Hyrdraulics

Question 1

Recall the number of independent hydraulic systems and how they are designated

Answer 1

• Three independent systems
• Left
• Center
• Righ

Question 2

Recall the purpose of the (ADP) Air Demand Pump and
when it activates

Answer 2

Center Air Demand Pump selector

• AUTO –
• The ADP operates when heavy load items are selected.
• The ADP operates when both center electric pump
  output pressures are low (The Center system pressure is low)
• ON – The ADP operates continuously

Question 3

Recall the purpose of the HDG (Hydraulic Driven Generator)

Answer 3

• The HDG operates automatically as a backup source of electrical power in the event that both main AC busses become inoperative.

Question 4

Recall which hydraulic system powers the HDG.

Answer 4

• (757 as installed) The Left hydraulic system powers the
  HDG using the Left engine driven pump or the PTU.
• (767 as installed) The Center hydraulic system powers the
  HDG using the ADP

Question 5

Identify where the reservoir hydraulic quantity
is displayed, and the associated indication of the reservoir requiring refilling.

Answer 5

• The EICAS STATUS page –
• The reservoir quantity is displayed in white
• A magenta RF (Refill).is displayed when the reservoir
  requires refilling (Maintenance action)

Question 6

Describe the purpose of the RAT (Ram Air Turbine).

Answer 6

• The RAT, when deployed, provides hydraulic power to the
  flight controls portion of the center hydraulic system.

Note: The RAT deploys automatically when both engines fail.

Question 7

Identify which hydraulic system powers the high load
items (Memory Aid “Flaps, Slats, Gear, and Steer”)

Answer 7

• 757 – Left System
• 767 – Center System

Question 8

Recall how the RAT can be deployed.

Answer 8

• In flight, the RAT deploys automatically when both engines fail

Note: The RAT is inhibited from Auto deployment on the ground

• Manually by pushing the RAM AIR TURB switch

CAUTION: The RAT can be Manually deployed on the ground.

Question 9

Recall the minimum airspeed to ensure proper RAT
operation.

Answer 9

• 130 Knots.

Question 10

Describe the purpose of the PTU (Power Transfer Unit)
and how it can be activated

Answer 10

• The PTU is a hydraulic motor pump which transfers
  hydraulic power from the right system to the left system.
• The PTU is automatically activated:
• If the left engine fails and the right engine is operating
• If the left engine-driven pump pressure is low and the
  right engine is operating

Question 11

Explain the meaning of a SYS PRESS (system
pressure) light

Answer 11

• Illuminated (amber) – the hydraulic system pressure is low.

Question 12

Recall the meaning of a RSVR (reservoir) light.

Answer 12

• B757 Illuminated (amber) –
• Reservoir quantity is low
• Reservoir pressure is low. (Air pressure in the reservoir)
• B767 Illuminated (amber) –
• Reservoir quantity is low.

Question 13

Recall the C2 electric hydraulic pump may be load shed
automatically to reduce electrical loads.

Question 14

Recall the meaning of the RAT green PRESS light.

Answer 14

Illuminated (green) –
* The RAT is deployed.
* The RAT is producing hydraulic pressure.

Question 15

Recall the meaning of the RAT UNLKD light.

Answer 15

• Illuminated (amber) – the RAT is not stowed and locked.

Question 16

Recall the meaning of any HYD PUMPS press light.

Answer 16

• Illuminated (amber) – the pump output pressure is low

Question 17

Recall the meaning of any OVHT HYD PUMPS light.

Answer 17

• Illuminated (amber) – the pump temperature is high

Question 18

Recall the operation of the hydraulic demand pump
selectors.

Answer 18

Left / Right Electric and Center Air (L/R ELEC and C AIR)
Demand Pump selectors

• OFF – The pump off
• ON – The pump will operate continuously
• AUTO –
• The left / right electric pumps operate when the engine
  pump pressure is low
• The center air demand pump operates when both center electric pump pressures are low or heavy load
  items are selected