Mechanical Control
When wing sweep is under mechanical control,
the wing sweep handle positions the wings through
the wing sweep/flap and slat control box. Because the
minimum wing sweep limiting is not available under
mechanical control, the wings can be swept to an
adverse position that could cause damage to the
wings. Mechanical control is used for emergency
wing sweep and wing oversweep.
During emergency wing sweep, the wing sweep
handle, mechanically coupled to the wing sweep/flap
and slat control box through a cable assembly,
positions the wings. The wing sweep can be returned
to electronic control by repositioning the wing sweep
handle to the stowed position.
Wing oversweep can only be obtained with the
aircraft weight on the wheels. Wing oversweep,
shown in figure 9-39, reduces the amount of space
required for spotting the aircraft. A wing sweep
self-test can only be performed while the wings are
overswept.
SPEED BRAKE SYSTEM
Speed brakes are hinged, movable secondary
control surfaces used for slowing down the speed of
the aircraft by increasing the profile drag. These
surfaces are also called “dive brakes” or “dive flaps.”
On some aircraft, they are hinged to and faired with
the side or bottom of the fuselage. On others, they are
attached to the wings. Regardless of their location,
their purpose is the same.
Fuselage Type
The fuselage speed brake system is normally
electrically controlled and hydraulically operated.
See figure 9-40. In an emergency, it can be controlled
manually.
The brake surfaces are installed on the sides of the
aft portion of the fuselage below and forward of the
horizontal stabilizer. They hinge at their forward end.
When in the closed position, they fit flush with
fuselage skin. An elevator speed brake interconnect
provides a connection between the left-hand speed
brake and the aircraft nose down elevator control
cable. When the speed brakes open, the cable pulls
and provides a nose down action to counteract the
tendency of the aircraft to assume a nose up condition.
The speed brakes may be actuated by the
two-position, spring-loaded-to-neutral control switch
on the throttle lever or by the manual override control
handle. When operating the switch to open the speed
Figure 9-40.—Speed brake control system.
9-46
