TM 1-1520-238-T-7
11–6
11–2.
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (cont)
11–2
b. Collective Flight Control System.
The collective flight control system (fig. 11–2) consists of the pilot
and CPG collective sticks, collective linear variable differential transducers (LVDTs), a collective 1G spring
assembly, two shear pin actuated decouplers (SPADs), collective mechanical control linkage, collective
servocylinder, mixer assembly, swashplate assembly, pitch link assemblies, scissor assemblies, a torque link, and
lateral links.
(1) Collective Stick.
The collective sticks, mounted to the left of the seat in the pilot and CPG stations,
contain various switches and controls for aircraft operation.
(a) The friction adjust twist grip, mounted below the grip assembly and forward of the friction guide,
frictionally locks the collective stick in a desired position. Rotation of the grip (counterclockwise) applies (pressure)
friction through the housing assembly to the slotted friction guide.
(b) The grip assembly, mounted at the forward end of the collective stick, is grasped as a handle for
controlling the collective stick and incorporates an engine chop and reset collar which reduces engine rpm to flight
idle in the event of an emergency situation. The collar is activated by pushing forward (to unlock) and then rotating
45 right for chop and left 45 for reset.
(c) The switchbox assembly (stabilator manual control panel) is mounted in the upper forward portion of
the grip assembly and contains various switches and controls for quick system operation.
(d) The guarded BUCS select trigger switch, mounted in the lower forward portion of the grip assembly
(CPG collective stick only) must be raised and the trigger squeezed to activate the BUCS select trigger switch to
allow control transfer of BUCS from pilot to CPG’s LVDTs.
(2) Collective LVDTs.
Two collective LVDTs are installed at the canted bulkhead and at the base of the
collective stick assembly in the pilot’s station. One collective LVDT is installed at the same points in the CPG’s
station. The LVDT sends a signal to the DASE computer (DASEC) proportional to the amount of its movement.
(3) Collective 1G Spring Assembly.
The collective 1G spring assembly is connected to each of the
collective sticks and bulkheads and provides the means of counterbalancing the weight of the collective stick. The
collective 1G spring assembly is a cylinder which contains a spring that, when compressed, exerts a force of
approximately 54 lbs.
(4) Collective SPADs.
The collective SPADs, connected to the output linkage of each collective stick,
activates the fly-by-wire BUCS system when the mechanical flight controls are jammed and the shear pin is
severed. The SPAD incorporates a mechanical cam lock, a switch, and shear pin that fits into a slot on one of the
bellcranks and locks the input and output bellcranks together as a single unit.
(5) Collective Mechanical Control Linkage.
The collective mechanical control linkage is routed through
the left side of the fuselage to the aft side of the canted bulkhead and is then routed up to the collective
servocylinder. Movement of the collective stick is transmitted through the mechanical control linkage, collective
servocylinder, mixer, torque link, lateral link, swashplate assembly and pitch links, to the main rotor blades. The
collective mechanical control linkage incorporates various bellcranks and push-pull tubes. The push-pull tubes
have steel self-centering rod end bearings containing teflon. Selected push-pull tubes have adjustable rod end
bearings for system rigging.
