Hydraulic Systems

Question 1

Can hydraulic fluid be transferred between the systems?

Answer 1

No

Question 2

How many hydraulic pumps are on the airplane?

Answer 2

6 total

• 2 engine driven pumps
• 4 AC motor pumps (ACMP’s)

Question 3

When will ACMP 1 or 2 automatically activate?

Answer 3

Ground:

• Flaps >0 and Thrust Levers set to T/O or
• Groundspeed > 50 kts

Inflight:

• Engine failure or EDP failure
• Flaps >0

Question 4

What is the primary purpose of HYD 3 system?

Answer 4

Backup for the Primary Flight Controls

Question 5

When will the PTU automatically activate?

Answer 5

During takeoff and landing with flaps >0 or if

Engine 2 fails or EDP 2 fails

Question 6

What happens when the fluid tempurature reaches 125 degrees C?

Answer 6

The Shutoff Valve (SoV). This isolates the EDP 2 from the respective hydraulic flow line

Question 7

What is the purpose of the accumulator?

Answer 7

• Helps to maintain constant pressure by covering transient demands
• Helps to avoid pump cavitation

Question 8

Why are HYD ACMP 3A & B pump switch positions “On” and “Auto” Respectively?

Answer 8

HYD ACMP 3A pump is primary and has no automation

HYD ACMP 3B pump is a backup and automatically activates if ACMP 3A fails

Question 9

What are the two Hyd Sys 3 dedicated valves used in an electrtical emergency to avoid overload in the RAT?

Answer 9

Pump Unloader Valve

Flow Limiter Valve

Question 10

What, if any, HYD ACMP will function if the RAT is the only power source?

Answer 10

HYD ACMP 3A only

Question 11

In an electrical emergency can HYD 3 system

power requirements overload the RAT?

Answer 11

No

A flow limiter valve is used to reduce flow and limits

pump electrical power draw to prevent RAT stall

Question 12

At what temperature will the Shutoff Valve automatically Actuate?

Answer 12

125 degrees C

Question 13

What are the basic components of the hydraulic system?

Answer 13

• Reservoir
• Pumps
• Accumulator

Question 14

What is the primary purpose of the PTU?

Answer 14

To allow landing gear retraction in the event of an ENG 2 or EDP 2 failure

Question 15

What are some important items controlled by HYD 2 system?

Answer 15

• Landing gear
• Nose wheel steering
• Inboard brakes

Question 16

When will the HYD 2 HI TEMP EICAS Caution message by displayed?

Answer 16

100 degrees C

Question 17

What systems use hydraulic power?

Answer 17

• Flight controls
• Spoilers
• Landing gear
• Nose wheel steering
• Wheel brakes
• Thrust reversers

Question 19

When will the Electric Hydraulic Pump 2 automatically shutoff?

Answer 19

6 minutes after parking break has been set

Question 20

When will the Electic Hydraulic Pump 2 automatically activate on the ground?

Answer 20

Engine 1 running and parking break released

During Eng 1 start (once N2 reaches 40%) if parking break has been set within the last 6 minutes

NOTE: Electric Pump shuts off automatically in 6 minutes after Parking Break

Question 21

How long will the Hydraulic Pumps be active during landing operations?

Answer 21

60 seconds (to avoid pressure variations in an event of engine failure)

Question 22

What is the primary source of power in the Hydraulic System?

Answer 22

Engine Driven Pump (EDP)

Question 23

Where are the Quantity Measuring and Tempurature Transducers located?

Answer 23

Inside their respective Reservoirs

Question 24

At what tempurature will the HYD 2 OVERHEAT EICAS warning message appear?

Answer 24

145 degrees C

Question 25

What is the PTU?

Answer 25

Power Transfer Unit

Mechanical pump that uses HYD 1 power to provide HYD 2 pressure

Question 26

How many Hydraulic systems are on the plane?

Answer 26

3 independent systems

Question 27

In an electrical emergency what provides hydraulic

pressure to flight control until the RAT comes online?

Answer 27

HYD 3 accumulator

After 8 seconds the RAT will power ACMP 3