Hydraulics Flashcards
Hydraulic system
Two independent systems: the primary and the utility.
Failure of the primary hydraulic system will result in the loss of BUCS and SCAS functionality.
PRIMARY HYDRAULIC SYSTEM
Provides 3000 psi to primary side of flight control servoactuators
Failure will result in FMC Disengage and BUCS Fail
Components: manifold, reservoir, pump, and GSE
Primary Hydraulic Manifold
The primary manifold stores, filters, and regulates the flow of hydraulic fluid, provides pressure, dirty filter, and low level indications. The manifold reservoir is pressurized on the return side by IPAS air acting on the manifold reservoir piston. This prevents pump inlet cavitation.
NOTE: Failure of the primary hydraulic system will result in the loss of BUCS and SCAS functionality.
Air Bleed Valve
The air bleed valve is used to deplete the pressurized air from the manifold reservoir for system repair or service.
Reservoir Low Level Indicating Switch
A reservoir low level switch is activated by the manifold reservoir piston. The PRI HYD LEVEL LOW caution displays when the minimum operating level is detected.
Pressure Sensing Switch
Pressure Sensing Switch. A pressure switch senses primary system pressure and notifies the crew of a low fluid pressure condition by displaying the PRI HYD PSI LOW caution.
UTILITY HYDRAULIC SYSTEM
Controls backup and utility side of servoactuators
Rotor brake
AWS turret
APU start motor
Ammunition handling
TW unlock
Elevation for pylons
Utility Hydraulic Manifold
The utility manifold is installed on the aft main fuselage deck on the right side. It stores, filters, supplies, and regulates the flow of utility hydraulic fluid.
Low Level and Auxiliary Isolation Valves
The low level and auxiliary isolation valves permit hydraulic fluid to flow to external stores, ammo carrier drive, and AWS turret. If reservoir fluid level decreases significantly, the reservoir piston, driven by IPAS air, closes the low level valve. The auxiliary isolation valve, which normally requires two sources of pressure to permit fluid flow, then closes and denies hydraulic power to the AWS turret, external stores actuator, and ammo carrier drive.
Shutoff Valve
A shutoff valve in the pressure line to the directional servo and tail wheel unlock actuator is actuated by the low level switch in the utility system reservoir. The *utility side of the directional servo actuator and the tail wheel unlock actuator become in-operative if a low utility system fluid level is sensed.**
Utility Hydraulic Accumulator
E - Emergency operation of servoactuators
R - Rotor Brake
A - APU Starter motor operation
