Hydraulics

Question 1

What is backup for HYD SYS 1

Answer 1

SPU - Standby Pump Unit

Question 2

Hydraulic system pressure?

Answer 2

3000psi

Question 3

SPU conditions for activation

Answer 3

#1 engine fails during flight
Flaps are selected to a position greater than 0 degrees when parking brake is off and HYD reservoir in #1 system is not empty (assists flap extension / retraction)

Question 4

Standby hydraulic pump overheat condition results in what annunciator

Answer 4

STBY HYD PUMP HOT

Question 5

What does PTU stand for

Answer 5

Power transfer unit

Question 6

PTU conditions for auto activation on ground

Answer 6

1 EDP > 2400PSI

#2 HYD SYS has fluid
Park brake released
Flaps are more than 0 deg

Question 7

PTU conditions for auto activation in air

Answer 7

#1 EDP > 2400PSI and,
#2  HYD SYS has fluid and,
Flaps selected to more than 0 deg and,
Park brake off and,
#2 engine oil pressure is low or #2 HYD pressure low

Question 8

Alternate Landing Gear system does what?

Answer 8

Provides means for alternate gear extension

Question 9

Hydraulic QTY # 1

Answer 9

8QTS

Question 10

Hydraulic QTY # 2

Answer 10

12 QTS

Question 11

Minimum hydraulic system quantities, 1,2 &3

Answer 11

1 - 40%
2 - 40%
3 - 45%

Question 12

1 HYD SYS supplies? (6)

Answer 12

~~~
Flaps
Anti skid
Inboard roll spoiler
Rudder
Elevator
PTU

Question 13

2 HYD SYS supplies (6)

Answer 13

LDG Gear
Outboard roll spoilers
Nose wheel steering
Emergency and parking brake
Rudder PCU upper
Elevator Center PCU's

Question 14

Where is HYD fluid temp measured?

Answer 14

In the reservoirs

Question 15

When does Priority valve close? What does it do?

Answer 15

#1 HYD SYS pressure <2100psi
Shuts off press to Flaps & PTU and maintains pressure to primary flight controls and brakes

Question 16

When does STBY hydraulic pump activate (flaps) and what powers it?

Answer 16

Manual selection by crew or
A failure of engine #1 &
#1 reservoir is not empty &
Park brake is off &
Flaps > 0*
AC power is available

115VAC motor powered by Right 115VAC bus

Question 17

What pressurises the #3 Hydraulic Standby Accumulator

Answer 17

28VDC motor driven pump to between 2600-3250psi

Question 18

When does the standby pump activate

Answer 18

System pressure drops below 2600psi

Question 19

3 HYD PUMP light

Answer 19

System pressure drops below 900PSI or the DCMP has been operating continuously for more than 60 seconds

Question 20

What powers the Firewall Shut Off Valves and when will they close?

Answer 20

Battery Bus

• When the Engine Pull Fuel / HYD handle is pulled
• QTY is low in reservoir or
• Hydraulic fluid overheats (#1 / #2 HYD FLUID HOT)

Question 21

When does the isolation valve close in both systems and what does it restrict HYD fluid flow to?

Answer 21

When the fluid quantity is low, the valve closes.

Removes brakes and inboard flight spoilers in #1
Removes Outboard spoilers, landing gear & normal steering in #2

Question 22

What happens if #2 system pressure does not reach the lower pressure limit 5 seconds after PTU activation?

Answer 22

PTU auto operation will stop and wont reactivate.

Question 23

What does #3 HYD system operate?

Answer 23

L & R inboard elevator PCU’s

Question 24

How does #3 HYD system operate automatically and manually?

Answer 24

Auto - #1 &or #2 systems lose pressure or
Both engines fail.

Manual - Pushing HYD #3 ISOL VLV switchlight

Question 25

How does #3 HYD system develop hydraulic pressure and what powers it?

Answer 25

A DC Motor Pump DCMP and an accumulator located near the tail of the aircraft. Powered by the Standby Battery

Question 26

What does ELEVATOR PRESS caution light mean?

Answer 26

All 3 Hydraulic systems are supplying pressure to the Rudder PCU’s

Question 27

What doe the priority valve do and when does it activate?

Answer 27

System 1,
If HYD 1 system pressure drops below 2100PSI, it shuts off power to the flaps and PTU.