TM 1-1520-238-T-7
11–15
11–2.
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (cont)
11–2
d. Lateral (Cyclic) Flight Control System.
The lateral (cyclic) flight control system (fig. 11–4) consists of
the pilot and CPG cyclic sticks, two LVDTs, two SPADs, feel spring and magnetic brake assemblies, lateral
mechanical control linkage, lateral servocylinder, mixer assembly, two lateral links, torque link, swashplate
assembly, pitch link assemblies, and scissor assemblies.
(1) Pilot and CPG Cyclic Sticks.
The pilot and CPG cyclic sticks, mounted to the floor centerline in
each crew station, control the main rotor assembly for longitudinal and lateral flight of the helicopter. The cyclic
sticks control lateral flight by left and right movement. If mechanical control is lost, BUCS will maintain longitudinal
and lateral control. The cyclic stick consists of a grip, tube, base, housing, and support assembly.
(a) The grip assembly, mounted at the upper end of the cyclic stick assembly, is a handle used to
control the cyclic stick which contains various switches and controls.
(b) The tube assembly is the controller for the cyclic control system and is mounted to a fitting
assembly, which is supported by the lock and base assemblies. The tube assembly has five welded pieces
consisting of a tube, fitting, cover, guide and support. The upper portion mounts to the grip assembly, while the
lower portion mounts to the fitting assembly. A cable assembly is mounted to the upper portion of the tube
assembly and releases the lock assembly in the retracted position. The fitting assembly is mounted to the lower
portion of the tube assembly to provide mounting for the tube assembly and attachment of the lock assembly. The
lock assembly is mounted between the fitting assembly and the base assembly to allow the cyclic stick assembly
to be locked in the extended or retracted position.
(c) The base assembly, located at the lower portion of the cyclic assembly, provides mounting of the
lock assembly and the lateral pivot point. Links and levers are located and mounted to the fitting, lock assembly,
and the base assembly to provide interconnection between the finger lock release lever and cable assembly, to
actuate the lock assembly.
(d) The housing assembly, mounted to the support assembly at the floor centerline in each crew station,
provides longitudinal and lateral control movement of the cyclic stick assembly.
(e) The support assembly, mounted to the floor centerline in each crew station, provides mounting and
support for the housing assembly and the lateral SPAD.
(2) LVDTs.
One lateral and one longitudinal LVDT is installed at the canted bulkhead and at the base of
the cyclic stick assembly in each crew station. The LVDTs generate electrical signals that are proportional to the
amount of cyclic stick movement. The LVDT sends a signal to the DASEC proportional to its movement.
(3) SPADs.
The lateral and longitudinal SPADs are attached to the cyclic output bellcrank assembly at
each crew station. The SPADs activate the fly-by-wire BUCS system if the mechanical flight controls are jammed
and the shear pin is severed. The SPAD incorporates a mechanical cam lock, 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.
(4) Feel Spring and Magnetic Brake Assemblies.
The feel spring and magnetic brake assemblies are
installed beneath the pilot’s cyclic housing assembly, one set provides longitudinal and lateral flight trim for both
stations.
(a) The feel spring assembly is a spring loaded device which overrides the magnetic brake when locked
by moving the cyclic stick against the spring.
