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Fuel return line attachment point with 912UL
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Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Thu Apr 23, 2009 12:10 am Post subject: Fuel return line attachment point with 912UL

Karl,

  

 Personally, I would stick to the recommended fuel supply  configuration and fit two Floscan transducers as detailed in the LAA approved  mod.  This ensures a constant circulation of fuel in the length of pipe  that joins the two carbs together and avoids vapor locking as much as  possible.  If you are prepared to accept the slightly increased risk of  vapor locking, ( probably more likely in the future with the changes to Mogas)  you could modify the fuel system as described by Marcel and then you only need  one transducer.  My understanding is that this would require a new mod  approval but I do know that a number of aircraft are flying with this  arrangement having installed it under "standard aircraft practice" and they have  not reported any problems.

  

 Regarding the  location of the transducers, mine are in the engine compartment, well wrapped in  firesleeve, and have not given any problem.  Again, if you have the option  (Trigear) it is preferable to mount them outside the "hot" area.  

  

 The Floscan  transducer is also used in marine applications and you can buy the identical  part, at a "reduced" price, from  www.merlinequipment.com  in the  UK. - Still very expensive!

  

 Note that if  you are using a FS450 configured for a single transducer you will have to swap  it for a double transducer model.

  

 As usual, you  pays your money and takes your choice!

  

 Regards

  

 Brian

 



   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Karl  Heindl

Sent: 23 April 2009 01:25

To:  europa-list(at)matronics.com

Subject: RE: Fuel return line  attachment point with 912UL

 

   

Brian,

 

I believe it helps a lot, but I have to think about  it a little more. Are you saying that I can change my plumbing and not use a  transducer in the return line ? My fuel lines are as per factory recommendations  apart from gascolator and location of gascolator and fuel pump.

It would save  a great deal of money; the tr. is now $ 332.- from ACS. I took advantage of the  ACS discount plus the $ 175.- rebate from JPI, and payed 'only' $310 for the  complete FS450

single transducer kit. 

What then is the LAA recommendation  and what about Ian's mod submission to the LAA  ?

 

Cheers,    Karl



 



  

  From: bdavies(at)dircon.co.uk

To: europa-list(at)matronics.com

Subject: RE:  Fuel return line attachment point with 912UL

Date: Wed, 22 Apr  2009 19:12:24 +0100



 .ExternalClass .EC_hmmessage P { 	PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; PADDING-TOP: 0px } .ExternalClass BODY.EC_hmmessage { 	FONT-SIZE: 10pt; FONT-FAMILY: Verdana }   No Karl, you have not  missed anything.  If you install the fuel system as recommended by the  factory on a Rotax 921, you need two transducers so that the return flow is  subtracted from the total flow- leaving you with fuel consumption.  If you  change the fuel supply configuration so that the return line starts before the  fuel gets to the carbs, you can then have a single feed to the carbs.  The  fuel flow in this single feed is the fuel consumption of the  engine.

  

 Hope that helps.

  

 Brian Davies

  

   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Karl  Heindl

Sent: 22 April 2009 18:22

To:  europa-list(at)matronics.com

Subject: RE: Fuel return line  attachment point with 912UL

 

  Hi,

 

I am also very confused about what has been  said so far. I will be installing a FS450 fuel flow gadget, and it calls for  transducers in the flow and return lines. I am not interested in how much fuel  is flowing to the engine, I am interested in the fuel consumption. And that  consumption is the difference between flow and return. Have I missed something  ?

 

BTW, I am looking for another Floscan 201 A6 with a matching  K-factor.

