Utility Module

Question 1

Location

Answer 1

Fwd hydraulic compartment, lower left side on the deck aft

Question 2

Purpose

Answer 2

Filters and distributes both pressure and return fluid for the utility hydraulic system

Question 3

Check valves

Answer 3

One prevents the pump from turning into a motor when external hydraulic power is connected

Other prevents the QD on the servicing panel from leaking when system is operating minus the cup

Question 4

Snubber

Answer 4

Reduces pressure oscillations at gauge

Question 5

Relief valves

Answer 5

Utility system relief valve- Opens at 3500 psi

Engine start replenishment relief valve- opens at 2500 psi

Question 6

Pressure reducers

Answer 6

AFCS “servo 2”-1000 psi
Wheel breaks-1500 psi
Engine start replenishment - 80 psi

Question 7

Priority valve

Answer 7

Restricts the use of all utility hydraulic subsystems
Closes at below 2000 psi
Opens at above 2100 psi

Question 8

Isolation valve

Answer 8

Restricts use of non-essential hydraulic subsystems while jn flight
Normally closed, energized open
Energized on the ground by right MLG switch
Energized in flight by operating any utility subsystem electrically

Question 9

Pressure switches

Answer 9

Tail rotor servo 2000 psi, lights “utility T/R press” when below 2000 psi

AFCS “servo 2” 2000 ps, above 200psi lights “servo 2” on AFCS control panel below 2000 psi auto transfers to servo 1

Question 10

Isolation check valve

Answer 10

Prevent utility return fluid from back flowing to the subsystems when the isolation valve is closed

Question 11

Tail rotor shut-off switch

Answer 11

Spring loaded open, energized closed
Secures pressure to the utility hydraulic supplied side of the tail rotor servo

Question 12

AFCS Servo 2 turn-on valve

Answer 12

Spring loaded closed, energized open
Allows pressure to operate the utility hydraulic supplied side of the AFCS servos

Question 13

Engine Start control Valve

Answer 13

Control utility pressure to the engine start system
Spring loaded closed, energized open
Controlled by 3 start buttons on the speed controller levers

Question 14

Landing gear control valve

Answer 14

Directs pressure to operate the landing gear
Controlled by pressure via the up and down solenoids
The VP line is open to return in the neutral position to prevent thermal expansion from retracting the landing gear

Question 15

Emergency bypass valve

Answer 15

Nitrogen operated, manually closed
Opened by discharging nitrogen from landing gear-down bottle
By passes normal return preventing a hydraulic lock, allowing the landing gear to extend

Question 16

Return filter

Answer 16

Same as others