曝光台 注意防骗
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panel on the aft fuselage.
Figure 6-6-7. Cargo Door and Ramp
TM 1-1520-240-10
6-6-15
Figure 6-6-8. Ramp Controls
TM 1-1520-240-10
6-6-16
CAUTION
Do not press the sequence valve plunger
unless the ramp is down.
6-6-24. Ramp Control Sequence Valve.
A mechanically operated sequence valve controls the
sequence of the cargo door and ramp operation (fig.
6-6-9). The valve is below the ramp control valve at the
ramp hinge line. A plunger on the top of the valve is
manually pressed to hold the cargo door at full open
during ramp operation. The plunger can be locked in the
depressed position by rotating a retainer pin which extends
from the side of the valve.
6-6-25. Pressure Actuated VAlve.
Ramp operation is stopped during cargo door operation
by a hydraulic pressure actuated valve. The valve is
locked near the ramp control valve (fig. 6-6-8). A plunger
provides manual override of the valve if it sticks.
6-6-26. Accumulator Gage.
A gage at station 534, right side indicates APU accumulator
pressure in psi (fig. 6-6-8). A pressure reading on
the accumulator gage in excess of 2,500 psi is sufficient
for operating the ramp.
6-6-27. Equipment Loading and Unloading.
The following procedures should be observed in preparing
the helicopter for cargo transport mission:
a. Doors — Open.
b. Parking brake — ON.
c. Troop seats — Stow.
d. Cargo compartment — Clean.
e. Tiedown devises — Check, for type and quantity.
f. 10,000 lb tiedown fittings — Install as required.
g. Loading aids — Check, for condition and operation.
h. Weight and balance data — Check.
i. Emergency equipment — Check.
j. Emergency exits — Inspect.
k. Cargo load — Inspect.
6-6-28. Ramp Operation.
6-6-29. Normal Operation.
WARNING
When the RAMP PWR switch is OFF, be
sure the RAMP CONTROL VALVE remains
at STOP. If the RAMP CONTROL VALVE is
moved to UP or DN, the ramp may free fall.
1. Lower the ramp as follows:
a. RAMP PWR switch — ON.
NOTE
Perform step b. and c. only if the ramp is lowered
with accumulator pressure.
b. APU accumulator gage — Check 2,500
psi or more. If pressure reading is below
2,500 psi, operate the hand pump to
build up pressure.
c. EMERG UTIL PRESS valve — Open.
Figure 6-6-9. Sequence Valve Operation
TM 1-1520-240-10
6-6-17
d. Ramp control lever — DN, allowing
ramp to lower to a position of ground
rest, then STOP. If the ramp is to be
adjusted to a level other than ground
rest, or fully closed, with the cargo door
in the retracted position, perform the
following:
(1) Sequence valve plunger — Press
and hold.
(2) Sequence valve plunger retainer
pin — Rotate to the horizontal position
to lock the plunger in.
2. Raise the ramp as follows:
a. Sequence valve plunger — Check, released
if ramp and cargo door are to be
closed.
NOTE
Perform step b. only if accumulator pressure
is used to raise the ramp.
b. EMERG UTIL PRESS valve — Open.
c. Ramp control valve lever — UP, allowing
ramp to close. If accumulator pressure
is not sufficient to raise the ramp,
operate the hand pump.
d. Ramp control lever — STOP.
6-6-30. In Flight Operation.
CAUTION
Do not attempt to manually operate the
cargo door when the utility hydraulic system
is pressurized. Motor damage can result.
The ramp can be operated up to Vne. At speeds up to 60
knots, the ramp will open normally. At speeds above 60
knots. air pressure from within the cargo compartment is
required. To get this pressure, the vent blower can be
turned on or the upper section of the cabin door can be
opened.
6-6-31. Ramp Emergency Control.
WARNING
The RAMP EMER control switch is intended
for emergency use only during
smoke and fume elimination procedures.
Inadvertent operation of the cargo ramp
and cargo door from the cockpit may result
in injury to personnel or damage to
equipment.
1. Open the ramp as follows:
a. RAMP PWR switch — EMERG.
NOTE
Momentary selection of the RAMP EMERG
control switch to the DN position will result in
approximately 5 seconds of the ramp and cargo
door opening operation sequence. The
opening sequence of the ramp can be halted
during the 5 second cycle by momentarily
placing the RAMP EMER control switch to the
UP position. Continuous lowering of the ramp
(longer than 5 seconds) can be achieved by
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