 

Karl

 



  

 	  Quote: 	
		   From:  roberthatton1(at)googlemail.com

 To: europa-list(at)matronics.com

  Subject: RE: Fuel return line attachment point with 912UL

  Date: Wed, 22 Apr 2009 18:00:53 +0100

 

 --> Europa-List  message posted by: "Robert Hatton" <roberthatton1(at)googlemail.com>

  

 Hello Graham, 

 

 I am following this thread for I shall  also be looking at fitting a fuel

 flow meter. Could I ask you to  elaborate on your comment about ignoring the

 return flow for you are  only measuring the fuel to the engine. I think I

 understand that with  the placement of the Flowscan (from Marcel's the

 schematic) no problem  in measuring the fuel going to the engine. But with

 the fuel coming back  via the return line will that not eventually (after

 going through the  system) go back to the engine again via the Flowscan? The

 question  being, are the amounts so small not to worry about it and does this

 just  build in a safety margin? Sorry to sound thick on this, I am just

 trying  to get my head around what has been said so far and the schematic.

  

 

 Robert

 

 Robert Hatton

 email:  roberthatton1(at)googlemail.com

 US Cell: +01 303 906 9395

 UK  Mobile: +44 79 66 184171

 

 

 -----Original  Message-----

 From: owner-europa-list-server(at)matronics.com

  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Graham

  Singleton

 Sent: Wednesday, April 22, 2009 1:12 PM

 To:  europa-list(at)matronics.com

 Subject: Re: Fuel return line  attachment point with 912UL

 

 --> Europa-List message posted  by: Graham Singleton

 <grahamsingleton(at)btinternet.com>

  

 The question is, how does ignoring the return flow affect the  accuracy

 >> of the fuel flow instrument? It depends on the  quantity of the return

 >> flow of course. Is there any data about  this? Maybe in the rotax

 >> maintenance manuals?

 >>  

 >

 > That's indeed the question I so far have not found an  answer to. The

 > only thing I was told by different people is that  return flow varies

 > with RPM, but no hard numbers on return flow  have made it my way. So

 > basically I *know* there will be an  inaccuracy when ignoring return

 > flow, but *do not know* just how  large this inaccuracy is (hence my

 > attempt to come up with  something better for a single sender setup).

 >

 >  Marcel

 > 

 Marcel

 The return flow does not affect your  fuel flow to the engine and that is 

 what you are measuring. So you can  forget about it with this configuration

 Graham

 

 

  

 

 

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

&g=======
	


[quote]  

 

 

 	  Quote: 	
		  
	




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href="http://www.matronics.com/contribution">http://www.matronics.com/c

. Checked by AVG - www.avg.com  	  Quote: 	
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ronics.com
	


ww.matronics.com/contribution



	
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href="http://www.matronics.com/Navigator?Europa-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com

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kheindl(at)msn.com
Guest

Posted: Thu Apr 23, 2009 3:25 am Post subject: Fuel return line attachment point with 912UL

  

Brian and Marcel C

  

 Many thanks for responding to my questions. I am undecided and I think I will sit on this for a while. I have done all the preparatory work for the instrument and wiring. I may install the feed line transducer just aft of the mech. fuel pump C the engine is cool in that area. If I install a second tr. C then this would go in the tunnel. My gascolator and el. pump are located next to the nosewheel bungee.

  

 Best regards C   Karl

 



  

  From: bdavies(at)dircon.co.uk

To: europa-list(at)matronics.com

Subject: RE: Fuel return line attachment point with 912UL

Date: Thu C 23 Apr 2009 09:02:33 +0100



  .ExternalClass .EC_hmmessage P {padding-right:0px;padding-left:0px;padding-bottom:0px;padding-top:0px;} .ExternalClass BODY.EC_hmmessage {font-size:10pt;font-family:Verdana;}   Karl C

  

 Personally C I would stick to the recommended fuel supply configuration and fit two Floscan transducers as detailed in the LAA approved mod.  This ensures a constant circulation of fuel in the length of pipe that joins the two carbs together and avoids vapor locking as much as possible.  If you are prepared to accept the slightly increased risk of vapor locking C ( probably more likely in the future with the changes to Mogas) you could modify the fuel system as described by Marcel and then you only need one transducer.  My understanding is that this would require a new mod approval but I do know that a number of aircraft are flying with this arrangement having installed it under "standard aircraft practice" and they have not reported any problems.

