You need also to review the report at
http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafe
ty_507739.hcsp
Duncan McF.
----- Original Message -----
From: "Carl & Dot" <carl_p@ntlworld.com>
Subject: Re: Europa-List: Benwick FM 1053 Fuel Flow Computer
>
> I have to disagree with those that say the Benwick system is a bad one.
Many
> people (including myself) have used them without problems. I am aware that
> the restrictor is a potential hazard if it were to become blocked by a
lump
> of dirt but there shouldnt be lumps that size floating around any fuel
> system. Fitting a small (sintered brass) filter just before the sensor
will
> eliminate any risk of such a blockage occurring.
>
> The size of the restrictor may look small but I seem to recall that it is
> larger than the shank end of a 1/16 in drill. If you have lumps of muck
this
> size in your fuel then you are bound to have problems sooner or later
> whether you have a flowmeter in the line or not.
>
> For the record our original fuel flow tests (with the sender in situ )
> exceeded the maximum flow required by over 100%. On the rotax 912, 25
> litres per hour (maximum flow) equates to 416 millilitres per minute. From
> memory our fuel system was delivering in excess of 1200 millilitres per
> minute (72 litres per hour). This was with both pumps working (ie:
> electrical and mechanical),
> and shutting down the electrical pump made very little difference to the
> readings. We have a fuel pressure sensor on the carb side of the flowmeter
> and never experience low pressure readings (ie: below 4psi).
>
> The main filter in our system is incorporated in the gascolator - not an
> Andair, but a flat steel gauze incorporated in the top of the gascolator
> housing. As an
> additional precaution, ALL fuel that we use is filtered through a gauze
mesh
> filter funnel (the type with the water trap) . Relying on the aircrafts
> filters to keep the dirt out is IMHO taking an unnecessary risk.
>
> If you are experiencing a drop in pressure in your fuel system I would
look
> elsewhere for the cause of the problem, possibly a clogged main fuel
filter.
> If the installation is new it is a real possibility due to the crud in the
> tank.
>
> The Benwick fuel flow sensor itself can be purchased from RS components.
>
> Go to www.rsww.com and the part number is 256-225 (described as a
> Liquid Flow Sensor Dual Range). Unfortunately the price has rocketed since
I
> last looked to 78 plus VAT. Used to be about 30 !!!
>
> If you are simply looking to replace an existing sender, then I dont see
the
> point of replacing the whole system. If you are shopping around for a new
> system than maybe the flowscan is a better bet (as long as you can get it
> shipped to the UK without additional costs and taxes (ie: VAT).
>
> If you have purchased a Benwick, dont throw it away. Properly installed
> there is nothing wrong with it.
>
> Hope this helps,
>
> Carl P
> G-LABS
>
> ----- Original Message -----
> From: "nigel charles" <nigelcharles@tiscali.co.uk>
> To: <europa-list@matronics.com>
> Subject: Re: Europa-List: Benwick FM 1053 Fuel Flow Computer
>
>
> <nigelcharles@tiscali.co.uk>
> >
> > Hi William
> >
> > >I was unaware of this knowledge about Benwick, but I must say I have
> never
> > seen a drop in fuel pressure (sample point down stream of Benwick) at
full
> > throttle (mine's the 912). <
> >
> > You probably won't. However if you do the fuel flow check you are
bleeding
> > off an extra 25% above your max fuel flow. The restriction will then
cause
> > the pressure to drop just below the minimum (about 2.25psi if my memory
> > serves me correctly). Practically speaking your setup is OK provided you
> get
> > no contamination in the sender causing fuel starvation. This has
happened
> at
> > least once
> > with the Benwick sender and I believe the PFA got close to banning fuel
> flow
> > senders. I am still surprised they allow use of the Benwick
> > sender.
> >
> > >> Where can I buy a Flowscan sensor and are they
> > directly interchangeable, or do I have to throw the Benwick unit away?<
> >
> > I bought mine direct from Floscan in Seattle (about $160 but money well
> > spent). I haven't got their contact details to hand. Try Google. If no
joy
> > remind me in a couple of days time and I will look it up for you. The
> > Floscan is cast alloy and comes with 1/4" female NPT threads. Either
> > incorporate it into a rigid pipe system or buy a couple of adaptors to
> mate
> > with the 5/16" rubber hose.
> >
> > Regards
> >
> > Nigel
> >
> >
>
>
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