Hydraulic System Flashcards

0
Q

Where can hydraulic quantity and pressure be monitored?

A

Can be monitored on STATUS display or hydraulic synoptic display.

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1
Q

After engine start, under what circumstances would you expect the left or right demand pumps to run?

A
  • System low pressure
  • On the ground, 3 minutes after second engine start
  • Takeoff thrust set to flaps retracted
  • From gear down or RA less than 1000’ to GS less than 40kts
  • During thrust reverser operations
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2
Q

After engine start, under what circumstances would you expect the center demand pump to run?

A
  • System low pressure
  • On the ground, 3 minutes after second engine start
  • Takeoff thrust set to RA >2000’
  • From gear down and RA less than 2000’ to GS less than 60kts
  • Flaps or slats in motion
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3
Q

Why does the center system have an isolation feature?

A

To preserve system functionality in the event of a leak, allowing crew to be able to lower landing gear and have nose gear steering on landing roll.

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4
Q

When does the RAT deploy automatically?

A
  • Both engines have failed
  • All three hydraulic system pressures are low
  • Loss of all electrical power to the CPT & FO flight instruments
  • Loss of all 4 EMP’s and faults in the flight control system occur on approach.
  • Loss of all 4 EMP’s and an engine fails on takeoff or landing.
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5
Q

When will a hydraulic pump FAULT light illuminate?

A
  • Low primary pump pressure
  • Excessive pump fluid temperature
  • Pump is selected off
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6
Q

Will a hydraulic pump shutdown/stopped by system logic (i.e. Before engine start etc) cause the FAULT light to illuminate?

A

No. A pump manually selected OFF will illuminate the FAULT light.

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7
Q

With the C1 demand pump switch selected on, when will the pump run?

A

Continuously

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8
Q

Which systems are powered by the center hydraulic system?

A
  • Flaps/Slats
  • Landing gear actuation
  • Nose wheel steering
  • Flight controls
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9
Q

Which systems are powered by the Left and Right hydraulic systems?

A

Flight controls and the respective side thrust reverser

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10
Q

Will the OF and RF indications show in the air?

A

No, only on the ground

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11
Q

Below what value will the hydraulic pressure display in amber in the synoptic display?

A

Below 3000psi

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12
Q

When does the RAT “PRESS” light illuminate?

A

When the system pressure for the flight controls is higher than 3000psi

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13
Q

What determines which Center pump will be primary and which will be demand?

A

Day of the week from the FMC

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14
Q

Below what pressure is an EMP displayed in amber as failed on the synoptic display? EDP?

A

EMP - amber below 2000psi

EDP - amber below 2150psi

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15
Q

Which hydraulic systems have an isolation functionality?

A

Center system only

16
Q

What is the purpose of the accumulators in the hydraulic systems?

A
  • Absorb pressure changes during operation

- Keep positive bootstrap pressure in system when pumps do not operate. This prevents pump cavitation on startup.

17
Q

How are the hydraulic systems cooled?

A

By heat exchangers in the main fuel tanks.

Each system has one heat exchanger in its respective tank, Center system has one heat exchanger in each tank.

18
Q

What is the purpose of the reservoir suction shutoff valve in the left and right systems?

A
  • Ensures system doesn’t lose all hydraulic fluid if there is a leak in the tubing to the EDP.
  • Fluid will be shut off to EDP ensuring EMP has enough remaining in the tubing to operate flight controls.
19
Q

What is the purpose of the reservoir suction shutoff valve in the center system?

A
  • Ensures system doesn’t lose all hydraulic fluid if there is a leak in the tubing to the EMP C2. (MLG and flight controls)
  • Fluid will be shut off to EMP C2 ensuring EMP C1 has enough remaining in the tubing to operate nose wheel steering and flaps.