  

 Regarding the location of the transducers C mine are in the engine compartment C well wrapped in firesleeve C and have not given any problem.  Again C if you have the option (Trigear) it is preferable to mount them outside the "hot" area. 

  

 The Floscan transducer is also used in marine applications and you can buy the identical part C at a "reduced" price C from  www.merlinequipment.com  in the UK. - Still very expensive!

  

 Note that if you are using a FS450 configured for a single transducer you will have to swap it for a double transducer model.

  

 As usual C you pays your money and takes your choice!

  

 Regards

  

 Brian

 



   From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Karl Heindl

Sent: 23 April 2009 01:25

To: europa-list(at)matronics.com

Subject: RE: Fuel return line attachment point with 912UL

 

   Brian C

 

I believe it helps a lot C but I have to think about it a little more. Are you saying that I can change my plumbing and not use a transducer in the return line ? My fuel lines are as per factory recommendations apart from gascolator and location of gascolator and fuel pump.

It would save a great deal of money; the tr. is now $ 332.- from ACS. I took advantage of the ACS discount plus the $ 175.- rebate from JPI C and payed 'only' $310 for the complete FS450

single transducer kit. 

What then is the LAA recommendation and what about Ian's mod submission to the LAA ?

 

Cheers C    Karl



 



  

  From: bdavies(at)dircon.co.uk

To: europa-list(at)matronics.com

Subject: RE: Fuel return line attachment point with 912UL

Date: Wed C 22 Apr 2009 19:12:24 +0100



  .ExternalClass .EC_hmmessage P {padding-right:0px;padding-left:0px;padding-bottom:0px;padding-top:0px;} .ExternalClass BODY.EC_hmmessage {font-size:10pt;font-family:Verdana;}   No Karl C you have not missed anything.  If you install the fuel system as recommended by the factory on a Rotax 921 C you need two transducers so that the return flow is subtracted from the total flow- leaving you with fuel consumption.  If you change the fuel supply configuration so that the return line starts before the fuel gets to the carbs C you can then have a single feed to the carbs.  The fuel flow in this single feed is the fuel consumption of the engine.

  

 Hope that helps.

  

 Brian Davies

  

   From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Karl Heindl

Sent: 22 April 2009 18:22

To: europa-list(at)matronics.com

Subject: RE: Fuel return line attachment point with 912UL

 

  Hi C

 

I am also very confused about what has been said so far. I will be installing a FS450 fuel flow gadget C and it calls for transducers in the flow and return lines. I am not interested in how much fuel is flowing to the engine C I am interested in the fuel consumption. And that consumption is the difference between flow and return. Have I missed something ?

 

BTW C I am looking for another Floscan 201 A6 with a matching K-factor.

 

Karl

 



  

[quote] From: roberthatton1(at)googlemail.com

 To: europa-list(at)matronics.com

 Subject: RE: Europa-List: Fuel return line attachment point with 912UL

 Date: Wed C 22 Apr 2009 18:00:53 +0100

 

 --> Europa-List message posted by: "Robert Hatton" <roberthatton1(at)googlemail.com>

 

 Hello Graham C 

 

 I am following this thread for I shall also be looking at fitting a fuel

 flow meter. Could I ask you to elaborate on your comment about ignoring the

 return flow for you are only measuring the fuel to the engine. I think I

 understand that with the placement of the Flowscan (from Marcel's the

 schematic) no problem in measuring the fuel going to the engine. But with

 the fuel coming back via the return line will that not eventually (after

 going through the system) go back to the engine again via the Flowscan? The

 question being C are the amounts so small not to worry about it and does this

 just build in a safety margin? Sorry to sound thick on this C I am just

 trying to get my head around what has been said so far and the schematic.

