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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 accept a flicker on
the ammeter.
· Water drains are not frozen.
· That carb heat 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
Special Use Of Aircraft 235
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 as well – even
the knobs can get brittle.
Don't wind up 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
brake, too). 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 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
not, taxi higher and slightly faster
then normal to keep out of the
resulting snow cloud. If you have
wheels, act as if you have no brakes.
Marshallers should be well clear and
move slowly themselves. If the
heater is required to be off in the
hover, ensure the blower is on, to
help clear the windscreen.
Whiteout
See under Visibility.
Taking off
In snow, the accepted takeoff
method is the towering type, because
a normal one may produce a large
snow cloud to blind air and ground
crews, and a failed engine (you may
be able to blow a lot of loose snow
away with a little application of
collective before the take-off
proper). If a white-out does happen,
apply maximum collective for an
immediate climb and forward cyclic
(i.e. no hover), keeping the ball
centred and using the A/H if
necessary, but the real key is keeping
a visual reference. If you have it,
exercise the gear once or twice to
dislodge any slush, etc. that may
have stuck to the legs, to stop it
freezing. With any piston engine, use
carb heat regularly and check instrument
readings frequently for carb
icing. Have carb heat fully on or off,
but not on for prolonged periods—it
increases fuel consumption (see also
Engine Handling).
The Cruise
Mountain wave clouds can be loaded
with heavy ice at remarkably low
temperatures (remember that low
pressures and low temperatures will
cause your altimeter to read high).
When using anti-icing, take into
account the inaccuracy of the
236 Operational Flying
temperature gauges, so if you must
turn it on at 4°, and the temperature
gauge is only accurate to within 2,
start thinking about it at 6°.
Wet and sticky snow has more
chance of icing, and is associated
with low visibility, which would
indicate that you shouldn’t be flying
anyway. Luckily, light powdery snow
tends not to accumulate, but will still
give you the leans. Whatever type
you fly in, use snow baffles.
Visibility, by the way, includes the
inside! When it’s very cold, water
vapour (from clothes, breath, etc.)
will freeze on the windscreen, so
warming up the machine before
passengers get in will help a lot.
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