Hydraulics

Question 1

How many hydraulic systems are there?

Answer 1

3

Question 2

What are they called?

Answer 2

A, B, Standby

Question 3

What is the normal hydraulic pressure range?

Answer 3

3000 psi +/- 200 psi, 3500 max

Question 4

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

Answer 4

Provide B Hyd fluid for Autoslats and Leading Edge Devices (LED) When commanded by PTU Control
Valve In the event B Hyd pump pressure drops

Question 5

Are there flight indications of PTU operation?

Answer 5

No

Question 6

What are components specific to the Hydraulic System A?

Answer 6

Ailerons, Rudder, Elevator, Elevator Feel, Flight Spoilers (Two on Each Wing), Ground Spoilers, Alt
Brakes, No. 1 Thrust Reverser, Autopilot A, Normal NWS, Landing Gear, PTU

Question 7

What are components specific to the Hydraulic System B?

Answer 7

Ailerons, Rudder, Elevator, Elevator Feel, Flight Spoilers (Two on Each Wing), LEDS, Brakes, No. 2
Thrust Reverser, Autopilot B, Alternate NWS, Landing Gear Transfer Unit (LGTU), Autoslats, Yaw
Damper, Trailing Edge Flaps

Question 8

What does positioning a FLT CONTROL switch to STBY RUD do?

Answer 8

Manually activates the Standby Hydraulic Pump

Question 9

What is the light logic when positioning a FLT CONTROL switch to STBY RUD?

Answer 9

STBY RUD ON, arms stby low press lgt, extinguish FLT ctrl low press lgt

Question 10

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

Answer 10

a. Loss of sys A or B in flt, Flaps extended, respective FLT CONTROL switch positioned to ON.
b. Or the main PCU Force Flight Monitor (FFM) trips

Question 11

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

Answer 11

a. System A: Retraction gear may result in up to a 20% drop, System B: Extension of LED’s may result in
up to 20%
b. Cold Soaking: additional quantity drop of 5 to 10% up to 20%

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 Refill (RF) on lower DU when quantity is below 75% or less, on gnd after shutdown or taxi in flaps up

Question 13

What pressurizes the Hydraulic System A & B reservoirs?

Answer 13

Regulated bleed air

Question 14

Which hydraulic reservoirs have a standpipe?

Answer 14

A & B

Question 15

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

Answer 15

A: 20% /B: zero
enough for the PTU to fuction

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

Always, When standby reservoir is approximately half empty

Question 18

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

Answer 18

Respective HYD pump low press, Respective electric pump overheat

Question 19

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

Answer 19

No, protects against leak in Eng driven pump allowing operation of elec motor

Question 20

System B?

Answer 20

No, (Provides enough fluid for PTU operation)

Question 21

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

Answer 21

System B Hyd qty drop to approx. 72%

Question 22

Should both ELEC hydraulic pump switches be turned on simultaneously?

Answer 22

No this could overload the system

Question 23

What happens when you place a Flt Control Switch to STBY RUD?

Answer 23

a. Activates STBY Hydraulic Pump
b. Opens STBY Rudder shutoff valve
c. Powers STBY Rudder PCU
d. Extinguishes Low Press light
e. Illuminates STBY Rud on
f. Arms STBY Low press light