 

 

 Robert

 

 Robert Hatton

 email: roberthatton1(at)googlemail.com

 US Cell: +01 303 906 9395

 UK Mobile: +44 79 66 184171

 

 

 --

rampil

Joined: 04 May 2007
Posts: 870

Posted: Thu Apr 23, 2009 3:52 am Post subject: Re: Fuel return line attachment point with 912UL

Hi All,



I know this has been discussed before, but the present discussion

seems to discount the fact that the 912s and the 914 return fuel

quantities are quite different. The 914 has a continuous, significant

return flow while the 912s has a negligible return flow.  My

suspicion is that the flow rate in a 912s is below the range of accurate

measurement of a 201b floscan.

_________________
Ira N224XS

grahamsingleton(at)btinte
Guest

Posted: Thu Apr 23, 2009 4:56 am Post subject: Fuel return line attachment point with 912UL

rampil wrote:

 	  Quote: 	
		   



 Hi All,



 I know this has been discussed before, but the present discussion

 seems to discount the fact that the 912s and the 914 return fuel

 quantities are quite different. The 914 has a continuous, significant

 return flow while the 912s has a negligible return flow.  My

 suspicion is that the flow rate in a 912s is below the range of accurate

 measurement of a 201b floscan.



 --------

 Ira N224XS

   


	


You're probably right Ira 

Graham

sidsel.svein(at)oslo.onli
Guest

Posted: Thu Apr 23, 2009 5:12 am Post subject: Fuel return line attachment point with 912UL

For what it is worth for the discussion, which I have not followed closely:



If you use the standard Europa supplied restrictor in the fuel return line

from 912S, the return flow is an amazingly high 10 liters (approx) / a

little less than 3 USG per hour even with full fuel tank pressure head on

the return line.  

I use a Flowscan (don't have the type at hand) in only the supply line.  For

instantaneous fuel consumption reading I have a valve on the return line

that I close.  The reading then drops about 10 liters/hour after it has

stabilized (takes a few seconds due to the design of the engine driven fuel

pump).  The flow reading is accurately calibrated.  I close the valve only

at level flight at low to medium altitude to minimize the risk of vapour

lock.



Svein

LN-SKJ

-----Opprinnelig melding-----

Fra: owner-europa-list-server(at)matronics.com

[mailto:owner-europa-list-server(at)matronics.com] På vegne av rampil

Sendt: 23. april 2009 13:53

Til: europa-list(at)matronics.com

Emne: Re: Fuel return line attachment point with 912UL






Hi All,



I know this has been discussed before, but the present discussion

seems to discount the fact that the 912s and the 914 return fuel

quantities are quite different. The 914 has a continuous, significant

return flow while the 912s has a negligible return flow.  My

suspicion is that the flow rate in a 912s is below the range of accurate

measurement of a 201b floscan.



--------

Ira N224XS

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Thu Apr 23, 2009 5:33 am Post subject: Fuel return line attachment point with 912UL

Ira raises an obvious and simple solution that again a number of Europas

have- You could simply use the standard factory fuel configuration but omit

the reurn flow transducer.  The FS450 has a very simple K factor adjustment

routine that would compensate for the error caused by not measuring return

flow.  The difference between the return flow at low and high power settings

is probably negligible.  If you are worried about it you could always

measure it during the fuel flow checks required before first flight. 



This would not require a new mod (IMHO) as the fuel system would be

standard.



Brian   



--

mz(at)cariama.nl
Guest

Posted: Thu Apr 23, 2009 6:11 am Post subject: Fuel return line attachment point with 912UL

[quote:5f76066678="Barry"]Hi Marcel,



Where is your nearest airfield. If I can creep in without Mode S or an ELT I can come and show you as I am only in EDLM (near Stadtlohn).



Barry[/quote:5f76066678]



Hi Barry,



Awesome offer, I'd love to see your bird and more specifically you FF setup! My home airfield is Hoogeveen (EHHO), so that's quite close to where you are. 



I will drop you an email off-forum with my contact-details so we can make an appointment for your visit. Also gives you the opportunity to have a look at my G-BWON.



Looking forward to meeting you in person.



Marcel

Visit -  www.EuropaOwners.org

raimo.toivio(at)rwm.fi
Guest

Posted: Thu Apr 23, 2009 6:51 am Post subject: Fuel return line attachment point with 912UL

Svein,



What a nice example of creativenessity!

