Day 2 Lecture Flashcards
General Aviation Aircraft
Uses electric motors (reversible)
Electric Retraction Systems
Some General Aviation Aircraft
Uses a “Power Pack”
Powers one system (retraction/extension) with hydraulic pressure
Light Aircraft Hydraulic Retraction Systems
Most common Modern Corporate and Transport Aircraft
Uses pressure from main hydraulic system
Hydraulic Retraction Systems
In turn drives two torque tubes that are connect to main gear actuators
Duplex chain drives the nose gear
Limits switches are adjacent to torque tubes to ensure motor rotation will stop at desired travel
Gear Motor drives the gearbox
Engaging emergency handle to manually turn the gear box
All Aircraft MUST have a mean of alternate extension
Emergency Extension
Located on main gear housings and connect to the torque links (apart of alignment)
When weight is on the wheels the switch will open prevent retraction on ground
May be used for several functions besides retraction system
ie Outflow valve, Cabin Door operations….
May be called “WOW”, “Weight on Wheels”, or “Safety Switch”
Squat is used on ALL retraction systems
Squat Switch
USED ON ALL RETRACTION SYSTEMS
Warning System
Limit Switches
Lights
Throttle Pulled back (to predetermine setting) microswitches trigger warning horn if landing gear are in unsafe position
Warning System
Placed next to locking mechanisms to show pilot where landing gear is located
Microswitch or Proximity
Limit Switches
Green (safe to land) landing gear down and locked
Red (unsafe to land) can mean transition or up and locked depending on aircraft type.
Lights
Closed Center System – Solenoid valves direct pressure
Actuator located at each gear
Pressure switch set to shut motor off at desired system pressure
Operation
Hand Operated Pump for alternate extension if motor fails
Some may require a emergency extension valve that will open all lines to allow the gear to “free fall”
Emergency
Similar to mechanical retraction
Uses a electric driven hydraulic pump in “Power Pack”
Light Aircraft Hydraulic Retraction
Uses pressure from Main Hydraulic System
Multiple actuators
Problem for smooth extension of gear due to weight of the trucks
Most current systems – flow limiting devices
Reduce shock loads during free fall
Keep gear together extension and retraction
Emergency (alternate)
Free fall
Sometimes a nitrogen burst (gulfstream)
Transport Hydraulic Retraction System
Items that can be adjust for proper operation of landing extension and retraction
Doors
Linkages
Push pull rods
Actuators
Locks
