Hydraulics - Question Bank

Question 1

When will the demand pumps operate if the hydraulic demand pump selector is in the AUTO position?

Answer 1

• Demand pumps operate when related engine pump output pressure is low
• Demand pumps 1 & 4 also operate when flaps are in transit, or flaps extended past 1
-When respective fuel control switch is in CUTOFF

Question 2

What does the hydraulic system (SYS FAULT) fault light indicate?

Answer 2

• Low hydraulic system pressure
• Low hydraulic reservoir quantity
• Excessive hydraulic fluid temperature

Question 3

What does a hydraulic demand pump low PRESS light indicate?

Answer 3

• Demand pump selector positioned to OFF or AUX

* Demand pump commanded to operate and output pressure is low

Question 4

What does a hydraulic reservoir quantity indication of .80 mean, as displayed on the Secondary EICAS display?

Answer 4

80% of normal service level

Question 5

What does a magenta “RF” displayed next to a hydraulic quantity indicator on the Secondary EICAS mean?

Answer 5

The reservoir requires refill

Question 6

When is the engine driven hydraulic pump pressurized?

Answer 6

• The engine is running

* The engine pump switch is ON

Question 7

Which demand pumps are air driven, and which ones are electric motor driven?

Answer 7

• Systems 1 and 4 are air driven pumps, through the bleed air manifold.
• Systems 2 and 3 are electric driven pumps.

Question 8

What is the purpose of the auxiliary pump?

Answer 8

Used for ground handling operations

Question 9

Why are the hydraulic reservoirs pressurized by the bleed air system?

Answer 9

• To prevent pump cavitation

* To ensure positive flow during high demand conditions

Question 10

How does pulling a fire switch affect the hydraulic system?

Answer 10

• Respective hydraulic fluid shutoff valve closes.
• The EDP depressurizes.
• The respective demand pump operates.

Question 11

What are some examples of major system components powered by each hydraulic system?

Answer 11

• Systems 1 and 4 power the trailing edge flaps, body gear, normal brakes
(SYS 4), alternate brakes (SYS 1), and steering. Systems 1 and 4 also
provide redundant power to the primary flight controls.
• Systems 2 and 3 power the primary flight controls, stabilizer trim, and
elevator feel. System 2 also powers the alternate brakes and lower yaw
damper. System 3 powers the upper yaw damper.
• Systems 1, 2, and 3 power the respective center, right, and left autopilot
servos (L,C,R are powered by systems 3,1,2 respectively)
• Systems 2, 3, and 4 power the spoilers.