Study Guide: Hydraulics Flashcards
757: The power transfer unit (PTU) is automatically activated:
If the left engine fails or the left engine-driven pump pressure is low
757: The hydraulic motor generator (HMG) is automatically powered by the
___________ whenever both main AC busses become unpowered in flight.
The left engine hydraulic pump or the PTU, if operating
767: The hydraulic motor generator (HMG) is automatically powered by the
___________ when electrical power is lost from both main AC busses.
The center hydraulic system
757/767: When deployed, the RAT drives a hydraulic pump that supplies adequate
pressure for flight controls down to an airspeed of approximately ______.
130 knots
757: The center hydraulic system reservoir contains a standpipe to reserve hydraulic
fluid for the ________ in the event of a center system hydraulic leak.
Ram air turbine (RAT)
757: To prevent electrical overloads, the No. 2 electric pump is inhibited when only one generator (APU or engine) or only external power is available and:
Both center hydraulic electric pump switches are on
757/767: According to the graphic, what is the status of the ram air turbine (RAT)?
The RAT is not stowed and locked, and is producing hydraulic pressure
757: External power is the sole source of electrical power. The center No. 2 electric hydraulic primary pump PRESS light is illuminated because:
In order to prevent electrical overloads, the pump is inhibited
757/767: The hydraulic quantity for each hydraulic system is displayed:
On the EICAS status display
757: According to the graphic, the RSVR light is illuminated. This indicates that:
Reservoir quantity is low (below 50%) or reservoir air pressure is low
757: According to the graphic, the EICAS POWER XFER UNIT status message is displayed. What is the status of the power transfer unit (PTU)?
The PTU is not operating properly
757: Trailing edge flaps and leading edge slats are hydraulically operated by drive units normally powered by the _____ hydraulic system(s).
Left
757/767: Yaw control is provided by a single rudder which receives hydraulic power from
the _________ hydraulic system(s).
Left, center, and right
757: According to the graphic, when the RESERVE BRAKES switch is activated, fluid trapped below a standpipe is made available to the _________ system electric hydraulic pump.
Right
757: When activated, the power transfer unit (PTU) supplements the left hydraulic system electric motor-driven pump to operate the following:
Flaps and slats, landing gear, nose wheel steering, HMG
767: Across the entire aircraft, how many hydraulic reservoir standpipes are there?
One
757: Across the entire aircraft, how many hydraulic reservoir standpipes are there?
Three
767: The center system reservoir contains a standpipe to reserve a supply of fluid for the:
Reserve brakes and steering system
767: To prevent electrical overload, the No. 2 electric primary pump is inhibited when
only one generator (APU or engine) or only external power is available and _________ is/are commanded to operate.
The other three electric hydraulic pumps
757/767: The _________ is available to supply hydraulic pressure to the center system
flight controls in the event of a dual engine failure in flight.
Ram air turbine (RAT)
767: When the RESERVE BKS & STRG switch is pressed, the ____________ is turned
on regardless of switch position.
Center system No. 1 electric primary pump
757/767: The ram air turbine (RAT) is armed:
On the ground above 80 knots
767: In the AUTO position, the air-driven demand pump (ADP) operates automatically whenever the landing gear, flaps, slats, or speed brakes/ground spoilers are selected for operation. The ADP will also operate when:
Center system hydraulic pressure drops to a preset value
757: When the hydraulic motor generator (HMG) is operating, hydraulic flow to the flaps
and slats is _______, resulting in:
Reduced, increased operating time for these items
757: Can the hydraulic motor generator (HMG) be driven by the power transfer unit (PTU)?
Yes, the HMG may be driven by the PTU, if operating
767: When the air-driven pump (ADP) is inoperative:
Landing gear retraction and flap extension/retraction times increase
