7ER Hydraulics Flashcards
(41 cards)
How many hydraulic systems are there, and how are they designated?
Three systems
Designated as Left, Center, Right
What is the purpose of the Air Demand Pump, and when does it operate?
When its selector is in AUTO, the ADP operates to pressurize the Center system when heavy load items are selected, when both electric pump output pressures are low, or when the left center (C1) pump is isolated.
When its selector is in ON, the ADP runs continuously
How is the ADP powered?
Bleed air from the center portion of the bleed manifold (Center isolation valve must be open or APU bleed must be on)
What is the purpose of the Hydraulic Driven Generator?
Operates automatically in the event of a loss of both main AC busses, uses hydraulic pressure to provide backup electrical power
Which hydraulic system powers the HDG?
757: Left system via the Left engine pump or PTU
767: Center system. The ADP will operate continuously so long as its selector is in AUTO
Where is the hydraulic reservoir quantity indication located?
On the EICAS STATUS page
What is the indication that a hydraulic reservoir requires refilling?
A magenta RF next to the quantity on the EICAS STATUS page
What event will automatically deploy the RAT?
A failure of both engines in flight?
Can the RAT be deployed on the ground
Yes, but only manually
How can you manually deploy the RAT?
Press the RAM AIR TURB switch on the Center Overhead
What are the indications in the RAM AIR TURB switch, and what do they mean?
UNLKD (amber): the RAT is not stowed and locked
PRESS (green): the RAT is deployed and is producing hydraulic pressure
What does the RAT power?
The primary flight controls via the Center hydraulic system
Which hydraulic system powers the high load items (Flaps, slats, landing gear, nosewheel steering)?
757: the Left system, with backup from the PTU
767: the Center system, with backup from the ADP (these cannot be powered by the RAT)
What is the minumum airspeed for proper operation of the RAT?
130 knots
What is the purpose of the PTU, and how is it activated?
The PTU transfers power from the Right system to the Left system
It operates automatically when the right engine is operating and:
The left engine fails -OR- the left engine-driven pump output pressure is low
(the PTU is only on the 757)
What is the meaning of a SYS PRESS light?
The respective system pressure is low
Accompanied by an EICAS caution SYS PRESS
What is the meaning of a RSVR light?
757: the respective reservoir pressure is low (HYD RSVR PRESS advisory) or reservoir quantity is low (HYD QTY advisory)
767: the respective reservoir quantity is low (HYD QTY advisory)
How are the hydraulic reservoirs pressurized?
By the bleed air system
When is the C2 hyd pump shed to reduce electrical loads?
When all electric hyd pumps are on, and only APU or External power is vailable
What is the meaning of any HYD PUMPS PRESS light?
The respective pump output pressure is low
(757: HYD ELEC PUMP, HYD ENG PUMP, or HYD ELEC 1(2) advisories)
(767: L(R) HYD DEM PUMP, L(R) HYD PRIM PUMP, or HYD PRIM 1(2) advisories)
What is the meaning of any HYD PUMPS OVHT light?
The respective pump temperature is high
757: ELEC HYD OVHT, ENG HYD OVHT, or C HYD 1(2) OVHT advisories
767: DEM HYD OVHT, PRIM HYD OVHT, or C HYD 1(2) OVHT advisories
What is the function of the hydraulic demand pump selectors?
OFF - the pump is off
AUTO (left or right pump) - the pump operates when the engine pump pressure is low
AUTO (center pump) - the pump operates when both center electric pump pressures are low or if heavy load items are selected
ON - the pumps are on
(767) What is the meaning of a left demand pump PRESS or SYS PRESS light during engine start?
Normal indication due to load shedding of the demand pump during start of either engine when only one generator is operating
(767) What does it mean if the Center SYS PRESS light remains illuminated when the RAT is deployed?
The RAT is the only source of Center system pressure, and it is only powering the flight controls
