Hydraulics Flashcards
Recall the number of independent hydraulic systems and how they are designated.
• Three independent systems
- Left
- Center
- Right
Recall the purpose of the (ADP) Air Demand Pump and when it activates.
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
Recall the purpose of the HDG (Hydraulic Driven Generator)
• The HDG operates automatically as a backup source of electrical power in the event that both main AC busses become inoperative.
Recall which hydraulic system powers the HDG.
(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
Identify where the reservoir hydraulic quantity is displayed, and the associated indication of the reservoir requiring refilling.
• The EICAS STATUS page –
- The reservoir quantity is displayed in white
- A magenta RF (Refill).is displayed when the reservoir requires refilling (Maintenance action)
Describe the purpose of the RAT (Ram Air Turbine).
• 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.
Identify which hydraulic system powers the high load items
- 757 – Left System
- 767 – Center System
(Memory Aid “Flaps, Slats, Gear, and Steer”)
Recall how the RAT can be deployed.
• 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.
Recall the minimum airspeed to ensure proper RAT operation.
• 130 Knots.
Describe the purpose of the PTU (Power Transfer Unit) and how it can be activated.
• 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.
Explain the meaning of a SYS PRESS (system pressure) light.
System Pressure (SYS PRESS) lights • Illuminated (amber) – the hydraulic system pressure is low.
Recall the meaning of a RSVR (reservoir) light.
Reservoir Low Quantity (RSVR) lights
• B757 Illuminated (amber) –
- Reservoir quantity is low
- Reservoir pressure is low. (Air pressure in the reservoir)
• B767 Illuminated (amber) –
- Reservoir quantity is low.
Recall the ______ electric hydraulic pump may be load shed automatically to reduce electrical loads.
C2
Recall the meaning of the RAT green PRESS light.
Ram Air Turbine Pressure (PRESS) light
Illuminated (green) –
• The RAT is deployed.
• The RAT is producing hydraulic pressure.
Recall the meaning of the RAT UNLKD light.
Ram Air Turbine Unlocked (UNLKD) light
• Illuminated (amber) – the RAT is not stowed and locked.
