曝光台 注意防骗
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takes more energy, so melt it first.
Preserve your machine’s heat as
much as possible on the ground, by
covering vital areas as soon as
possible after landing, not opening
and closing doors too much, etc. It’s
very important that it does not get so
364 Canadian Professional Pilot Studies
cold that it won’t start again, so you
might consider starting up every
couple of hours or so, which will
both use fuel and battery capacity –
certainly, in the average car, it takes
about half an hour’s driving to
replace the energy taken by one start,
and I’m sure it’s worse with a
helicopter – a depleted battery will
sooner or later result in an expensive
hot start. At the very least, remove
the battery and keep it warm. If you
see fan heaters around the helipad,
they are for putting under the covers
to keep the engine and gearbox
warm (all night). Light bulbs are
good, too, around the FCU.
Special attention should also be paid
to the following:
· That correct oil and grease is
used and special equipment (like
winter cooling restrictors) is
fitted to keep engines warm.
For Bell 206s, at least, below –
40C, your oil must meet MIL
L7808 specifications, and you
will need fuel additives in all
fuels other than JP4 below –
18C. Note: It has been found
that when visible water is
present in jet fuel containing
anti-icing additive, the additive
will separate from the fuel and
be attracted to the water. After a
certain amount, thought to be
about 15%,the density of the
new liquid changes so much
that it is not identified as water,
and will therefore pass through
water filters, and will also not be
detected by water finding paste,
which is not, in any case,
intended to detect water in
suspension. Where the ratio
becomes 50%, as much as 10%
of whatever is going through
the filter could be water, which
is very likely to get to the
engine, since the filters on the
airframe itself are not as
restrictive.
· Use deicing fluid if possible—
scrapers do not leave pretty
results. Fluid, if it's thick
enough, helps prevent further
ice forming (see the tables in
Chapter 6). Don't forget to fit
engine blanks, etc. before using
them. Deicing fluids are also
good degreasers.
· That windscreens are defrosted
(keep moving a mechanical
heater around, or it might melt
the perspex). Don't forget to
have a cloth handy for wiping
the windscreen from the inside
when it mists up.
· You have proper tie-downs and
pitot/engine covers, static vent
plugs, etc.
· That heating systems are
working properly and don't
allow exhaust into the cabin (if
you get regular headaches,
check for carbon monoxide
poisoning).
· De-icing and anti-icing
equipment is working properly
and that all breather pipes, etc.
are clear of anything that could
freeze.
· That the aircraft has not been
cold soaked below minimum
operating temperatures. If so,
there are particular (and tedious)
ways of starting the machine
again, which essentially involve
preserving the heat from
repeated attempted starts so the
Flight Operations 365
engine compartment can warm
up, with a ten-minute gap
between each, removing and
replacing engine blankets every
time. In case you were
wondering, cold soaking occurs
when the aircraft and fuel
become colder than the ambient
temperature, which can happen
over a cold night or at high
altitudes, and it becomes a
problem because heat is
conducted more quickly away
from precipitation, making ice
formation easier. A 737 took off
from Toronto, which was cold,
and arrived in Nassau, which
was warm, with heavy frost on
the upper wings (it was melted
by refuelling with warmer fuel).
· That frost, ice and snow has
been removed, particularly on
lift-producing surfaces. If you
leave hoar frost on the fuselage
(only if it can be seen through),
beware of flying into cloud
where more will stick. It must be
removed from where its
dislodgement could cause
ingestion, e.g. engine cowlings.
· Check particle separators as
water seepage may have frozen
inside the engine, resulting in
abnormally high N1 and JPT.
· That the skids of a helicopter
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