on my all-electric plane was intended to emulate legacy systems in low-wing carburetor planes that I trained in, that mandated "aux" pump ON during TO/Ldg and/or <1500' AGL. I considered the design of both pumps always on, but didn't like the idea of both pumps wearing at the same rate and possibly failing at the same time. Not likely, but I like confirming that both pumps are working to spec pressure on the ground and shutting the designated "aux"  pump off after reaching a pre-determined AGL floor. As the two are also wired to different busses, I feel I truly have a reserve pump that way. 

After handily managing my first-TO brain-fart with this system, more than ever I'm convinced of it's mission effectiveness, which is largely due to its simplicity. Not withstanding my confidence in solid-state electronics and being enamored of the new , I couldn't make the case for changing it.

My $.02

Hope this helps in your decision.



John

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Tue Aug 26, 2014 3:48 pm Post subject: Re: Z-19 Function

All Van's RV-12 E-LSA and S-LSA aircraft have two fuel pumps that run continuously.  There is no fuel pump switch to forget to turn on.  After turning on the master, the fuel pressure is noted with just the electric pump running.  After engine start, the pilot notes the fuel pressure increase with the mechanical engine driven pump also operating.

Joe

_________________
Joe Gores

jwd3ca(at)gmail.com
Guest

Posted: Wed Aug 27, 2014 5:13 am Post subject: Z-19 Function

just out of curiosity, Joe, what are those two fuel pressures, respectively? In pounds per square inch? Thanks!



On 26 August 2014 19:48, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

  

 All Van's RV-12 E-LSA and S-LSA aircraft have two fuel pumps that run continuously.Â  There is no fuel pump switch to forget to turn on.Â  After turning on the master, the fuel pressure is noted with just the electric pump running.Â  After engine start, the pilot notes the fuel pressure increase with the mechanical engine driven pump also operating.

  Joe

 

 --------

 Joe Gores

 

 

 

 

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Regards, Â J.

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

J. Davis, Â Â 

email: jwd3ca at gmail dot com

*NIX consulting, Medical Imaging research programming

 

- Zenith STOL CH750 C-FJNJ:Â Jab 3300, Whilrwind GA prop, AeroCarb

- Sonex #325 (ex)C-FJNJ, Jab 3300a, Prince P-Tip, Aerocarb

- former C-IGGY CH701 owner/builder

- see these and more at http://cleco.ca

 



 

  [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Wed Aug 27, 2014 10:12 am Post subject: Re: Z-19 Function

 	  Quote: 	
		  just out of curiosity, Joe, what are those two fuel pressures, respectively? In pounds per square inch? Thanks! 	


RV-12 fuel pressure with electric pump only is about 3 psi.   With the engine driven pump also running the pressure goes up to about 4 psi.  The fuel pressure senders are not known for accuracy.  I pay more attention to the change in pressure, not the actual numbers.

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Aug 27, 2014 11:49 am Post subject: Z-19 Function

At 08:11 AM 8/27/2014, you wrote:

 just out of curiosity, Joe, what are those two fuel pressures, respectively? In pounds per square inch? Thanks!



 

 On 26 August 2014 19:48, user9253 <fransew(at)gmail.com> wrote:

 --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 All Van's RV-12 E-LSA and S-LSA aircraft have two fuel pumps that run continuously.ÂThere is no fuel pump switch to forget to turn on.ÂAfter turning on the master, the fuel pressure is noted with just the electric pump running.ÂAfter engine start, the pilot notes the fuel pressure increase with the mechanical engine driven pump also operating.

 Joe



  There you go. Two nails, one hammer, all operations independently verifiable before take off. Sounds like he's zeroing in on the elegant fuel delivery system.

 

  The 'putt-putt' style fuel pumps took a quantum jump forward with elimination of hard contacts to pulse the motor. You can't 'hurt' these pumps by blocking them off . . . they're inherently pressure limited by the size of a spring that gets compressed during each power-stroke.

 

  While current draw is kind of 'peaky', the ENERGY consumed by these pumps is nominal and goes down during reduced flow rates.

 

  Simple, low parts count, very low wear rates to moving parts, no highly stressed electrical parts. Works good, lasts a long time and costs a pittance.

 



  . . . an evolutionary progression forward that requires no more hardware or operational attention than grandpa's Cherokee.

 

    Bob . . .    [quote][b]

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