rotor brake. To do this, use the GUST LOCK-
gearing, unlocks its respective blade by pulling out
two blade lockpins.
LKD-UNLKD switch on the miscellaneous switch
Once the blade lockpins pull out, worm
panel. The switch enables the index unit to extend
gearing drives a segment gear, which folds back
and engage the rotor brake disk, without applying
each blade. Switches on each blade sense when
power to the index motor. A brake and gear train
the blade lockpins pull out and each blade reaches
inside the motor prevents motor output shaft
a folded position. When all four blades actuate
rotation with no power to the motor. The index
the bladefold switches, a signal goes from logic
unit effectively acts as a lock to hold the rotor
in the distributor. This signal flows through the
head in place.
slip ring to the bladefold control panel, bringing
Power goes to the GUST LOCK switch from
on a FOLDED status light.
No. 2 dc primary bus interlocked through
Each blade has individual logic circuits in a
weight-on-wheels and transmission low oil
bladefold module. Should any individual logic
pressure relays, so the GUST LOCK can only
circuit fail, the associated blade will not fold. This
engage on the ground. When the index unit
does not affect the other blades in the system, and
actuator retracts fully, a limit switch within the
they will fold normally. A spread blade can fold
actuator activates a second relay inside the panel.
This relay turns on a GUST LOCK caution light
If a loss of command signals or power occurs,
on the caution advisory panel.
this will prevent all blades from folding. A cycle
DC power extends or retracts the index unit.
caution logic circuit incorporated in the distributor
Three-phase ac power operates the index motor.
monitors failures that are common to all blades.
When the rotor head is indexed, logic circuits
The cycle caution output goes to test points in the
in the bladefold control panel turn on an
bladefold module for troubleshooting and fault
INDEXED status light. The logic also senses the
isolation of the system.
condition of the main rotor blades, tail pylon,
stabilator, and rotor brake. If main rotor blades
are spread and indexed, pylon and stabilator are
in flight position. With the rotor brake on, a pitch
You accomplish main rotor blade spreading
blades command goes to the DAFCS computer.
by setting the BLADEFOLD switch to SPREAD.
The computer flashes the BAR ALT push-
The switch routes a spread command through the
button legend on the AFCS CONTROL panel.
slip ring to the blade deice distributor. The spread
When the operator presses this push-button for
command also goes to the junction box and
2 seconds, the TRIM push-button legend goes on.
energizes a relay. This causes the power to the
This causes the computer to send flight control
distributor circuits to reverse phase, allowing the
positioning signals to the pilot-assist servos. The
bladefold actuators to run in the spread direction,
pilot-assist servos move the flight controls to a
spreading each rotor blade. As each blade reaches
computer memorized position.
the full spread position, two blade lockpins drive
With controls positioned, the computer sends
into the blade hinge lugs.
an enable signal to the pitchlock logic in the
Two switches sense lockpin positions. When
bladefold control panel indicated by the flashing
both switches actuate, a relay in the distributor
TRIM push-button legend. The control panel
energizes and reverses the phase of power to the
delivers a pitchlock command through the slip
actuators. The actuators run in the fold condition
ring to the bladefold deice distributor. This power
again for a brief period. This relieves stresses built
goes to the distributor for pitchlock actuators and
up on the segment gear in each bladefold actuator.
bladefold actuators. This 115-Vac power also goes
Running the actuators in the fold direction
to the pitchlock actuator on each rotor blade hub.
causes the blade lockpins to back slightly out of
Each actuator advances a Iockpin that locks each
the hinge lugs. One of the blade lockpin switches
blade pitch control horn.
actuates before the other. This switch remains
When all control horns lock, a signal goes
actuated even though the lockpins are backing out
through the slip ring to the bladefold control
of the hinge lugs. The other switch deactuates
panel. This turns on a PITCH LOCKED status
when the lockpins back out. When one lockpin
switch actuates, and the other is deactuated,
As each blade's pitch lockpin engages its
distributor logic determines achievement of the
full spread condition. This de-energizes the
respective pitch control horn, the bladefold
bladefold motor actuator on each blade.
actuator operates. Each actuator, through