Who can have more that than an experimentalist?

I assume you surely have a warning system for closed returnline when the gear is down?  

I assume when not in use you close both valves in fuel turn and returnlines?

Where is your return line valve? Near main valve?



Raimo OH-XRT

---

sidsel.svein(at)oslo.onli
Guest

Posted: Thu Apr 23, 2009 7:56 am Post subject: Fuel return line attachment point with 912UL

Raimo,



<I assume you surely have a warning system for closed returnline when the

gear is down?  



My gear is always down, it's a tri-gear!   



<I assume when not in use you close both valves in fuel turn and

returnlines?



On most flights, I do not touch the fuel return close-off valve - it is left

wide open to ensure full fuel return to minimize risk of vapour lock.

During the test flying, I used it to find the best speed vs. fuel

consumption.  I then operated over farm fields that with some skill and luck

would allow a reasonably safe landing in case the engine stopped due to

vapour lock (it never coughed).  Now I use just once in a seldom while.

Nobody reading this should install such a valve without establishing where

you are with respect to the authorities.  It is a critical interference in

the fuel system - if you forget to open it again you might be in

difficulties at some stage.  When I close the valve, I keep my hand on the

valve until I have registered the reading and opened the valve again.



<Where is your return line valve? Near main valve?



Instead of the standard Europa fuel tank selector valve, I have an Andair

valve recessed in the top of the cocpit module tunnel immediately aft of the

throttle to select Main/Reserve/Off. 

I have used the Europa supplied valve in the fuel return line instead

(blocked off one valve branch) and fitted it in the standard fuel selector

valve location, on the left side of the tunnel.  I have fitted stoppers to

prevent turning the valve too far in either direction (i.e. only 90 degr

turn).



Regards,

Svein

roberthatton1(at)googlema
Guest

Posted: Thu Apr 23, 2009 10:20 am Post subject: Fuel return line attachment point with 912UL

Hello Graham,



Don't doubt your own logic! Your explanation clarifies that element of the

debate up for me! Thank you for help.



Rob 



Robert Hatton

email: roberthatton1(at)googlemail.com



--

jan_de_jong(at)casema.nl
Guest

Posted: Thu Apr 23, 2009 12:26 pm Post subject: Fuel return line attachment point with 912UL

Return flow should be roughly proportional to the square root of fuel 

pressure (differential pressure across flow restrictor).

Cheers,

Jan de Jong

kheindl(at)msn.com
Guest

Posted: Thu Apr 23, 2009 2:19 pm Post subject: Fuel return line attachment point with 912UL

  



 Brian wrote:



 	  Quote: 	
		   

 Ira raises an obvious and simple solution that again a number of Europas

 have- You could simply use the standard factory fuel configuration but omit

 the reurn flow transducer. The FS450 has a very simple K factor adjustment

 routine that would compensate for the error caused by not measuring return

 flow. The difference between the return flow at low and high power settings

 is probably negligible. If you are worried about it you could always

 measure it during the fuel flow checks required before first flight. 

 

Okay C I think I will do just that. I will modify the wiring harness to allow for a second transducer C but install another tr. ONLY if it turns out I need one. Saves a lot of money and hassle and should be completely safe. 
	


  

 Karl

 

 

 	  Quote: 	
		   --> Europa-List message posted by: "rampil" <ira.rampil(at)gmail.com>

 

 Hi All C

 

 I know this has been discussed before C but the present discussion seems to

 discount the fact that the 912s and the 914 return fuel quantities are quite

 different. The 914 has a continuous C significant return flow while the 912s

 has a negligible return flow. My suspicion is that the flow rate in a 912s

 is below the range of accurate measurement of a 201b floscan.

 

 --------

 Ira N224XS

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=240878#240878

 

 

 

 

 

 

 

 

 

 

 

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 06:30:00

 

&=======================
	


&g============

 	  Quote: 	
		   

 

 


	


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