Hydraulic Maintenance & Procedures
The required bolt tightening pattern used when installing a hydraulic pump module.
What is a crisscross sequence?
WP 0958, Install (Para 5)
On the hydraulic refill hand pump selector, the reservoir serviced by port number three.
What is the backup pump reservoir?
WP 0025, Refill Handpump and Selector Valve
The maximum allowable fluid leakage rate permitted for any hydraulic pressure switch.
What is 1 drop per day?
WP 0918, Table 1 (Pressure Switches)
The primary flight system that must be completely in rig prior to initiating a tail rotor rig check.
What is the main rotor system?
WP 1203, Inspect (Para 1, Note 1)
The specialized fastener type utilized as the primary structural connection throughout the flight control linkages.
What are self-retaining bolts?
WP 0044, Flight Control Self-Retaining Bolts
The operational time required when bleeding the hydraulic system to ensure all trapped air is expelled.
What is 15 minutes?
WP 0921, Bleed Hydraulic Systems General (Para 3)
The power source that mechanically drives the backup hydraulic pump.
What is an AC electric motor?
WP 0025, Hydraulic Pump Modules (Para 1)
The hydraulic system that supplies operational pressure to stage two of the tail rotor servo.
What is the backup hydraulic system?
WP 0025, Backup Hydraulic System
The maximum allowable distance that the swashplate ball may extend beyond the transmission guide.
What is 0.250 inch?
WP 1201, Service (Para 22, Caution)
The auxiliary component used as an alternate hydraulic power source during pitch travel checks after pitch/trim assembly replacement.
What is the backup hydraulic pump?
WP 1305, Install (Para 13, Caution)
The required torque value, in inch-pounds, applied to the union where the pressure line attaches to a new refill hand pump.
What is 155 to 165 inch-pounds?
WP 0974, Install (Para 4)
The internal component that allows the backup pump to reach rated operating speed before hydraulic load is applied.
What is a depressurization valve?
WP 0025, Hydraulic Pump Modules (Para 6)
The differential pressure range at which the filter bypass pop-up indicator will extend on the hydraulic pump module.
What is 60 to 80 psid?
WP 0025, Hydraulic Pump Module (Para 3)
The primary flight control mechanical subsystem that provides vertical altitude control of the aircraft.
What is the collective control system?
WP 0044, Collective Control System
The prohibited location where self-retaining bolts must never be placed while removing the roll actuator.
What are rod end bearings?
WP 1309, Remove (Para 5, Note)
According to TM 1-1520-280-23&P, this broad maintenance condition triggers a mandatory hydraulic system bleed.
What is replacing any manifolds, tubing, hoses, quick-disconnects, or parts requiring opening the system?
WP 0921, Bleed Hydraulic Systems General (Para 1)
The approved material specified to flush the manifold mating surface prior to installing the No. 1 transfer module.
What is Cleaning Compound, Solvent (WP 2096, Item 94)?
WP 0989, Install (Para 4)
The control axis in which the pitch/trim assembly maintains cyclic stick position.
What is the longitudinal axis?
WP 0026, Pitch/Trim Actuator Assembly
The component replacement criteria that dictate a mandatory main rotor rig check.
What is replacing a main gearbox, rotor head, bellcrank support, swashplate, or flight control component?
WP 1201, Service (Para 1, Note)
The maximum breakout force required to override the slip clutches if a yaw boost actuator jams.
What is 80 pounds maximum?
WP 0098, Trim Subset
The specific internal mating feature on the No. 2 Hydraulic pump module that must never be primed during installation.
What is the packing recess?
WP 0958, Install (Para 3)
The required procedure when building up a replacement hydraulic pump module that is not equipped with new fittings.
What is removing fittings from the old pump or obtaining them from stock?
WP 0958, Module Buildup (Para 1)
The inputs monitored by the hydraulic logic modules to continuously verify system operation.
What are pressure switches, fluid level switches on pump modules, and hydraulic control switches?
WP 0026, Hydraulic Logic Modules
The operational indicator confirming proper control rod adjustment during a main rotor rig check.
What is the long mixer rigging pin installing and removing freely with minimum drag and zero component movement?
WP 1201, Service (Para 18, Note)
The specific tail rotor flight control items whose removal or replacement requires a tail rotor rig check.
What are control cables, cable pulleys, tail rotor blades, and the tail rotor pitch beam?
WP 1203, Inspect (Note 1)