4I-10 Developed for Training Purposes Leerjet 35/36
February 1998
CAE SimuFlite
Extension
Placing the landing gear selector to the DN position energizes
the main gear door control valve to the down position. Hydrau-
lic pressure is directed to the door uplock actuators and door
actuators. When the doors unlock, the two main gear red
UNSAFE lights illuminate. Hydraulic pressure drives the main
gear doors to the open position. The door down switches then
actuate to energize the landing gear selector valve to the down
position.
The selector valve directs hydraulic pressure to power the nose
and main landing gear actuators. When the nose gear
unlatches, the red UNSAFE light for the nose gear illuminates.
The landing gear extends then locks. When the landing gear
locks, the the green LOCKED DN lights illuminate and the nose
gear UNSAFE light extinguishes. The door control valve ener-
gizes to the up position, the main landing gear doors close,
extinguishing the main gear UNSAFE lights.
Emergency Extension
If the hydraulic system fails or an electrical fault occurs in the
landing gear system, an emergency air bottle supplies pneu-
matic pressure to extend the landing gear. The landing gear
selector should be in the DN position to prevent inadvertent
gear retraction after emergency extension.
Depressing the emergency extension handle directs pressur-
ized nitrogen from the emergency air bottle to the nose gear
uplatch actuator, main gear door uplatch actuators, and the
nose and main gear actuators. Shuttle valves in the landing
gear hydraulic supply lines then shift to isolate the hydraulic
system from the pneumatic system. Pneumatic pressure drives
the landing gear to the down and locked position.
During emergency extension, the green LOCKED DN lights illu-
minate. The red main gear UNSAFE lights remain illuminated
because the main gear doors do not close after gear extension.
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