Hydraulic Systems

Question 1

The ____________ reduces the mechanical workload of the Pilot in the manipulation of the flight controls.

Answer 1

hydraulic system

Question 2

Small movements of the flight controls direct hydraulic fluid at a pressure of _______ to the proper side of the power cylinder, causing the desired movement in the rotors.

Answer 2

1,000 psi

Question 3

A power cylinder for the tail rotor control operates similarly to those for the collective and cyclic, but consists of only 1 sec powered by System __.

Answer 3

1

Question 4

Hydraulic systems are comprised of 6 basic elements:

Answer 4

Fluid
Reservior
Pump
Pressure Control
Fluid Control
Actuators

Question 5

Incompressible and flexible. Can transmit force in any direction. Resists chemical breakdown, is non-corrosive, and provides cooling and lubrication for system components.

Answer 5

Fluid

Question 6

Storage for a reserve supply of fluid to compensate for leakage. Allows for thermal expansion of fluid.

Answer 6

Reservior

Question 7

Ensures the proper amount of fluid is available at the appropriate pressure. May be electrically or mechanically powered.

Answer 7

Pump

Question 8

May be accomplished by pressure regulator valve(s) or pressure relief valve(s).

Answer 8

Pressure Control

Question 9

Permit flow in 1 direction only.

Answer 9

Check valves

Question 10

Protect system integrity in the event of excessive fluid temperature.

Answer 10

Thermal relief valves

Question 11

Transform the energy of fluid flow to mechanical force.

Answer 11

Actuators

Question 12

UH-1N main rotor cyclic and collective controls are powered by 2 separate and completely independent hydraulic systems, referred to as ______ and _______.

Answer 12

System 1/System 2

Question 13

System 1 and 2 reservoirs are identical, _________ units which hold approximately _____ of hydraulic fluid.

Answer 13

• non-pressurized

- 2.5 qt

Question 14

Pumps are identical in function, but operate at different speeds (due to their location on the transmission). #1: ________; #2: __________.

Answer 14

1: 4,300 rpm
2: 6,600 rpm

Question 15

Hydraulic pumps are rated at _______

Answer 15

1,000 psi (± 25)

Question 16

Hydraulic Pumps: ______ minimum delivery rate at normal operating rpm.

Answer 16

6.0 gpm

Question 17

When the solenoid valve is closed (i.e., at aircraft shut down or if an individual system is deselected during flight), the _______ and/or _________ caution segment will illuminate as the system pressure drops below ____ psi.

Answer 17

• HYD SYS 1 and HYD SYS 2

- 650

Question 18

Integrated Valve and Filter Assembly: Relief valve - will relieve hydraulic overpressure in __________ psi range.

Answer 18

1,100 - 1,300

Question 19

Integrated Valve and Filter Assembly: ____________ - activates cockpit caution light when pressure drops below ____ psi

Answer 19

• Pressure switch

- 650

Question 20

Integrated Valve and Filter Assembly:

____________ system shutoff valve:

1) Electrically held closed and depowered open for fail safe operation.
2) Takes electrical power to turn the system off.

Answer 20

Solenoid operated

Question 21

Integrated Valve and Filter Assembly:

____________ shutoff valve:

1) Automatically shuts system down if pressure drops to 600 psi or below.
2) Preserves remaining hydraulic fluid in servos.
3) Automatically opens when system pressure is at or above ____ psi.

Answer 21

• Pressure operated

- 750

Question 22

Integrated Valve and Filter Assembly:

There are __ filters for each system.

Answer 22

2; 1 for pressure and 1 for return fluid flow.

Question 23

Integrated Valve and Filter Assembly:

They filter particles down to ___ microns.

Answer 23

5

Question 24

Integrated Valve and Filter Assembly:

Non-electric pop-out indicators for each filter:

a) Red indicators pop at ___ psi pressure differential across filter element.
b) An electrical circuit trips a cloverleaf type indicator in the Pilot’s chin window; the indicator turns white when any of the __ filters is clogged.
c) To determine which filter is clogged, the indicators on the valve and filter assembly must be _______ checked.

Answer 24

• 70
• 4
• visually

Question 25

__________ are cylinders incorporating a spring loaded piston.

Answer 25

Accumulators

Question 26

Where is the electrically operated clogged filter indicator for the hydraulic systems located?

Answer 26

Nose compartment seen through the Pilot’s chin window.

Question 27

The pressure operated shutoff valve closes at __________ psi in order to isolate an inoperative hydraulic system.

Answer 27

600

Question 28

The appropriate HYD SYS caution panel segment will illuminate when the pressure drops below __________ psi and extinguish when pressure rises above __________ psi.

Answer 28

650; 750

Question 29

T/F: In the event of a dual hydraulic system failure, an airspeed of approximately 70 kts will normally provide the least amount of feedback in the flight control system.

Answer 29

True