Just a quicky: 100LL is avgas here (in Europe too i guess)
second quicky: If i read the story correctly is this not about Vito or
whatever other material, but about a certain batch of fuelpumps with
defects.
Jos Okhuijsen
Tony Renshaw <tonyrenshaw@optusnet.com.au> kirjoitti Mon, 26 Jul 2004
> <tonyrenshaw@optusnet.com.au>
>
> Gidday,
> I have to say that I am getting tired of dealing with the capabilities of
> various seals for both my fuel and brake systems. Whoever comes up with
> an
> inert, stable seal material for all applications will make millions very
> happy, few quite unhappy, and themselves very rich. I specifically am
> challenged with Viton for fuel systems vs Buna or other materials. I
> have a
> recently purchased a SUCO fuel pressure switch, which is actually an oil
> pressure switch. It was sold to me with the assistant highlighting it has
> an internal Viton seal. Well, I took a gamble and bought it, but
> subsequent
> to that I have stumbled on something I have read once before on the web
> from a Long Eze pilot back in 1988 who had an engine failure directly
> attributed to the collapse of a viton component within a Facet pump. For
> interest I have pasted the accident summation below.So, I now have
> potentially a $85.00 component.
> Even in the example below, when the author admits he is using 100LL,
> which
> to my knowledge is not avgas, then quotes the seals in his pumps, Viton,
> as
> being not stable in Avgas, nor Buna N seals. So, unless I got it wrong he
> states he is using one type of fuel and then states another will cause
> the
> problem. I can only presume I have this wrong, as why else would an
> author
> write such as speel. If however he did get it wrong, or in fact I did, it
> highlights the confusing nature of these issues. They all change again
> when
> you start talking brake fluids, and they vary amongst them too depending
> on
> whether you are talking silicone or synthetic, or petroleum based. So, if
> anyone can reassure me that my switch won't rot away to nothing and will
> actually do its job in mogas, but not avgas, well it is this type of
> definitive statement I want. Or, of course, if there is another path to
> clear up this mist, well I'd appreciate it.
>
>
> LONG-EZ. DEFIANT, ELECTRIC BOOST FUEL PUMP ALERT
> From CP57, Page 11 (October, 1988)
>
> Returning to his home base airport after a flight, a Southern
> California Long-EZ pilot was approaching the 45 degree entry to downwind
> when, abruptly, his engine quit. He was unsuccessful in getting it
> restarted but, to his credit, he flew the airplane, announced his
> situation
> and made an uneventful, successful landing. Feeling a little weak around
> the knees, he pushed his airplane into his hangar and went home.
> The next day, he conducted a careful examination of the aircraft
> and
> discovered that the Facet solid-state fuel pump was completely blocked
> and
> would not allow any fuel to pass through to the engine driven mechanical
> pump! One of the two valves in the pump had deteriorated in the 100LL
> fuel
> and had worked its way out of the metal cage that normally prevents this,
> and had been sucked into a position that prevented the flow of fuel. The
> part number on the mounting flange of this pump was 480615. The plunger
> valve was made of VITON- this pump is no longer being manufactured.
> Before next flight, check the part number of your pump. If you have
> one of the following part numbers 40023, 480615, 480616, remove the pump
> and replace it.
> The most desirable Facet solid-state pumps that we recommend are
> part
> #40108 for 12 volts and part # 40154 or 480610 for 24 volts. Both pump
> fuel
> at a regulated maximum 6 psi, and the valves in these pumps are pure
> nyIon
> which, other than swelling very slightly in avgas, are not affected nor
> do
> they deteriorate. The design of these valves (the foot valve and the
> plunger valve) are such that they cannot physically get into a position
> where they can prevent fuel from flowing through the boost pump. Both of
> the above pumps have AN-style, 370 flare fittings which fit 3/8" tube, AN
> 818-6. Nuts.
> Facet manufactures over one hundred variations of the small square
> solid-state fuel pumps. The above two pumps have AN-type flare fittings
> machined right on the pump bodies and we prefer this type because they
> are
> easy to install (no elbows or nipples required), but also because these
> two
> models have only nylon valves, no rubber, Buna, or Viton. Many of FACET's
> other models have Viton plunger valves or Buna N check valves and these
> will deteriorate in avgas. These are specifically for use in some other
> liquid known not to affect these materials.
> To check your pump, remove it and look into the inlet and the
> outlet
> using a small flashlight and verify that the inlet valve (foot valve) is
> a
> round, white dome or ball (nylon), not a flat, black rubber disc. Verify
> that in the outlet there is a white nylon valve under a steel pin which
> crosses the port and retains this valve. If this valve is dark gray or
> black (Viton), remove the pump before next flight and discard it. If you
> have to a pump with female pipe threads (to accept elbows or nipples) due
> to your firewall layout, choose one with 3/8 NPT female threads rather
> than
> the 1/8NPT female threads, but examine it closely to be sure it has while
> nylon valves in the inlet and the outlet ports. Discard it if there is
> any
> black or gray Viton, Buna N or rubber valves.
> If you have had your Facet fuel pump more than a year or so, you
> probably have one that could go bad. AT a cost of approximately $30.00,
> it
> is not worth the risk. Remove it, discard it and install a new one as
> called out. We believe that the serious consequences that could result
> from
> a fuel supply stoppage, more than justifies the immediate replacement of
> any suspect pump.
> We have replaced the boost pumps on Burt's Defiant and on Mike and
> Sally's Long-EZ and we recommend in the strongest possible terms that you
> do the same.
>
> Reg
> Tony Renshaw
> Sydney Australia
>
> Classic 236 B.B. Taildragger
> Tail, Wings, Ailerons, Flaps Complete and Connected
> Lower Fuse in Jig, Tail Torque Tube installed
> Mass Balance assembly installed and deflections sorted
> Roof Panel between doors completed.
> Photos at:
> http://forum.okhuijsen.org/modules.php?set_albumName=TonyR&op=modload&name=gallery&file=index&include=view_album.php&PHPSESSID=902b69917a45f8b18ac84fe3f85a704b
> Intended Engine: 912S CS prop (model undecided)
> Instrumentation: Undecided
>
>
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