STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS
Landing Gear Normal Extension
Placing the handle to the DN position electrically positions the gear door selector valve to the
door open position. When both gear doors are closed and locked, hydraulic pressure to the door-
actuating cylinder is shut off. The landing gear extension cycle requires approximately seven
Landing Gear Retraction
Placing the handle to the UP position electrically positions the gear door selector valve to the UP
position. When the fuselage main landing gear doors close and lock, hydraulic fluid to the door
actuating cylinders is shut off. All uplock assemblies are mechanically moved to the locked
position. The retraction cycle takes approximately seven seconds.
Emergency Gear Extension
The landing gear can be lowered by gravity using the emergency gear extension system. Pulling
the EMER L/G DOWN handle releases the main gear door uplocks, the main gear uplocks, and
the nose gear uplock (the handle must be pushed down, then pulled out to approximately 10
inches). Once the landing gear doors open and the landing gear free falls to the down-and-
locked position, stow the handle.
In the event of an emergency gear extension the main gear doors must be raised using pneumatic
pressure through actuation of the EMER DOOR CLOSE handle. Pulling this handle out will
direct pneumatic pressure from the nitrogen bottle to the main gear door actuating cylinders,
which close the doors in approximately three seconds and extinguishes the red UNLOCKED
light. The handle is spring-loaded, and will stow when released.
Landing Gear System Controls and Indicators
Landing Gear Handle
The handle placarded LDG GR is a manually operated control which electrically controls the
position of the landing gear. A solenoid operated locking mechanism is provided to prevent
accidental movement of the handle when the aircraft is on the ground. In flight, the solenoid
releases the handle locking mechanism.
Emergency Landing Gear Down Handle
The emergency gear extension T-handle is located beneath the P's instrument panel. It is safety
wired and placarded EMER L/G DOWN.
Emergency Door Close Handle
The EMER DOOR CLOSE handle is located beneath the P's instrument panel. It has a red knob
placarded PULL, and is safety wired.
5-6 HYDRAULIC POWER SUPPLY & SYSTEMS