flyrotary@lancaironline.net Mailing List Archive

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.

Steve Brooks wrote:

Paul,
I don't think that it matters which port you use. Either one should give it
the manifold pressure input. You definitely want to block the other one, or
if you're going to use a manifold pressure gauge, that would be a good point
to connect it.

I was interested in the switch idea on the fuel pump. I have my auxiliary
pump on a switch, but my primary pump runs as long as the master switch is
on. I was concerned about having a switch on the main pump that could be
accidentally turned off in flight. I have noticed on occasion though,
during my test runs that there was some fuel in the intake plenum that
accumulated a while after shut down. I assume that this is due to some
leakage by the injectors caused by still having fuel pressure on the fuel
rail.

I am interested to see what other responses you get on the fuel pump switch.
I may want to consider putting one on, though it would have to be located
where it wouldn't get shut off accidentally.

Steve Brooks
Cozy MKIV 13BT
CH 25 - about ready to shoot the primer

-----Original Message-----
From:   Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of sqpilot@earthlink
Sent:   Wednesday, March 17, 2004 12:14 AM
To:     Rotary motors in aircraft
Subject:        [FlyRotary] mainfold hose

I have to ask another question. My MicroTech ECU has a male fitting onto
which I connected the supplied rubber hose to the TWM throttlebody. The TWM
throttlebody, however has two male fittings to which the hose could be
connected. They are both in the same area, so it shouldn't matter which one
I connect to. The question is.....Should I plug the one that I am not
using? Right now I just connected a 1 inch long hose to it and stuck a bolt
into the end of the hose to plug it, not knowing if I should have plugged it
or not.
     One more question, please. I just finished hooking up two toggle
switches to allow me to turn the high pressure fuel pumps on and off.
Recently, there have been a few posts recommending turning the fuel pump off
prior to engine shutdown to eliminate those few drops of fuel in the
throttlebody. Do you just turn the pumps off for a few seconds and then
turn off the ignition, or just turn off the pumps and let the engine die
from fuel exhaustion, similar to pulling the mixture lever to shut down a
Lycoming?   Inquiring mind wants to know. Thanks in advance for all replies
and advice, as ususal.   Paul Conner, 13b powered SQ2000, engine running.

>> Homepage: http://www.flyrotary.com/
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--
Jim Sower ... Destiny's Plaything
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T