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degreasers, particularly alcoholbased
ones.
· That windscreens are defrosted
(if you use a mechanical heater,
keep moving it 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.
· 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 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
engine compartment can warm
up, with a ten-minute gap
between each, removing and
replacing engine blankets every
time. Just in case you were
wondering, cold soaking occurs
when the aircraft, and fuel,
becomes much 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.
· That all 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
Specialised Tasks 79
where more will stick. It must be
removed from places where its
dislodgement could cause
ingestion, e.g. engine cowlings.
· Check any particle separators as
water seepage may have frozen
inside the engine, resulting in
abnormally high N1 and JPT
readings (in a turbine).
· That the skids are not frozen to
the ground. On a solid surface,
you might be able to rock it
using the tail. Otherwise, use
the pedals with a little collective
just before takeoff.
· Unstick windscreen wipers and
moving parts (including rotors
and propellers) by hand, or you
will strain the motors.
· That control linkages and
movement are checked.
· That pitot heat is checked by
hand—don't just accept a flicker
on the ammeter.
· Water drains are not frozen.
· That carb heat operation is
checked.
Static becomes problem when it’s
cold, as snow and air can be very dry
and therefore good electrical
insulators – a helicopter can retain
its normal static charge quite
efficiently when landing on snow
(before refuelling, remove your
survival kit, so if it blows up you’ve
got something to wear after you’ve
warmed your hands in the fire).
When possible, the first start of the
day should be an external one. With
a turbine in cold weather you can
expect a lower achieved N1 before
light up with abnormally high JPT
peaks, eventually settling down lower
than normal. Oil pressure will be
slow to rise, but high after starting –
do not go above ground idle until
pressures are in the green and will
stay there as you increase the
throttle. Temperature, on the other
hand, will be very slow to rise at all,
and you want the transmission to be
at least indicating something, which
will mean the engine oil is OK as
well, as it gets hot quicker. Allow the
electrics to warm up, too – even the
knobs can get brittle.
Don't wind up to flight idle too
quickly in case you spin or yaw on
the pad (the cyclic should be
central), especially if there’s an
engineer on a ladder doing a leak
check (be careful with rotor brakes
as well). If the machine has been
frozen to the ground, one skid may
come free first and cause dynamic
rollover. If it has not already been
freed, pull collective until ready to
lift and crack it free with a little
controlled pedal movement, though
on a big machine you might want to
use engine torque for the same
effect, otherwise you might bend the
tail boom. You could also try gently
circulating the cyclic, or pulling
down on the tail boom before
starting if the machine is light
enough. Taxi slowly with caution if
the taxiways are clear of snow. If
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本文链接地址：
The Helicopter Pilot’s Handbook(53)
