Raimo Toivio wrote:
> 2) Fuel systems
> - routing outside the cabin (weight penalty none or some)
> - return line with one-way-valve or emergency off-selector (weight penalty few
hundred grams)
> - do not use original glass fuel filters (weight penalty none or even less)
> - consider the safety of sight gauge and its location (weight penalty none)
> ( I have it but between the seats and it is calibrated only to use when on the
ground and taxi-position)
> - have a fuel warning /gauge/pressure gauge /computer (weight penalty 100grams
to 1 kg)
I have the whole fuel system in a separate sealed box, with lexan top
that can be opened. The two fuel pumps, the two fuel filters, the two
one way valves, and the fuel flow sensor. Lots of connections, and lots
of opportunity to leak. There is one hose in, and one hose out, and
almost all potential leak sources are inside. There is more to it: there
is also a small access door on the underside of the fuselage, allowing
easy access to the master Andair fuel filter. Now, if there is a leak,
it will drain through this access door, which is intentionally not
sealed. The whole point is that if there is a fuel leak, I don't want to
have the fuel in the "foot bath" in front of my seat, especially not
when I'm about to make an emergency landing because of the fuel leak!
A side benefit is that the fuel vapors also choose the easy way out,
that is, to the outside of the airplane. I have not the fuel smell
inside the airplane so many people complain about. If I mess with the
filters and spill some fuel, it will just fall out of the airplane, and
never make it into the fuselage. Weight penalty? Depends on the
construction, shouldn't be more than 500 gram.
> 3) Doors
> - use unintentioned opening guards and secure them with pip-pins to levers
> (weight
penalty 100 grams)
I have to work on this.
> 4) Cowlings
> - do not make those little oil/water check doors - so you have to take whole
upper cowling away and see and check same time much much more (weight penalty
none, use cam locks or equal - so it is pleasure to open so often you like - I
do it every 5 flight hrs)
This is radical, but a good point actually. Although it may invite you
to not bother with checking the water and oil if you are in a hurry to
go home. I know, you should never fall into this trap, but we are all
human and it is temptive to skip checks that take too long if bad
weather is approaching and you need to leave the airport.
> 5) Electrics
> - use two serial connected master switches; so called panel mstr leaves juice
for trim, stall warner, charging for emergency batteries, clocks, burglar
alarms,
horns, convenience lights AND an engine starter - total master cuts everything
(weight penalty none, normally my total master is always on, I close it
only during longs stays over two weeks or just before possible crash I wish,
panel
mstr switch uses light weight 40A relay which uses only few milliamperes,
total mstr switch is mechanical with "a key" and uses 0 amperes)
Good alternative. Although a second master switch increases the amount
of failure points. I have one master switch (well, two actually, but I
have two separate electrical systems), and once that is off, the whole
plane is without power. I have further a multi pole plug on the fuselage
for "ground power", and this feeds a relay that energizes the connection
to the outside world. This way I can charge batteries, power burglar
alarms, etc. Once this plug is off, the relay falls off and it can not
be powered during flight at all.
Frans
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