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Re: REFLECTOR: Fuel system safety
Martin, you may not be able to envision this valve but as I have written before,
NO POWER REQUIRED TO HOLD POSITION, 250 Millisecond STATE TRANSFER TIME (probably
fast enough for most emergencies), and I do have a backup battery so that
eliminates the theory that I might loose power. Mechanical valves fail also as
can be shown by a number of cable operated fuel transfer valves that have stuck.
Price for the valve is less than $60 and it is a lot easier to install and locate
the transfer switch. Probably only a few million of them used each day in trucks,
busses, and motor homes.
> For the life of me I cannot envision an electrically operated valve that could
> be safely installed to fit the objectives of its use. In a fail-safe mode,
> that being no electrical current needed to keep the valve open, power would
> have to be applied to close it. In our off field landing we want to cut our
> battery power off as soon as possible, opening up our valve. I thought the
> criteria was to be able to close the valve off in such cases.
> Next, If power is required to keep the valve open, in the event of an
> electrical failure, whether it be the primary source, a switch, the solenoid
> on the valve, a broken wire, whatever, the valve closes in flight. I happen to
> know first hand that an aircraft can fly just fine with the battery master
> switch off, at least in a conventional aircraft. But not if the fuel cutoff
> valve is closed.
> In either scenario, with the electrically controlled valve there is a risk
> factor and safety design criteria that is not meet. My opinion is that if you
> opt for a valve at all, make it mechanical so you can control it at your
> desecration. But as pointed out in earlier postings, if you don't "exercise"
> this valve regularly, the time you need to move it you might find it to be
> stuck in position!
// James F. Agnew
// Tampa, FL
// Velocity 173 FG Elite ( http://www.VelocityAircraft.com/ ) under construction