proof loads for testing various size cables are given in
tables contained in NAVAIR 01-1A-8. Proof loading
will result in a certain amount of permanent stretch
being imparted to the cable. This stretch must be
taken into account when You fabricate cable
assemblies. Cables that are made up slightly
may be entirely too long after proof loading.
SECONDARY FLIGHT CONTROL
SYSTEMS
long
Learning Objective:
Recognize the varied
functions of secondary flight control systems
and the maintenance associated with each
system.
Secondary flight controls, such as wing flaps and
speed brakes, are usually hydraulically operated and
either mechanically or electrically controlled. The
design of these flight controls slows the aircraft in
flight and provides additional lift and stability. These
design features greatly increase the versatility and
performance of the aircraft.
CONVENTIONAL WING FLAP SYSTEM
A flap is a hinged or pivoted section that forms the
rear portion of an airfoil used to vary the effective
chamber. Wing flaps in their most commonly used
form are hinged sections of the trailing edges of a
wing. Flaps extend from the fuselage to the inboard
side of the aileron. Wing flaps are connected to the
main wing by various kinds of hinges and slides.
The flap system discussed in this section is a
representative system. The number of flaps will vary
according to the size of the aircraft. The components
may have different names, depending on the
manufacturer, but the operational theory remains the
same. This system consists of a series of six flaps, three
on the trailing edge of each wing. They raise and lower
in the conventional manner by a hydraulically actuated
linkage of bell cranks, pushrods, and idlers. The flap
control lever in the cockpit controls the system
mechanically. The lever connects by conventional and
teleflex cables to the hydraulic actuating mechanism.
An emergency system is provided for lowering the flaps
by operating a hand pump if the primary system
malfunctions. The flap system has a position indicator
and several safety devices to prevent lowering of the
flaps while the wings are folded, or folding of the wings
while the flaps are lowered.
The movement of the flap selector lever in the
cockpit sets the flaps in motion. Movement of the
selector lever operates a cable quadrant to which a set
of conventional control cables attach. These cables
connect to another sector just forward of the main
wing beam. A teleflex cable, also attached to this aft
sector, and a spring-loaded pushrod on the main flap
actuating bell crank connect to the two ends of a short
floating arm installed on the hydraulic selector valve
lever. Figure 9-32 is a drawing of the cylinder,
linkage, and selector valve installation. Reference to
the index numbers on this drawing is made in the
following description of the operation of the flap
control system.
1. Wing flap cylinder
4.
2. Wing flaps selector valve
5.
3. Flap actuating bell crank
6.
Left flap control pushrod
7. Follow-up pushrod
Right flap control pushrod
8. Flap position transmitter
Flap control push-pull cable assembly
9. Selector valve floating arm assembly
Figure 9-32.—Flap cylinder, linkage, and selector valve installation.
9-37
