Hydraulics Flashcards
What is the Open Center system normally pressurized at?
60 psi
What systems are operated by the open center system
Landing gear
Speed brakes
Thrust attenuators
Flaps
When does the system pressurize to 1500 psi?
When a hydraulic component requires actuation. (One of the four systems is put in use)
Hydraulic reservoir
Mounted under right engine pylon
Pressurized by 23 psi (moves fluid to pump)
2 liters / .54 gallons
Hydraulic fluid type
MIL-H-83282
Hydraulic pumps how many gallons per minute
1.3 gal at 60 psi
3 gal at 1500 psi
Where is the hydraulic SOV located
Between pump and reservoir
What is the hydraulic SOV connected to?
Engine Fire Push Button
Flow switches/check valves
Prevents reverse flow when and if the pumps provide different pressures.
When closed, causes the HYD FLOW LOW annunciator when flow is below .35 to .55 GPM
Reopens when when above 1.33 GPM
System loading valve / system bypass valve (SBPV)
Energizes closed to operate hydraulic systems. (Closes to keep it 1500 psi)
Closes when one of the 4 subsystems are actuated.
Pressure relief cracks at 1350 psi and fully opens at 1500.
HYD PRESS ON annunciation
What do the 4 system control valves do?
Electronically de energize OPEN to begin actuation.
Electronically energize CLOSED when cycle is complete
Normal Operation Sequence
1: Pilot activates a selected subsystem
2: System bypass valve (SBPV) pressurized the system (closes valve), illuminating HYD PRESS ON annunciation
3: Subsystem control valve opens, allowing for pressurization
4: Subsystem cycle completes, showing the correct cockpit indication
5: Subsystem control valve closes,
6: SBVP opens, back to 60 psi, HYD PRESS ON annunciator extinguishes
What keeps landing gear selector from retracting on the ground
Downlock Solenoid
Main Gear
Retracts inboard
Door does not cover entire gear when retracted
3 fuse plugs
Visual pop out indicator on actuator when downlock is engaged
Nose gear (doors, degrees and shimmy)
3 gear doors
20 degrees steerable with pedals. 64 degrees with braking and diff power
Shimmy damper on top of strut