Today's Message Index:
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1. 12:40 PM - Re: Fuel System Manager (wsimpso1)
2. 03:08 PM - Re: Fuel System Manager (wsimpso1)
3. 08:03 PM - Re: Fuel System Manager (911pete)
Message 1
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| Subject: | Re: Fuel System Manager |
As the holder of an MSE(IOE) - Yeah some folks would call it imaginary engineering
- I feel compelled to point out that all control labeling should talk to what
function is being achieved. You do not want the pilot to need expert knowledge
in switchology and wiring and failure modes. You want the pilot to look at
the switches and know function they will get by moving the switch.
In this case, I suspect you want to tell the pilot that this is FUEL TRANSFER,
then the left side function is on the left side and labeled LEFT, the right side...
Then between the switches, I would have OFF meaning no flow from that tank, AUTO
meaning it manages flow Automatically, and MANUAL meaning you turn it on and
off yourself. Probably park the flow to OFF with the switch down...
Then below the switches, you might have a warning about what happens when electricity
is lost to these solenoids like "Power Loss Defaults to OFF" or similar.
That takes us back to failure mode management. If the fuse or circuit breaker for
one of these solenoids fails, which position do you want the valve in then?
Perhaps you want a solenoid that only requires power to change state so it stays
where it is when electricity becomes unavailable to the solenoid. Think hard
about a system that defaults to free flow - it will do that when you are shut
off too and just pour fuel on the ramp...
There are many ways to have redundant power for your solenoids. The easiest is
just to have two independent power buses and run one solenoid of one and the other
off the other. That may be good enough for you, or you might go further
- have a three-position switch to select which bus is powering the solenoids or
even two switches to determine which bus is powering which solenoid.
I have two transfer pumps each available to one bus on one switch and each available
to the other bus on the other switch. This allows me to power either pump
from either bus or even both pumps simultaneously from either bus. It also prevents
attempting to cross power a whole bus through one fuse and switch.
Seriously, you do not want any one thing that breaks to turn your bird into a high
speed glider.
Billski
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http://forums.matronics.com/viewtopic.php?p=516919#516919
Message 2
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| Subject: | Re: Fuel System Manager |
On my last post I described my system in error - I have a DPDT switch for each
pump (the OP would have one switch for each solenoid) with positions for OFF -
Main Bus - Aux Bus. So each pump could be powered by either bus, and we can not
mistakenly try to power a whole bus through one switch.
Where we might want to power both buses from one design, we engage the Bus-Tie
- Bob calls it the cross-feed in Z-14.
Billski
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http://forums.matronics.com/viewtopic.php?p=516920#516920
Message 3
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| Subject: | Re: Fuel System Manager |
Here is picture of another Viperjet panel that shows what I posted earlier
I have flown many planes in the AF as well as the airlines. Warnings below a switch
is something I don't think I've ever seen. This type of information is
normally in the aircraft manual.
In previous posts I explained what happens in the event of loss of electrical power.
There is no way for the fuel to overflow on the ramp if the engine is shutdown
as the jet pump, the heart of the fuel transfer system, needs high pressure
fuel from the running engine to move any fuel from the wings to the main
tank.
Pete
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516921#516921
Attachments:
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