CABLE AND RIGID CONTROL
In the elevator system shown in figure 9-26,
rigging begins at the aft sector.
manufacturer has determined the position of the aft
sector when it is in the neutral position. A rig pinhole
has been furnished in the sector and a mating hole in
the adjoining structure.
See the three rig pins in
figure 9-26. With the rig pin inserted in the aft sector
and in the aircraft structure, the sector is held firmly in
the neutral position. With the sector in this position,
the push-pull tube connecting the sector with the
elevator fitting assembly is adjusted to position the
elevators to the neutral position. The neutral position
is determined by using the elevator rigging fixture
shown in figure 9-27.
The curved section of the
rigging fixture is graduated in degrees on either side
of the neutral (zero degree) position that is about
midway on the curved part of the fixture.
The rigging fixture is fastened securely to the
aircraft at the indicated points of attachment. When
properly mounted, the index marks (graduations) on the
curved section align with the elevators and indicate the
position, in degrees, of the elevators. If, with the aft
sector rig pin in place, the elevators are not in neutral
(for example, 5 degrees above the neutral mark),
lengthening the push-pull rod end will push the elevator
fitting assembly forward, and thereby lower the
elevators. If the elevators are too low, then shortening
the rod will bring them up as required.
The next step is the adjusting and tightening of the
pair of cables in the system. This is accomplished by
tightening the turnbuckles on each cable evenly until
the required tension is obtained. During cable
tightening, the rig pin is retained in the aft sector,
leaving the forward sector free to turn. Therefore,
when the necessary tension is recorded on one cable,
that is also the tension on the other cable. To ensure
Figure 9-26.Typical elevator flight control system.