Emergency Gravity Gear Extension
If the normal system fails to extend the gear hydraulically, the flight crew can use a crank to extend it mechanically.
When a crew member turns the crank clockwise 3 turns, it:
- isolates the landing gear hydraulics from the green hydraulic system,
- opens hydraulic vent valves and unlocks doors,
- unlocks the main and nose main gear that will extend with gravity,
Locking springs help the crew to crank the main gear into the locked condition, and aerodynamic forces assist in the locking of the nose gear.
The gear doors remain open. The flight crew can reset the emergency extension system in flight after using it for training (if green hydraulic pressure is available).
See our Custom Hydraulics Guide.