or GEAR DOWN position. It is energized to the
door-close position by main gear-operated
switches when the gear is fully retracted
or extended.
The landing gear control valve is energized to
extend or the retract position by switches located
on the gear door actuators sensing the full open
position of both main gear inboard doors.
During retraction, the circuit is completed
through both squat switches to ensure that the
airplane is off the ground prior to the valve
being energized.
Normal Retraction
Positioning the landing gear selector switch to
GEAR UP energizes the door control valve to
the open position, directing hydraulic pressure to
release the main gear inboard door uplatches and
to open the doors. The two main gear red
UNSAFE lights illuminate simultaneously with
uplatch release.
When the inboard doors are fully open, the door-
open switches are actuated. This energizes the
gear control valve to the retract position, and
hydraulic pressure is directed to retract the land-
ing gear (Figure 14-6). The three green
LOCKED DOWN lights extinguish and the nose
gear red UNSAFE light illuminates.
When the gear has fully retracted, the nose gear
red UNSAFE light extinguishes. When both
main gear are fully retracted, switches are actu-
ated and complete circuitry to energize the door
control valve to the closed position. Hydraulic
pressure closes the gear inboard doors, which
lock in position by spring tension on the door
uplatches, and the two main gear red UNSAFE
lights extinguish.
Normal Extension
Positioning the landing gear selector switch to
GEAR DOWN energizes the door control valve
to the open position, thereby directing hydraulic
Figure 14-6. Landing Gear Retracted
To Next Page
Loading...
