HYDRAULICS

Question 1

Explain the function of the AUX hydraulic pump switch:

Answer 1

The auxiliary pump, an electric motor-driven pump, has two functions:
as a backup to the right engine-driven pump, and to pressurize the
hydraulic systems on the ground when the engines are not running.
 The electrically driven auxiliary pump is a crew-selectable backup for
the right hydraulic system and powered by the left generator bus.
 If the right engine-driven pump fails, or the right engine fails, the
auxiliary pump may be used to supply pressure to operate all right
system components, including the landing gear.
 The auxiliary pump has built-in thermal protection and automatically
shuts down if it overheats
 ON – Turns on electrical hydraulic auxiliary pump.
 OFF – Turns off electrical hydraulic auxiliary pump

Question 2

Recall the function of the hydraulic transfer pump switch:

Answer 2

The transfer pump enables a pressurized system to mechanically
transfer power to an unpressurized system when both systems
reservoir quantities are normal.
 OFF - Closes valve on each side of Power Transfer Unit (PTU) to
disconnect left and right systems.
 ON - Opens valve on each side of PTU to connect left and right
systems. Automatically allows the system with low pressure to be
pressurized by the system with normal pressure in the event one
system loses pressure.

Question 3

Recall how to determine if hydraulic quantities are adequate both before
and after engine start:

Answer 3

The reservoirs are displayed as rectangular boxes on the synoptic.
Reservoir quantity is displayed by shading in each rectangle and
numerical readouts below each rectangle.
 Each reservoir has a fixed quantity reference line. The reference line
appears after engine start when each engine reaches idle.
 Hydraulic digital quantity
White - Fluid level within limits.
Amber - (Values boxed) Fluid levels below limits.
 Pre-Flight Hydraulic Fluid Level – cyan
Cyan - Normal.

Question 4

Recall that the engine driven hydraulic pumps operate during electrical
failure:

Answer 4

When the engines are running and the pump switches are ON, the
pumps supply 3000psi pressure to their respective hydraulic system.
 When electrical power is removed from an engine-driven pump, the
pump defaults to on. When the switch is moved to the OFF position, the
pump is electrically commanded to zero pressure output

Question 5

Recall the indications of normal and non-normal hydraulic pressures:

Answer 5

When pump output pressure drops below a predetermined value the
letter P is displayed next to the respective pump symbol on the
synoptic. Hydraulic system pressure readouts are digitally displayed on
the synoptic.
Hydraulic Pressures:
 White - Pressure within limits.
 Amber - (Value boxed) Pressure exceeds high or low limits.
 If system pressure is not within a predetermined value, the HYD L/R
PRES LO alert is displayed on the EAD.

Question 6

Recall what is powered by the two L/R independent hydraulic systems

Answer 6

The hydraulic system is divided into two separate systems, left and
right.
 The left hydraulic system supplies pressure to the left and right inboard
VOL 2
13.20.1 49
spoilers, the left engine thrust reverser and the elevator augmentation
system.
 The right hydraulic system supplies pressure to the left and right
outboard spoilers, the rudder, the right thrust reverser and the landing
gear.
 Both hydraulic systems supply pressure to the slats, flaps, rudder stop
limiter, nose wheel steering, brakes and anti-skid.

Question 7

Recall minimum pre-flight hydraulic quantities for the L and R systems:

Answer 7

Left System – 7qts.

 Right System – 7qts

Question 8

Describe the Hydraulic System Test required on the first flight of the day

Answer 8

Push SDCP HYD cue.
 AUX pump switch – ON
Verify auxiliary hydraulic pump symbol turns green and pressure normal.
 TRANS pump switch – ON
Verify hydraulic power transfer unit symbols turn green and pressure normal.
 TRANS and AUX pump switches - OF

Question 9

Recall the inoperative hydraulic components and considerations for
landing with a complete loss of hydraulics:

Answer 9

If flaps and/or slats are extended, they will remain in their last selected
position.
 Speed brakes/ground spoilers will not be available. Rudder will revert to
manual.
 Emergency Gear Extension Required
 Thrust reversers will not stow