Jim,
You and Ed Anderson have made some very good points. When I initially wired the plane, I
didn’t see the need to add another switch, but now it looks like I’ll be adding
a switch. I just have to figure
out where to put it. I’m changing my transfer pump to a timer, so I may just
re-use the switch for it, and locate a push button and LED elsewhere for fuel
transfer. Maybe near the fuel
gauge, if I can find a spot.
Thanks for the advise,
Steve Brooks
-----Original
Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]On Behalf
Of Jim Sower
Sent: Wednesday, March 17, 2004
2:34 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: mainfold
hose
<... I don't see allot of them burning along the highways ...>
Actually, I DO see some burning. Not every
day, but enough to notice. IIRC nearly ALL airplanes have an emergency
fuel shutoff. Even if they ALL didn't, I
certainly would. That said, to have the Master the only way to shut off
fuel in an emergency defeats
practically all of the other
procedures you might want to avail yourself of in the event of a fire - like
navigating, communicating your problem to someone else (like ATC), doing anything useful at all if the problem
occurs at night, etc . To be honest, I cannot think of a single reason of
any consequence that would lead me to wire fuel pump(s) exclusively through the
Master switch. I see no plus side at all, and giving away so much
flexibility and so many alternatives for no significant gain is IMO profoundly
ill advised. I'll have more than enough unanticipated problems without
deliberately painting myself into a corner in the design stage. Design is
where I give myself all the flexibility I can.
Personally, I would want
the capacity to alternate fuel pumps from day to day or flight to flight.
I would bias usage toward one just to keep wear uneven, but I don't like the
idea of keeping one idle nearly all the time, and they draw enough current that
I regard it as foolish to keep them both running all the time. My
inclination at this juncture is to use distinctive (and/or possibly guarded)
switches for the fuel pumps and use one pump roughly twice as much as the
other.
What compelling reason do you have for
wiring it through the Master? What does it buy you that you couldn't
achieve better otherwise
What, precisely, IS your procedure for
engine fire??.... Jim S.
Steve Brooks wrote:
Jim,
Would you please elaborate about why you feel that
the primary pump controlled only by the master switch is a very serious fire
hazard ?
Cars don't have a separate off switch for the fuel
pump, and I don't see allot of them burning along the highways.I would really
like to know what the risks are.
Steve Brooks
-----Original
Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Jim Sower
Sent: Wednesday, March 17, 2004 11:40 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: mainfold hose
<...
my primary pump runs as long as the master switch is on ...>
I would regard that as potentially a very serious fire hazard.
<... was
concerned about a main pump switch that could be accidentally turned off in
flight ...>
I would be inclined to look at that concern as exaggerated if not totally
bogus. A switch on the panel cannot be turned off completely accidentally - you are deliberately turning something off, and if you hit the wrong
switch, the engine will die so fast that you will still have your hand on the
switch and can turn it back on immediately. Additionally, how often are
you manipulating panel switches at altitudes where a 1-second inadvertent
shutdown would pose a problem? If you are really REALLY afraid of
inadvertent shutdown, how about using guarded switches on the hp pumps?
I would NOT
hard wire a pump through the master switch ... Jim S.