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quantity. So, if you load the same
amount of fuel, your machine will
weigh more with Jet A, but if you fill
the tanks, you will use fewer litres
and less money.
JP4 is like Jet B but with a corrosion
inhibitor and anti-icing additives. It
was the main military fuel but is
being superseded by JP8, at least in
the USA. JP5 has a higher flashpoint
than JP4, and was designed for US
navy ships (similar to Jet A). JP8 is
like Jet A1, but has a full set of
additives (or e-numbers, if you like).
Aircraft parked overnight should
ideally have tanks completely filled
to stop condensation, but this is
impractical if you expect a full load
the next morning and don't have
room for full fuel as well, in which
case be prepared to do extensive
sampling from the tanks. Half filled
drums left overnight should not be
used for the same reasons, but, in
remote places (like the Arctic), fuel is
a precious commodity and you think
more than twice before discarding
any (as it happens, drums are scarce
too, and they may get used for all
sorts of things, particularly diesel for
drills, so beware – always smell the
contents first). Full drums are usually
delivered to a remote cache by Twin
Otter or something, and they should
be sealed straight from the
96 The Helicopter Pilot’s Handbook
refuellers—as you tend to use any
remainder in a very short time, this
can be minimised somewhat. Look
for a fill date, as fuel over two years
old should be looked at sceptically.
Also look for a large X, which is the
accepted symbol for contamination,
although not everyone has a black
marker with them.
An unofficial, but excellent (if not
better) substitute for water paste or
detectors with jet fuel is food
colouring, which you can at least get
in the local grocery store, even if
you're in Baffin Island. All you need
is one drop – if there is no water
present, it will stay as a few lumps. If
there is water, the colouring will go
directly to the water droplets, and
assume their shape, which are more
visible anyway, from the colour.
Drums
Drums should not be stored
vertically for long periods, because
the bungs are not airtight, even
though they might stop fuel from
leaking out (although it is good idea
to stand them vertically for about
half an hour before you use the fuel).
When the contents contract as the
air cools overnight, water inside the
rim and collecting around the bung
can be sucked in as well, so either
store the drums on their sides, with
openings at 3 or 9 o’clock, or stick
something underneath at 12 o’clock
that causes the drum to slant enough
to stop rainwater collecting and
covering the bungs. Other openings
or connections should be protected
with blanks or covers, or at least
have their openings left facing
downwards. Drain plugs, valves,
filter bowls, sumps and filter meshes
should be checked daily for
sediment, slime or corrosion. Always
have spare filters.
The reason why long-term storage is
not good for fuel (up to two years
for drums is the accepted maximum,
but some companies reduce this to 1
year) is partly because of daily
temperature changes. When it is
warm, the fuel expands and some of
the vapour-air mixture is driven out.
When it gets cold again, the fuel
contracts and fresh air is sucked in,
to mix with more vapour. As the
cycle repeats itself, the fuel inside
gradually loses its effectiveness (it
loses burn-units). Humidity will
mean that water vapour will get in,
too, and condense into liquid.
Oxygen will also cause a gum to
form, which is more apparent when
fuel evaporates (the fuel filter is
designed to remove it). Keeping the
container full will minimise this,
which also applies to fuel tanks on
machines parked overnight. 100/130
will apparently last for decades,
actually longer than the drum, which
will deteriorate first, due to the
chemicals inside - fuel in drums will
interact with the Teflon coating on
the inside, if it has fallen off.
Containers should be filled to 95%,
and sealed tightly, in a place where
the temperature is mostly below
80°F, out of direct sunlight. The 5%
airspace allows room for expansion.
Operational Stuff 97
Fuel Checking
Each day before flying, and when
the fuel is settled, carry out a water
check in aircraft and containers (but
see below, for drums). Collect
　
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本文鏈接地址：The Helicopter Pilot’s Handbook(64)