HYD System Flashcards
NATOPS Chap 2
Hydrualic System
What Components do the Hyd pumps provide Pressure to?
Flight controls, APU, Tail Rotor, Resucue Hoist.
NATOPS Chap 2
Hydrualic System
The Hydraulic System Components are?
Three identical and interchangeable Pumps, Two transfer mods, one util mod, three dual-stage primary servos, tail rotor servos, pilot-assist servos, apu accum, and rescue hoist.
NATOPS Chap 2
Hydrualic System
What are the only actuators that don’t operate at 3000psi?
Pitch and roll trim actuators
NATOPS Chap 2
Hydrualic System
Can the systems operate idependently of each other?
Yes they can, but they are also redundant and supported by the electric motor-driven backup pump
NATOPS Chap 2
Hydrualic System
What drives the #1 hyd pump?
The #1 access mod
NATOPS Chap 2
Hydrualic System
What is incorporated into the Hydraulic pump?
a Pressure relief valve, pressure filter, bleed valve, return filter, auto low-level sensing switch
NATOPS Chap 2
Hydrualic System
What triggers the RSV Low Caution?
The automatic low-level sensing switch (mounted on top of the pump)
NATOPS Chap 2
Hydrualic System
What does the Priority Valve do?
It will secure Pressure to the Rescue hoist if the Backup pump is supplying pressure to the tail rotor servo
NATOPS Chap 2
Hydrualic System
How long does it take to for the B/U pump to energize?
4sec on APU/ext pwr or 0.5sec with either main gen on.
NATOPS Chap 2
Hydrualic System
On/Auto/off fx of B/U pump (WOW activated)
OFF- B/U pump remains off
Auto- B/U auto maintains px for #1/2 Hyd Pump and #2 TR servo
On- B/U pump recirculates hyd fluid to and from each xsfr mod and maintains Px in APU accum and rescue hoist as rq’d
NATOPS Chap 2
Hydrualic System
What causes the Backup Pump to automatically turn on?
#1 HYD Pump Caution #2 HYD PUMP Caution #1 RES LOW Caution #1 TR Caution
NATOPS Chap 2
Hydrualic System
What Criteria must be met to run Hyd Leak Test? (ABWAR)
1) AC power
2) B/U Pump in AUTO position
3) WOW
4) All Hyd Resv Full
5) Rotors Engaged
NATOPS Chap 2
Hydrualic System
Collective to yaw
Name: Collective to Yaw
Cause: Main Rotor Torque
Compensation Requirement: Nose yaws right when collective is increased
Compensation: Tail rotor thrust is increased
NATOPS Chap 2
Hydrualic System
Collect to Lateral
Name: Collective to Lateral
Cause: Lateral Lead (tail rotor propeller effect)
Compensation Requirement: Helo drifts right when collective is increased.
Compensation: Rotor disc is tilted left
NATOPS Chap 2
Hydrualic System
Collect to Long
Name: Collective to Longitudinal
Cause: Rotor downwash on stabilator
Compensation Requirement: Nose pitches up and helicopter drifts aft when collective is increased
Compensation: Rotor disc is tilted forward
NATOPS Chap 2
Hydrualic System
Yaw to Long
Name: Yaw to Longitudinal
Cause: Tail Rotor lift vector
Compensation Requirement: Nose pitches down and helicopter drifts forward when left pedal is applied.
Compensation: Rotor disc is tiled aft
NATOPS Chap 2
Hydrualic System
Collect/airspeed to yaw
Name: Collective/Airspeed to Yaw
Cause: Camber of tail rotor pylon varies side load with airspeed
Compensation Requirement: Nose yaws left as airspeed increases
Compensation: A portion of the main rotor torque compensation is provided by a trim input that is proportional to collective position and airspeed. The trim input is then progressively washed out as pylon side loads increase with airspeed.
NATOPS Chap 2
Hydrualic System
What is the job of the Transfer Module?
It automatically routes hydraulic fluid from the backup pump if No. 1/2 Hydraulic system pressure is lost.
NATOPS Chap 2
Hydrualic System
What are the components in the #1 Transfer Module
It consists of:
a transfer/shuttle valve,
pressure switch,
first-stage primary servo shutoff valve,
and first-stage tail rotor servo shutoff valve.
*The #2 is the identical except it incorportates the second stage Primary servos
NATOPS Chap 2
Hydrualic System
What happens if No. 1 Hydraulic pressure is lost?
The transfer/shuttle valve routes backup pump hydraulic fluid to the first stage of the primary servos and the first stage of the tail rotor servo. The pressure switch illuminates the #1 HYD PUMP caution and sends a signal to the LDI when No. 1 hydraulic pump pressure drops below prescribed limits.
NATOPS Chap 2
Hydrualic System
What causes the PRI SERVO PRESS caution?
When at least one of the three pressure switches on the first or second stage of the primary servos sense low hydraulic pressure, a circuit is completed that actuates the #1/#2 PRI SERVO PRESS caution
NATOPS Chap 2
Hydrualic System
What switches and valves are on the Transfer Module, and what are the associated cautions/advisories?
1) Pressure Switch- #1/#2 HYD PUMP
2) Transfer Valve- no associated caution/advisory
3) Shutoff Valves-
a) 1st stage Pri servo shutoff valve
b) 1st stage Tail Rotor shutoff valve
c) Pilot assist servo assembly shutoff valve
d) 2nd stage Pri servo shutoff valve
