From the forward sector, the cables extend back
through the aircraft to the aft cable sector. They have
been reduced in length so that the remaining essential
components of the elevator control system may all be
shown in one drawing.
The aft sector is essentially the same as the
forward sector, and it acts as a slave to the forward
sector. Cables from the forward sector attach to the
aft edges of the aft sector. A push-pull tube from the
aft sector conncts to the elevator fitting assembly.
The elevator fitting assembly, commonly called
the elevator “horn,” is built onto the elevators and
extends outward (and usually downward) from the
elevator surface at right angles to the plane of rotation
and the chord line of the elevator surfaces. As the
fitting assembly is moved fore or aft, the elevators are
moved up or down.
HYDRAULICALLY OPERATED FLIGHT
CONTROL SYSTEM
Power-boosted flight control systems are used on
high-speed jet aircraft. Aircraft traveling at or near
supersonic speeds have such high airloads imposed
upon the primary control surfaces that it is impossible
for a pilot to control the aircraft without
power-operated or power-boosted flight control
systems. In the power-boosted system, a hydraulic
actuating cylinder is built into the control linkage to
assist the pilot in moving the control surface. The
power-boost cylinder is still used in the rudder control
system of some high-performance aircraft; however,
the other primary control surfaces use the full
power-operated system.
In the full power-operated
system, the force necessary to operate the control
surface is supplied by hydraulic pressure. Each
movable surface is operated by a hydraulic actuator
Figure 9-2.—Hydraulically powered elevator control system.
9-2
