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@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Karl Heindl
Sent: 23 April 2009 01:25
Subject: RE: Europa-List: 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@dircon.co.uk
Subject: RE: Europa-List: Fuel return line attachment point with 912UL
Date: Wed, 22 Apr 2009 19:12:24 +0100
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@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Karl Heindl
Sent: 22 April 2009 18:22
Subject: RE: Europa-List: 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
> From: roberthatton1@googlemail.com
> To: europa-list@matronics.com
> Subject: RE: Europa-List: Fuel return line attachment point with 912UL
> Date: Wed, 22 Apr 2009 18:00:53 +0100
>
<roberthatton1@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@googlemail.com
> US Cell: +01 303 906 9395
> UK Mobile: +44 79 66 184171
>
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Graham
> Singleton
> Sent: Wednesday, April 22, 2009 1:12 PM
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Fuel return line attachment point with 912UL
>
> <grahamsingleton@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======
>
>
>
href="http://www.matronics.com/Navigator?Europa-List";>http://www.matronhref
"http://forums.matronics.com";>http://forums.matronics.com
href="http://www.matronics.com/contribution";>http://www.matronics.com/c
. Checked by AVG - www.avg.com
>http://www.matronics.com/Navigator?Europa-List
ronics.com
ww.matronics.com/contribution
17:25:00
|