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Date: Mon, 30 May 2005 21:11:53 -0500
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Fuel Tank Selection
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Exactly

Echo Lake Fishing Resort (Georges Boucher) wrote:

> If there is one chance in a million that "BOTH" will cause fuel 
> starvation, why use it. Use a low pressure transfer pump between tanks 
> if you want redundancy use 2.
> Georges B.
>  
> /-------Original Message-------/
>  
> /*From:*/ Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
> /*Date:*/ 05/29/05 23:08:55
> /*To:*/ Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
> /*Subject:*/ [FlyRotary] Re: Fuel Tank Selection
>  
>
>
> Perry Mick wrote:
> Dale:
>
> With a BOTH function and such a low gravity head, the tanks may not 
> feed equally, or worse, the engine quits while there is still fuel in 
> one of the tanks, the same problem that Jim S. has described having 
> with his Velocity sump.
> If you have an EFI pump in each tank and both pumps are providing fuel 
> to the EFI fuel rail at the same time, that would not be the same 
> situation, there is no gravity feed from separate tanks to a common 
> point in that design.  But if you lose a pump, you lose the fuel in 
> that tank too.  That could get dicey when you get real low fuel in one 
> tank, switch  on the other pump and that's when you find out it's failed.
>
> I'm doubtful that this BOTH function was the cause of Paul's accident, 
> agreed but I still think you want to avoid a BOTH function in a LEZ or 
> other low-wing fuel system.  But it can get dicey if you have to use 
> ALL the fuel in one tank or the other.
>
> Perry
>
> Bill,
>
>   Thank you for that clarification. When I read Perry's
> comments, I was wondering "why?" - because the system I'm
> building has the functions: Left, Right, Both, None.
>
>   Now I'm not so worried, because each high pressure fuel
> pump draws from it's own tank and the only point of inter-
> connection is where the lines join at the fuel rail(s).
>
>   I borrowed the basis of my setup from Marc and Nadine
> Parmalee's COZY:
>
> http://www.marcnadine.com/fuelvalve.html
>
> Dale R.
>
> > From: "BillDube@killacycle.com" <billdube@killacycle.com>
> > Date: 2005/05/29 Sun AM 02:03:31 EDT
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Subject: [FlyRotary] Re: Paul's Fuel System Error
> >
> > About a year ago I did a little "Google" research on the John
> > Denver fatal crash. The bottom line appeared to be that one tank was 
> empty,
> > and the fuel selector was not fully turned to the other tank. (It 
> was in a
> > very awkward position to reach, and this may have also caused the 
> pilot to
> > auger in while attempting to reach it.) Thus, it was in the 
> equivalent of a
> > "both" position. This caused air to be drawn in to the fuel supply line
> > from the dry tank. This, in turn, caused the pump to lose its prime and
> > stop pumping fuel to the engine.
> >
> > As Perry mentions in his post, only a gravity feed fuel system can
> > have a "both" type fuel selector. Low-wing aircraft that have negative
> > pressure in the fuel lines from the tanks must NOT have a "both" 
> position
> > on the fuel selector, otherwise the pump (or the sump) will suck air 
> if one
> > tank runs dry (or if there is a leak in a fuel line.)
> >
> > This kind of makes you want to put a pump in each tank.
> >
> >
>
>  Homepage:  http://www.flyrotary.com/
>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>
>
>  
>
> 	
> 	
>
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