UH60M Hydraulic System (FLS) **Need to add LDI***

Question 1

The #1 and #2 hydraulic pumps are driven by ______________________ and supply _____________ hydraulic pressure when the main rotors are turning.

Answer 1

separate transmission accessory gearbox modules

3000 PSI

Question 2

The backup hydraulic pump is powered by a

Answer 2

115 VAC electric motor.

Question 3

If AC power is available, the backup pump is able to provide

Answer 3

hydraulic pressure should one or both hydraulic pumps fail.

Question 4

Each hydraulic pump is a _______ _______, _______ ________ _______.

They maintain the required _________ PSI over ____ ____ of control movement for their own system.

Answer 4

constant pressure, variable volume pump.

3000 PSI
any rate

Question 5

if the #1 and #2 hydraulic pumps are inoperative at the same time, there will be a _______ ________ in the maximum rate of flight control movement. This is due to the backup pump’s inability to provide the __________ _______ because it exceeds the ______ ______ capability of the pumps.

Answer 5

slight restriction
required volume
flow rate

Question 6

Each pump has a _______ and _______ filter.

Answer 6

pressure

return

Question 7

The filters have indicator buttons that extends when the filter is _________.

Answer 7

clogged

Question 8

What happens if the hydraulic pump has a clogged return filter?

Answer 8

the return filter has a bypass capability, allowing hydraulic fluid to return from the system in the event of a filter clog.

Question 9

What if a return filter were to become completely clogged and have no bypass capability?

Answer 9

fluid would be blocked in the return lines causing a hydrostatic flight control lock up.

Question 10

The #1 hydraulic pump supplies hydraulic pressure to the

Answer 10

1(first stage) fore, aft, and lateral primary servos and the #1 tail rotor servo.

Question 11

The #2 hydraulic pump supplies hydraulic pressure to the

Answer 11

2(second stage) fore, aft, and lateral primary servos and the components of the pilot assist area

Question 12

A pressure reducer in the pilot assist module reduces the _____ PSI pump pressure to ______ PSI for use by the ____ ____ servo.

Answer 12

3000 PSI
1000 PSI
pitch trim.

Question 13

The backup hydraulic pump can supply hydraulic pressure to the

Answer 13

1 and/or #2 hydraulic systems independently or simultaneously.

Question 14

The backup hydraulic pump is the only pump that can supply hydraulic pressure to the

Answer 14

2nd stage tail rotor servo and the APU accumulator.

Question 15

The backup pump will come on and provide pressure when any of the following conditions occur:

Answer 15

#1 Reservoir Low (caution light) 
#2 Hydraulic Pump (caution light)
#1 Hydraulic Pump (caution light) 
APU Accumulator Low (advisory light) 
#1 Tail Rotor Servo (caution light)

Question 16

When the SERVO OFF switch is moved to the 1ST STG or 2ND STG position, the primary servos associated with that system are _____ _____.

Answer 16

turned off.

Question 17

When the SERVO OFF switch is moved to 1ST STG, fluid to the #1 forward, aft, and lateral servos are turned off at the _______ ________.

Answer 17

transfer module.

Question 18

A loss of pressure in the #2 primary servos will cause the first stage, turned off but has pressure, to ______ _____ ______ ______ in case the backup system does not take over the function of the failed second stage. If the second stage is initially turned off, the sequence is reversed.

Answer 18

A loss of pressure in the #2 primary servos will cause the first stage, turned off but has pressure, to automatically turn back on in case the backup system does not take over the function of the failed second stage. If the second stage is initially turned off, the sequence is reversed.

Question 19

The leak detection/isolation (LDI) system protects the flight control hydraulic system by

Answer 19

preventing the further loss of hydraulic fluid in case of a leak.

Question 20

The LDI system uses _______ ________ and _______ ______ ______ for monitoring pump hydraulic fluid level, and pump pressure for primary and tail rotor servos, and pilot-assist servos.

Answer 20

pressure switches

fluid level sensors

Question 21

Hydraulic fluid levels may be up to ______ into the ______ ______ (black or blue depending on type of reservoir) when fluid is ____.

Answer 21

3/8”
overfill zone
hot.

Question 22

When the temperature exceeds ______C_/______F_on the label an entry shall be made in the on DA Form 2408-13-1. The aircraft should ___________________________________.

Answer 22

132°C (270°F)

not be flown until appropriate maintenance action has been taken.

Question 23

What is the min pressure required for rotor brake start?

Can I service the rotor brake with the hand pump?

