Hydraulics Flashcards
How many independent hydraulic systems are there, and how are they designated?
Three: Left, Center, Right
What is the purpose of the Air Demand Pump (ADP) and how does it operate?
ON- Continuous operation
AUTO- center ADP operates when both center electric pump pressures are low, or when heavy load items are selected
OFF- pump off.
What is the purpose of the Hydraulic Driven Generator (HDG)?
Operates automatically as a backup source of electrical power in the event that both main AC buses become inoperative.
On the 767ER, which system powers the HDG?
Center hydraulic system powers the HCG using the Air Demand Pump (ADP)
On the 757-300, which system powers the HDG?
Left hydraulic system powers the HDG using left hydraulics or PTU.
Where is hydraulic fluid quantity displayed, and what is the indicator of low quantity?
EICAS status page, low quantity indicated by magenta RF (refill).
What is the purpose of the Ram Air Turbine (RAT)?
To provide flight control operation- RAT deploys automatically when both engines fail and provides hydraulic pressure to the flight controls using the center hydraulic system.
Which hydraulic system powers the high load items?(Flaps, Slats, Gear, and Steer)
757- Left system
767- Center system
How can the Ram Air Turbine be deployed?
Automatically when both engines fail, RAT is inhibited from auto deploying on the ground.
Manually by pushing the RAM AIR TURB switch.
Caution: Can be manually deployed on the ground.
What’s the minimum airspeed to ensure proper RAT operation?
130 kts
What is the purpose of the Power Transfer Unit (PTU), and how is it activated?
Hydraulic motor pump which transfers hydraulic power from the right system to the left. The PTU is automatically activated if the left engine fails and the right engine is operating, or the left engine-driven pump pressure is low with the right engine operating.
What does an amber illuminated SYS PRESS light indicate?
System pressure is low.
What does an amber illuminated RSVR light indicate?
757- Reservoir quantity is low, or reservoir pressure is low.
767- Reservoir quantity is low
Can the center hydraulic pumps be load shed?
Only Center #2 may be load shed automatically to reduce electrical loads.
What does the RAT green PRESS light mean?
- RAT is deployed
- RAT is producing hydraulic pressure
