Hydraulics

Question 1

Briefly describe the HYD systems.

Answer 1

• There are three separate HYD Systems - L, R, and C. The L and R are identical, and the C is considered “heavy.”
• The L & R are primarily powered by their respective EDPs and backed up by Electric Demand Pumps. The C System is Primarily driven by two Electric Pumps, and reinforced with an Air Driven Pump.
• Any one system can provide aircraft controllability.
• The Reservoirs are pressurized by the bleed air system.

Question 2

What items are Hydraulic Powered?

Answer 2

• L - Flt Ctrls
• R - PES, Norm Brks, Flt Ctrls
• C - E1 - Altn Brks, Nose Wheel Steering (ISLN VALVE)
• C - E2, ADP - LND GR, FLPS, SLTS, HDG, T-Skd, FLT CTRLs
• C - RAT - (CHECK VALVE) - FLT CTRLs

Question 3

How can the pilot see HYD QTY?

Answer 3

• EICAS Status Page
• RF = Re-Fill Prior to Dispatch
• OF = Overfill

Question 4

What does a SYS PRESS light indicate?

Answer 4

• That individual system has inadequate pressure.

Question 5

When does the HDG Activate? What Services are available?

Answer 5

• Dual Main Bus Fail.
• L/R TX, CA FLT INST, STBY AC/DC, HOT, BATT Busses.
• Everything L of ALTN GR, not including EICAS and AutoBrakes.

Question 6

What does an illuminated PRESS light indicate?

OVHT?

Answer 6

• That specific pump is not providing pressure.

- That specific pump is overheated?

Question 7

What does an illuminated QTY light indicate?

Answer 7

• Low Quantity (about 50%)

Question 8

When do Demand Pumps Activate?

Answer 8

• In AUTO, whenever there is high demand, or the primary pump is not providing adequate pressure.
• When selected ON.

Question 9

How much HYD Fluid do we need for dispatch?

Answer 9

• No “RF.”

- Approximately 75%

Question 10

If all three systems have been fucked, will the pilot still be able to break after landing?

Answer 10

• Yes, due to the standpipe in the Center System, and the Reserve Brakes.

Question 11

How does the HYD system’s design increase the probability of breaking and steering ability after fluid loss?

Answer 11

• There is a standpipe in the Center System that ensures fluid and an automatic isolation valve for the C1 Electric Pump, ALTN Brakes, and Nose Wheel Steering Systems to ensure integrity.

Question 12

Describe the RAT.

Answer 12

• Automatically actuated with a dual engine failure.
• Manually activated by pressing the button.
• FLT CNTRLs only.
• Green PRESS = good.
• Min speed 130 kts.
• “Inhibited” on ground.
• Auto deployment arms at 80 its and tilted mains.

Question 13

What is the procedure for HYD Pump Selection, and why?

Answer 13

• Counter Clockwise, slowly, start with R DEMAND ON.
• Clockwise, slowly, OFF.
• To Avoid transferring fluid.