Answer 23

If 450 psi is not attained do not attempt a Rotor Brake start.

Do not service the Rotor Brake with the servicing hand pump, instead contact maintenance for assistance.

Question 24

The hydraulic pump modules on the aircraft consist of a _____________________________________ that is sealed from the atmosphere.

Answer 24

combination hydraulic pump and reservoir

Question 25

A spring in the reservoir maintains a ________ _________ in the system at all times.

Answer 25

positive pressure

Question 26

What controls the operation of the two hydraulic systems?

Answer 26

Two logic modules, one in the left relay panel and the other in the right relay panel, are used to control the operation of the hydraulic systems.

Question 27

The logic modules continually monitor the operation of the hydraulic systems by inputs received from ________ _______, _______ ______ ______ on the pump modules, and inputs received from control switches in the hydraulic system.

Answer 27

The logic modules continually monitor the operation of the hydraulic systems by inputs received from pressure switches, fluid level switches on the pump modules, and inputs received from control switches in the hydraulic system.

Question 28

The outputs of the ______ _______ will either activate cautions/advisories notifying the pilot of a failure and/or turn off one or more valves due to a system malfunction.

Answer 28

logic modules

Question 29

Components of the Pilot Assist Area receiving hydraulic power from the #2 Hydraulic Pump are:

Answer 29

pitch, roll, and yaw SAS actuators, pitch boost servo, collective and yaw boost servos, and the pitch trim assembly.

Question 30

At what PSID will the Hydraulic pumps' filter indicator buttons pop?

Answer 30

70 PSID, plus or minus 10

Question 31

At what PSID will the return filter bypass activate?

Answer 31

100 PSID, plus or minus 10

Question 32

What piece isolates the primary servos, and where is it located?

Answer 32

the primary shutoff valve, located on the transfer modules after moving the SERVO OFF switch to 1ST STG or 2ND STG.

Question 33

If one set of primary servos (#1 or #2) is to be isolated, the other primary servo set must be pressurized to at least ________?

Answer 33

2350 psi

Question 34

A leak in the pilot's assist module will cause the following caution lights to illuminate:_____________, _____________, ____________,______________, and ______________ .

Answer 34

``` No. 2 RSVR LOW BOOST SERVO OFF SAS OFF TRIM FAIL FLT PATH STAB ```

Question 35

The UH-60 is limited to a ______bank angle when a PRI SERVO PRESS caution light is on.

Answer 35

30 degree

Question 36

A 1.5-gpm (a)______________ will automatically shut off hydraulic pressure from the backup pump to the accumulator if a (b)______ increase in flow rate (when above 1.0 gpm) or (c)_______ drop in pressure across the velocity fuse occurs.

Answer 36

(a) velocity fuse (b) .5-gpm (c) 30-psi

Question 37

In the event both tail rotor cables break, a (a)_____________ places the pilot valve in a position that gives a positive pitch of (b)_______ degrees in the tail rotor.

Answer 37

(a) centering spring | (b) 10.5

Question 38

This toggle switch is used to test the complete leak isolation system with the exception of the low-level switches and velocity fuse.

Answer 38

** check answer ** | LDI test switch

Question 39

The __________________ directs the flow of hydraulic pressure from the backup pump to the No. 1 or No. 2 transfer module or second stage tail rotor and APU accumulator. It is attached to the side of the pump module

Answer 39

Utility Module

Question 40

The two ___________________ are an integrated assembly of restrictors, switches, and valves which connect hydraulic pressure from the pump to the servos and provide automatic switching to the backup pump in case the No. 1 or No. 2 system fails.

Answer 40

Transfer Modules

Question 41

The accumulator, located on the rear cabin ceiling, holds a nitrogen charge of (a)_______ psi and a hydraulic charge of (b)________ psi (+/- 150).

Answer 41

(a) 1,450 | (b) 2,850

Question 42

A pressure drop below (a)________ psi will cause the NO. 1 HYD PUMP or NO. 2 HYD PUMP caution light to come on. At this time, the (b)____________ will shuttle and allow the backup pump to come on line and supply hydraulic pressure to either system.

Answer 42

(a) 2000 | (b) transfer valve

Question 43

How does LDI know when a leak is present?

Answer 43

LDI uses pressure switches and fluid level sensors for monitoring pump fluid levels for primary servos, tail rotor servos and pilot assist servos.

Question 44

What is the function of the logic module?

Answer 44

When a pump module or reservoir fluid level detects fluid loss, the logic module follows a sequence to isolate the leak.