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flare. Allow the RRPM to increase to the upper limit so that
maximum benefit can be gained from the inertia to cushion
the touchdown.
b. At approximately 30 feet above the water, the final
attitude should be adjusted, not to exceed 20 nose-up. An
excessive nose-up attitude will reduce the clearance between
the water and the aft rotor baldes and concentrate
impact forces on the aft fuselage.
c. R/D should be the minimum attainable at water entry
and must be considered regardless of water entry speed.
The water entry speed should be as slow as possible without
sacrificing helicopter control.
d. Helicopter attitude at water entry is very important and
relates directly to water-entry speed. At zero and up to 30
knots, the pitch attitude at water entry is dictated primarily by
the clearance between the water and the aft rotor blades
and should not exceed 20 nose-up. Entry speeds up to
approximately 40 knots require a pitch attitude of approximately
15 to prevent high concentrated impact loads on the
extreme aft bottom of the fuselage. However, it is also important
not to allow the pitch attitude to become less than
approximately 5º at the highest water entry speeds since
there is a possibility of breaking the lower nose enclosure
plastic panels.
e. The actual touchdown on the water will probably be
governed by one of the following conditions:
1. High wind and rough water. Use thrust as
necessary to minimize R/D at water entry. Do
not hesitate to use the remaining thrust at
water entry if the R/D is judged to be
excessive.
2. Low wind and calm water. Follow the pro–
cedure above to the point of the deceleration.
Reduce speed to approximately 40 knots and
then establish a nose-up attitude of
approximately 5 to 10. Just prior to water
entry, increase thrust to cushion the aft landing
gear contact with water. Attempt to havr the
R/D as low as possible when using this
technique. As the helicopter decelerates,
attempt to hold the nose out of water. As the
speed diminishes to 10 knots or less, lower the
thrust control smoothly and return the controls
to neutral. The helicopter does not display any
tendency to pitch down upon water entry. Also,
the aft landing gear acts to create a
decelerating force on the water. If ditching
becomes necessary:
AUTOROTATE
9-1-71. Landing With One Engine Inoperative.
When committed to a S/E landing, it is sometimes possible
to terminate the approach at a hover; however it is recommended
that a running landing or an approach which terminates
on the ground be used if terrain conditions allow.
9-1-72. Landing in Trees.
External cargo must be jettisoned as soon as possible. If a
landing in trees is imminent, it is important to stop the forward
motion of the helicopter before entry into the trees.
Power on:
1. Approach to a hover — 5 to 10 feet.
2. EMER ENG SHUTDOWN.
3. AUTOROTATE.
Power off:
AUTOROTATE.
TM 1-1520-240-10
9-1-28
Figure 9-1-9. Ditching Exits
9-1-73. Flight Controls.
9-1-74. Longitudinal Cyclic Trim (LCT) System
Failure.
Should the system fail during cruise, with the cyclic trim
system programmed for maximum forward tilt of the rotors,
an abnormal nose-up attitude will result with decreasing
airspeed. Should one or both cyclic actuators
fail in full retract position, airspeed must be limited according
to Vne for retracted longitudinal cyclic trim. With
both LCTs partially or fully retracted, maintain below Vne
and if failure occurs extended, maintain airspeed at or
above 60 KIAS or until the approach to landing. Should
the longitudinal cyclic trim system fail, perform the following:
CYCLIC TRIM circuit breakers — In. If cyclic trim operation
is not restored, proceed with the procedures below
for AUTO or MANUAL modes of operation.
If in AUTO mode:
1. Airspeed — Adjust.
2. CYCLIC TRIM switch — MANUAl.
3. FWD and AFT CYCLIC TRIM switches —
Adjust for airspeed.
If LCT operation is not indicated:
FWD and AFT CYCLIC TRIM switches — RET for 30
seconds, before landing.
If in MANUAL mode:
1. Airspeed — Adjust.
2. CYCLIC TRIM switch — AUTO.
If normal LCT operation is not indicated:
1. CYCLIC TRIM switch — MANUAl.
2. FWD and AFT CYCLIC TRIM switches —
RET both LCTS for 30 seconds, before landing.
If both actuators are retracted, the landing will be normal.
If one or both actuators fail in extended position, the pitch
atitude of the helicopter will be higher than normal during
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