Chapter 11: Hydraulic

Question 1

Hydraulic Fluid Type and Nominal Pressure

Answer 1

Skydrol Hydraulic Fluid

3,000 psi

Question 2

Hydraulic System 1 Components

Answer 2

• One(1) reservoir, pressurized by mechanical piston
• One (1) engine-driven pump
• One (1) AC motor pump
• One (1) regular accumulator
• One (1) parking brake accumulator
• Engine 1 thrust reverser
• Ground spoiler panel 2
• Multi-function spoiler panels 3 and 4
• Left, outboard elevator
• Upper rudder
• Outboard brakes
• Emergency parking brake

Question 3

Hydraulic System 2 Components

Answer 3

• One (1) reservoir, pressurized by mechanical piston
• One (1) engine-driven pump
• One (1) AC motor pump
• One (1) regular accumulator
• One (1) parking brake accumulator
• Engine 2 reverser
• Ground spoiler panel 1
• Multi-function panel 5
• Left and right, inboard ailerons
• Left and right, inboard elevators
• Inboard brakes
• Emergency parking brake
• Nosewheel steering
• Landing gear

Question 4

Hydraulic System 3 Componenents

Answer 4

• One (1) reservoir, pressurized by mechanical piston
• Two (2) AC motor pumps
• One (1) regular accumulator
• Pump unloader valve
• Flow limiter valve
• Left and right, outboard ailerons
• Right, outboard elevator
• Lower rudder

Question 5

Hydraulic Overheat Protection

Answer 5

100 C: “HYD 1(2)(3) HI TEMP” EICAS
125 C: Hyd SOV automatically closes (1)(2); Hyd pumps 3A and 3B automatically turn off (3)
145 C: “HYD 1(2)(3) OVERHEAT” EICAS, crew must manually close SOV (1)(2), or turn off pumps 3A and 3B (3)

*Overheat EICAS messages are inhibited for Hyd 3 during an electrical emergency

Question 6

Hydraulic SOV Turns OFF When…

Answer 6

• ENG PUMP SHUTOFF pushbutton pressed
• Fire handle pulled
• Hydraulic temperature > 125 C
• Engine flameout

Question 7

AC Motor Pump Power Sources

Answer 7

ACMP 1B: AC BUS 2
ACMP 2B: AC BUS 1
ACMP 3A: AC ESS BUSS
ACMP 3B: AC BUS 2

Question 8

AC Motor Pump (1B) (2B) Logic

Answer 8

On Ground:
    -Flaps greater than 0 and
    -Thrust set for takeoff or ground speed > 50 kt
In-Flight:
    -Flaps greater than 0 or
    -EDP or engine failure

ACMP 2B Only:

- On the ground, engine 1 running and parking brake released
- During engine 1 start (N2 > 40%) and less than 6 minutes since parking brake applied

Question 9

PTU Logic

Answer 9

• Engine 2 or EDP Failure
• Flaps not 0 or landing gear not up and locked
• EDP 1 is operational
• Hydraulic reservoir 2 > 12%

Question 10

Hydraulic System 3 Accumulator

Answer 10

During an electrical emergency, provides hydraulic power to the flight controls until the RAT can power AC ESS BUS => ACMP 3A