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until the speed reduces to below 5 knots, and the helicopter
settles into the water. At zero groundspeed,
slowly lower the collective into the full down position.
Lowering the collective or leveling the helicopter too
quickly may result in the floats tucking, which can
cause the helicopter to capsize.
Caution: The following discussion deals with landing
in heavy seas. Use these procedures only in an
emergency.
Landing the float helicopter becomes risky when the
height of short, choppy waves exceed one half the
distance from the water to the helicopter’s stinger, and
the distance from crest to crest is nearly equal to or less
than the length of the helicopter. These waves cause
the helicopter to pitch rapidly and may bring the rotor
blades in contact with the tail boom or the tail rotor in
contact with the water. In addition, avoid landing
parallel to steep swells as this could lead to dynamic
rollover. [Figure 9-5]
If landing on waves higher than half the distance from
water to stinger, the following techniques apply:
• Land the helicopter 30º to 45º from the direct
heading into the swell. This minimizes the fore
and aft pitching of the fuselage, reducing the
possibility of the main rotor striking the tail
boom, or the tail rotor contacting the water. This
also minimizes the possibility of dynamic
rollover.
Perpendicular to Swell
Parallel to Swell
Angled 30° to 45°
to Swell
Rotor Strikes
Tail Boom
Dynamic
Rollover
Tail Rotor
Strikes Water
Figure 9-5. Effect of landing heading relative to waves.
Ch 09.qxd 8/25/04 11:32 AM Page 9-5
9-6
• When landing with power, maintain rotor r.p.m. in
the normal operating range. This permits a quick
takeoff if the helicopter begins to pitch excessively
or when an especially high wave becomes
a hazard.
• When landing without power in high wave
conditions, hold the desired heading as long as
directional control permits. As the rotor r.p.m.
decreases to the point that the desired heading
cannot be maintained, bring the rotor to a stop as
quickly as possible to avoid rotor contact with the
tail boom.
AUTOROTATION
An autorotation to water is similar to one performed on
a hard surface except that during touchdown, the
helicopter is kept in a slight nose-high position. For
greater safety, slow to around 5 knots of forward speed.
However, if this is not possible, maintain a slight
nose-high attitude and full-up collective to allow the
floats to plane until the speed decelerates below 5
knots. As the helicopter settles to the surface and slows
to zero knots, level the helicopter with cyclic and lower
the collective. Do not lower the collective or level the
helicopter until the speed has reduced sufficiently or
the floats may tuck causing the helicopter to capsize.
Hold a pitch attitude that keeps the tail from contacting
the water.
Autorotations to smooth, glassy water may lead to
depth perception problems. If possible, try to land near
a shoreline or some object in the water. This helps in
judging altitude just prior to touchdown.
SHUTDOWN AND MOORING
Although a helicopter can be moored prior to
shutdown, it is preferable to fly to a landing spot on the
dock or shore prior to shutting down. The helicopter
can then be parked there. If mooring is the only option,
be aware of any posts or pillars that might extend above
the main dock level. Even though there may be plenty
of blade clearance when the rotor is at full r.p.m., blade
droop due to low r.p.m. could cause the blades to come
into contact with items on the dock. Also be aware of
wind and waves that could tilt the helicopter and cause
the blades to contact objects. If near an ocean or large
body of water, tides could change the water level
considerably in just a few hours, so anticipate any
changes and position the helicopter to prevent any
damage due to the changing conditions.
When mooring the helicopter prior to shutting down,
arrange the mooring lines so the tail cannot swing into
objects once the rotors stop. Some pilots prefer to moor
the helicopter nose in to protect the tail rotor.
If there is sufficient room to allow for drift and
possible turning or weathervaning, the helicopter may
be shut down on open water, but wind and water currents
may move the helicopter a considerable distance.
When shutting down on open water, do so upwind or
upcurrent and allow the helicopter to drift to the mooring
buoy or dock. It might be necessary to use a paddle
　
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