TM 1-1520-238-10
Change 9
2-48.3/(2-48.4 blank)
(b) Severance engagement.
1 The crewmembers will most likely dis-
cover the aircraft to be in BUCS after the flying pilot moves
the controls enough to satisfy the mistrack engagement
criterion causing the MASTER CAUTION light and BUCS
ON and ASE (ASE not applicable for collective) caution/
warning lights to illuminate.
2 Fly the aircraft. Some control will be
available immediately and full control will be phased in
over a one (1) second period.
(3) BUCS ON Procedures
(a) If the BUCS ON caution/warning light is il-
luminated, pilot and CPG coordinate to determine in
which station and axis (axes) BUCS is activated (affected
axis (axes) should be indicated by a disengaged SAS
channel switch(s) and an ASE caution/warning light illumi-
nation; if no SAS channel switch(s) are disengaged and
the ASE caution/warning light is not illuminated, the sev-
erance is in the collective control system) and transfer
control as necessary.
(b) Perform aircraft emergency procedure for
BUCS ON.
(4) BUCS FAIL Procedures
(a) If the BUCS FAIL light illuminates, avoid
rapid or erratic flight control inputs.
(b) Pilot attempt to reset the BUCS FAIL by
toggling the appropriate SAS channel on the ASE panel.
(c) Perform aircraft emergency procedure for
BUCS FAIL.
g.
BUCS FD/LS.
BUCS is monitored continuous-
ly. If a BUCS failure is detected, BUCS will not engage in
the affected axis and the BUCS FAIL warning light in each
crew station illuminates. To assure that BUCS is fully op-
erational, a preflight self-test is provided in addition to the
on-command DASE FD/LS test. The self-test verifies the
integrity of BUCS before starting engines. The BUCS self-
test requires primary hydraulic pressure within normal lim-
its, RTR BRAKE switch set to BRAKE, flight controls cen-
tered, collective friction off, both PWR levers in the IDLE
position or below, the helicopter on the ground and BUCS
not engaged. All DASE channels must be off.
h.
Control Locks.
The control locks protect the
shear pins in the pilot and CPG cyclic longitudinal and lat-
eral SPADS, and pedal directional SPADS (fig 2-25) from
accidental breaking when the helicopter is on the ground
without hydraulic power. They consist of two rig pins to
prevent cyclic longitudinal and lateral movement and two
pedal lock fixtures to prevent pedal movement, one set for
the pilot station and one for the CPG station.
The two sets, comprising four rig pins and four pedal
locks, are in a pouch located in the crew station. Each rig
pin and pedal lock are attached together by a lanyard with
a warning streamer.
CAUTION
When installing and removing the con-
trol locks, hydraulic power must be on
the helicopter to prevent damage to the
SPAD shear pins.
One rig pin is installed in the left side of the cyclic stick
base to prevent longitudinal movement. The other rig pin,
to prevent lateral movement, is installed in the lower right
side of the cyclic stick shroud cover where it has been cut
away to allow access for rig pin installation.
After each pedal is moved forward, the pedal lock fixture is
installed through the brushes and cutout in the floor so it
rests on the edge of a shelf. The pedal lock fixture is
aligned so that when the pedal is moved aft, the pedal
support fits into the fork of the pedal lock fixture. The pedal
is then moved aft so the fork tightly engages the pedal
support to prevent movement and the pedal adjust is tight-
ened.
