Will,
You could achieve the objective of shedding all non-essential loads by
turning off the master and having an =9Cemergency bus=9D for
essential items. This does not need to be elaborate =93 it could
simply be a 3-way changeover switch for your second pump: BUS-OFF-BAT
instead of the usual BUS-OFF.
In your case, with a mechanical pump that would normally keep the engine
going unless you happen to be on full boost at the time of alternator
failure, this would allow you to shed everything then switch the pump to
BAT if you need it.
Good luck with your trip!
Best wishes,
Mike
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of William
Daniell
Sent: 06 April 2018 15:11
Subject: Re: Europa-List: Rotax 914 Electric fuel pumps
Mike
Naturally I would never leave the pumps on after parking because I
always use and follow my checklists :-). Actually mine are quite noisy
Bosch injection pumps so its probably not likely.
Thanks for your comments, much appreciated and valid points.
My main aim is to simplify the electrical system precisely for safety
sake. I have a secondary aim which is my flight to the US. There are
some quite long legs over water or jungle (which amounts to the same
thing). I want to be able to maximize the electrical range by switching
off all unnecessary electrical loads. For me this includes everything
except what is needed to run the engine range as my back up batteries
and handheld devices will take care of the flying aspect.
So ideally Id like to have one buss which I can switch off to achieve
this minimal electrical load. At the moment I think the only things
which require separate switches are
* Master
* mags
* Avionics 1 - ADSB XPNDR RADIO Intercom
* Avionics 2 - AP servos in case they start acting strangely I would
like to able to switch them off separately.
* Fuel Pumps x 2 - sometimes on the ground one wants to fiddle with the
EFIS without the pump draining the battery.
* Landing and Anti Col lights
Connecting a pump to the battery might be a moot point because sudden
and complete alternators failures are very rare and also my Rotax 912
turbo has a mechanical pump which in theory should maintain up to 29 in
at sea level. I have yet to test this.
Will
William Daniell
LONGPORT
+57 310 295 0744
On Thu, Apr 5, 2018 at 7:32 PM, Mike Gregory <m.j.gregory@talk21.com>
wrote:
Hello Will,
You could connect the second fuel pump direct to the battery, via a
fuse/CB and switch as for the trim circuit, but why would you wish to?
In the event of alternator failure, unless you have a low-capacity main
battery, you have plenty of time to shed loads according to how long you
need to keep airborne. In the event of a forced landing and turning off
the main bus with the master switch, the electric trim is kept
operational to avoid heavy stick forces, but this logic does not apply
to the fuel pump.
If the engine has stopped and you are making a forced landing, a single
action to turn off the master switch before contact with the ground will
kill all electrics (except the trim and your built-in standby batteries)
and minimise the risk of a post-impact fire caused by an electrical
short circuit and hefty current from the main battery. In particular,
it will also stop the fuel pumps from potentially squirting fuel all
over the wreckage, without your having to remember to switch off your
fuel pump off separately.
Of course, you would never shut down the engine after parking, turn off
the master switch and forget to turn off your fuel pump!
Best wishes,
Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of William
Daniell
Sent: 05 April 2018 17:25
Subject: Europa-List: Rotax 914 Electric fuel pumps
I have the Europa System with one of the pumps connected direct to the
alternator and the other to the bus.
I get the logic of a direct connection to the alternator.
Why isn't the other pump connected direct to the battery so that if the
alternator fails you can switch off the buss run one pump off the
battery?
(My EFIS has a back up battery and I carry a hand held so I can operate
with the buss off.)
thanks
Will
William Daniell
LONGPORT
+57 310 295 0744
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