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in snow, it is vital to select a reference point to
maintain situational awareness and take off directly to
a high hover at an altitude that allows visual contact to
be maintained. When performing a hover taxi, select
the speed just above effective translational lift to help
keep the blowing snow behind the helicopter. If loose
snow is less than 6 inches, it may be possible to apply
collective pitch to create enough rotorwash to blow
away the majority of the snow before lift-off. If
moving the helicopter a short distance, and especially
when around other aircraft, it might be preferable to
surface taxi on the skis.
When taxiing wheel-equipped helicopters on snow and
ice, use caution when applying the brakes. If the
helicopter begins to skid sideways, lower the
collective, which places all of the weight on the wheels
and move the cyclic in the opposite direction of the
skid. If the skid continues, the best option at that point
is to bring the helicopter into a hover, but be aware of
objects that could lead to a dynamic rollover situation.
TAKEOFF
Normal takeoff procedures are used in snow and ice,
but before startup, check the departure path for any
obstructions that may be obscured by blowing snow.
Powerlines are difficult to see in the best conditions
and nearly impossible to recognize through blowing
snow.
Perform a takeoff from a hover or from the surface by
fairly quickly increasing speed through effective
translational lift and gaining altitude in order to fly out
Figure 9-6. Ski equipped helicopter.
Ch 09.qxd 8/25/04 11:32 AM Page 9-7
9-8
of the low visibility conditions. A takeoff from ice
requires slow application of power and proper pedal
application to prevent spinning. At certain temperatures,
the skis may freeze to ice surfaces. If this occurs,
a slight left and right yawing with the pedals may break
the helicopter free. If this does not free the skids, shut
down the helicopter and free them manually. Excessive
pedal application could damage the skids.
LANDING
As with takeoffs, landings in snow can prove to be
extremely hazardous if reference points are not
available. When possible, land near objects that won’t
be easily obscured by blowing snow. If none are
available, drop a marker made from a heavy object,
such as a rock tied to a colored cloth; then retrieve it
after landing.
When the snow condition is loose or unknown, make a
zero-groundspeed landing directly to the surface
without pausing to hover. A shallow approach and
running landing can be performed when the snow is
known to be hard packed and obstacles are not hidden
under the snow. The lower power required in a running
landing reduces the downwash and the forward motion
keeps blowing snow behind the helicopter until after
surface contact.
If the surface conditions are unknown, a low reconnaissance
flight might be appropriate. This could be
followed by a low pass. A low pass might blow away
loose snow and keep the debris behind the helicopter. If
the surface appears appropriate for a landing, make an
approach to a high hover to blow away any remaining
loose snow and begin a vertical descent to the landing.
If the surface appears to be deep hard-packed snow or
ice, lower the collective slowly on landing and watch
for cracking in the surface. Should one skid break
through the surface, a dynamic rollover is likely to
follow, so be prepared to return to a hover if the
surface is unstable.
Skis are also very useful for landing on uneven or soft,
spongy surfaces. They provide a larger surface area to
support the helicopter, thus assisting in stability. Be
sure that the skis are not hooked under roots or brush
during lift-off.
AUTOROTATION
Use normal autorotation procedures in ski equipped
helicopters. Perform practice autorotations on snow or
sod to reduce the wear on the skis.
GROUND HANDLING
Shut down before loading and unloading. If shutting
down is not feasible, load and unload passengers only
from the front during snow and ice operations. This
prevents the main rotors from striking an individual
should one landing gear drop through the snow or ice.
Beware of loading and unloading while running in
deep snow as the rotor clearance is reduced by the
height of the snow above the skids.
Most skis for skid-equipped helicopters allow use of
standard or slightly modified ground handling wheels.
Skis for wheel-equipped helicopters often have
cutouts to allow the wheels to protrude slightly below
the ski for ground handling.
　
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