Hydraulics

Question 1

How many hydraulic systems are there?

Answer 1

3:
SYSTEM A
SYSTEM B
STANDBY SYSTEM
SH 13.010 pg 1

Question 2

What are they called?

Answer 2

A, B, Standby

SH 13.010 pg 1

Question 3

What is the normal hydraulic pressure range?

Answer 3

3000 psi +/- 200 psi, max 3500

SH 13.010 pg 7

Question 4

What is the purpose of the PTU? When would it operate?

Answer 4

Provide Hydraulic System B pressure sufficient to provide normal rates of
operation for the Autoslats and Leading Edge Devices (LED) in the event the
Hydraulic System B Engine-Driven Pump output pressure drops below 2350 PSI

(SH Section 13.010 Page 9)
Failure of Sys B

Question 5

Are there flight deck indications of PTU operation?

Answer 5

NO

Question 6

What are components specific to the Hydraulic System A?

Answer 6

Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each
Wing), Ground Spoilers, Alternate Brakes, No. 1 Thrust Reverser, Autopilot A,
Normal NWS, Landing Gear, Power Transfer Unit (PTU)
SH 13.010 pg 3
A for lAnding gear

Question 7

What are components specific to the Hydraulic System B?

Answer 7

Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each
Wing), Leading Edge Flaps and Slats, Normal Brakes, No. 2 Thrust Reverser,
Autopilot B, Alternate NWS, Landing Gear Transfer Unit (LGTU), Autoslats, Yaw
Damper, Trailing Edge Flaps (
SH 13.010 pg 3
B for Brakes and flaps and yaw damper

Question 8

What does positioning a FLT CONTROL switch to STBY RUD do? looking for the logic

Answer 8

• turns on the Standby Hydraulic Pump
• supplies pressure to Rudder power control unit
• arms the Standby low pressure light
• Deactivates the flight control low pressure light.

QRH 13.3
SH 13.010 pg 12

Question 9

What is the light logic when a FLT CONT switch is positioned to STBY RUD?

Answer 9

Illuminates STBY RUD ON, FLT CONT annunciatior, and MASTER CAUTION

Extinguishes FLT CONTROL LOW PRESSURE

SH 13.010 pg 13

Question 10

What would cause the automatic operation of the Standby Hydraulic System?

Answer 10

Loss of A and/or B with flaps extended and airborne

• or with wheel speed greater than 60 kts

(Basically, when the plane senses it is in a critical phase of flight)

OR:

The Force Flight Monitor (FFM) trips
SH 13.010 pg 13

Question 11

During normal operations, what could cause variations in hydraulic quantity indications?

Answer 11

High demand on the system, for example:

• System becomes pressurized after engine start
• retraction of landing gear (syst A)
• Extension of LEDs (Syst B)

Also:

-Cold Soaking during cruise flight

SH 13.010 pg 10

Question 12

What would indicate a hydraulic system requires a refill? When would you see this
annunciation, and where is it located?

Answer 12

• A white RF indication will appear next to the hydraulic quantity on the lower DU.
• It will appear if reservoir quantity is below 76%.
• Indication will only show on the ground with both engines shut down or after landing with flaps up during the taxi-in.

SH 13.010 pg 4

Question 13

What pressurizes the Hydraulic System A & B reservoirs?

Answer 13

Regulated bleed air

SH 13.010 pg 3

Question 14

Which hydraulic reservoirs have a standpipe?

Answer 14

A and B

SH 13.010 pg 3

Question 15

What quantity percentage do the associated standpipe(s) protect the reservoir(s) down to?

Answer 15

A - 20% enough to protect electric pump
B - 0% but enough for PTU ops only
SH 13.010 pg 9

Question 16

With zero indicated on the Hydraulic System B quantity indicator, can the PTU still operate?

Answer 16

Yes

Question 17

When is the Standby HYD LOW QUANTITY (amber) light armed? When would it illuminate?

Answer 17

• It is always armed
• it will illuminate when the standby reservoir quantity is below 50%

-accompanied by FLT CONT annunciation and MASTER CAUTION
SH 13.010 pg 12

Question 18

What does a LOW PRESSURE (amber) light indicate? OVERHEAT (amber) light?

Answer 18

LOW PRESSURE = indicate the respective pump output pressure is low. (There are separate low pressure lights for the engine driven and electric pumps on each hydraulic system)

OVERHEAT = an overheat condition is detected in the respective system. (One overheat light per system)

SH 13.010 pg 8

Question 19

Does the Hydraulic System A reservoir standpipe protect against a leak in both the engine
driven pump and electric motor-driven pump? System B?

Answer 19

System A: If a leak develops in the Engine Driven Pump, the Electric Driven
Pump is still available by the Standpipe, providing 20%.
If a leak develops in the Electric Driven Pump, you lose both pumps
and hydraulic drops to 0%.
System B: No. Loss of both Engine and Electric Driven Pumps from a leak
anywhere in the system.
SH 13.010 pg 9

Question 20

What indications, if any, would you see in the event of a Standby Hydraulic system leak?
Does it affect any other system?

Answer 20

-STBY HYD LOW QUANTITY + FLT CONT + MASTER CAUTION will illuminate if standby reservoir drops below 50%

-System B would decrease to 70%, affects system B
SH 13.010 pg 15

Question 21

Should both ELEC hydraulic pump switches be turned on simultaneously?

Answer 21

No, too much of an electrical load. #1 then #2.