ROTARY-WING MAINTENANCE
close. The pilot valve clevis will be in the center of the
sloppy link. When pressure is off, the bypass valve will
LEARNING OBJECTIVE: Identify general
open, preventing hydraulic lock.
rotary-wing maintenance procedures to
include system rigging and rotor blade
Swashplate Assembly
tracking.
The swashplate assembly, shown in figure 17-9,
Organizational maintenance of the helicopter flight
s e n d s m ove m e n t o f t h e f l i g h t c o n t r o l s t o t h e
control system includes periodic inspection, lubrication,
rotary-wing blades. A ball ring and socket allows the
rigging, and blade tracking. It also includes the cleaning
swashplate to tilt off its horizontal plane and move on
of the rotary-wing and rudder blades and the removal and
its vertical axis.
replacement of malfunctioning components.
The assembly consists of a rotating swashplate,
Organizational maintenance of the auxiliary and
connected to the rotary-wing hub by the rotating
primary servo cylinders is limited to minor adjustment
scissors and adjustable pitch control rods. The
and replacement of miscellaneous seals. Organiza-
assembly also has a stationary swashplate, which
t i o n a l m a i n t e n a n c e i n c l u d e s t h e r e m ova l a n d
connects to the main gearbox by the stationary scissors
installation of the complete component. Major
and the primary servo cylinders. Each swashplate
adjustments made on servo cylinders during overhaul
are critical. These adjustments are not made at the
assembly is bolted together in a way that permits the
lower levels of maintenance.
rotating swashplate to rotate within the stationary
swashplate. When the primary servo cylinders are
Vi b r a t i o n s a n d c y c l i c a c t i o n s i n h e r e n t t o
actuated by the flight controls, the stationary
helicopters can cause component or structural fatigue.
s wa s h p l a t e m ove s , w i t h t h i s m ove m e n t b e i n g
Nondestructive testing (NDI) is used on many parts of
transmitted to the rotating swashplate. The rotating
the airframe and many dynamic components to detect
swashplate sends movement, through the adjustable
flaws (cracks) that could lead to failure. Additionally,
pitch control rods, to the sleeve spindle of the rotary
most of the dynamic components, such as rotor heads,
blades, servo cylinders, and swashplates, have forced
blades. This action changes the angle of incidence of
(high-time) removal intervals. These time intervals are
the blades.
listed by component in the Periodic Maintenance
Q17-17. What pitch control system provides lateral
Information Cards (PMIC) for the aircraft.
helicopter movement?
You should clean the rotary wing and rotary rudder
Q17-18. What pitch control system provides vertical
as necessary, using only approved cleaners. The
helicopter movement?
concentration of mixture will vary, depending on the
Q17-19. What does the rotary rudder system control?
surface condition and type of cleaner used.
Q17-20. On the rotary rudder control system, what
CAUTION
component is preloaded to 600 pounds and
considered hazardous to personnel?
Both the rotary-wing and rudder blades have
areas that connect by bonding adhesives or they
Q17-21. H o w m a n y s e p a r a t e b a n k s o f
are manufactured out of fiber glass or advanced
servomechanisms make up the auxiliary servo
composite materials. Never use solvents or
cylinder?
cleaners not specifically authorized in the MIM.
Q17-22. What component controls and transfers
Do not use lacquer thinner, naphtha, carbon
independent movements of the lateral,
tetrachloride, or other organic compounds for
forward, aft, and directional controls?
cleaning in these bonded areas. Use of these
Q17-23. The movement of what valve allows hydraulic
solvents or cleaners may result in blade failure.
f l u i d f l o w i n t h e t h re e p r i m a r y s e r v o
cylinders?
SYSTEM RIGGING
Q17-24. What unit sends movement, through the
adjustable pitch control rods, to the sleeve and
Rigging checks and adjustments involve the cyclic
spindle assembly of the rotary blades to
pitch control stick, collective pitch control stick, and
change the angle of incidence of the blades?
pedal positions. These controls must coordinate with
17-10
