STBY HYD PRESS SWITCHLIGHT (green) (alternate action switch)

PUSH - ON segment (green)

• turns Standby Hydraulic Pump on manually
• Standby Hydraulic Pump functions as a backup source, providing hydraulic pressure to No. 1 hydraulic system

PUSH - ON segment (out)

• turns Standby Hydraulic Pump off manually

ON segment (out) - Standby Hydraulic Pump is off or may be operating automatically if: • No. 1 engine fails, or • Flaps are selected to positions greater than 0° when park brakes selected off and hydraulic reservoir No. 1 not empty • confirmation of operation in this case can be made by observing the STBY HYD PRESS indicator on MFD2

PTU CNTRL SWITCHLIGHT (green) (alternate action switch)

PUSH - ON segment (green)

• Power Transfer Unit (PTU) supplies pressure to the No. 2 hydraulic system
• No. 1 hydraulic system must be operating
• No. 2 hydraulic system must have hydraulic fluid

NOTE: With #1 ENG HYD PUMP caution light on, do not select PTU CNTRL to ON. PUSH - ON segment (out)

• PTU not operating:

ON - segment (green) without pushing

• PTU automatic operation
• the PTU will automatically come on if the: • park brake is selected off, and • flaps are set to more than 0°, and • No. 1 hydraulic pressure is more than 2400 psi, and • No. 2 hydraulic reservoir is not empty

ON - segment (blank) without pushing

• PTU automatically stopped

NOTE: If the PTU is not selected to NORM following the total loss of system #2 fluid, damage to system #2 components may occur, and system #1 pressure may fluctuate about 2100 psi. In this case flaps may become unavailable.

HYD #3 ISOL VLV Switchlight (amber) (alternate action switch)

PUSH - OPEN segment (amber)

• opens isolation valve
• indicates isolation valve is open
• No. 3 hydraulic system is powering the elevators
• when not selected on, the isolation valve will open automatically if No. 1 and No. 2 engines fail

GPWS LANDING FLAP SELECT SWITCH (three position, rotary action)

TURN - 10, 15, or 35 segment (green)

• when the aeroplane flaps select lever is set at less than the Landing Flap Selector Switch (LFSS) setting, a "TOO LOW FLAPS" aural alert will sound when the AGL altitude becomes less than 170 feet.

PILOT’S SIDE PANEL CALLOUT PERTAINING TO GPWS

GPWS FLAP OVERRIDE SWITCH (alternate action)

CROSS HATCHED segment (amber)

• inhibits GPWS mode 4B
• permits 0° flap landings without aural warning
• all other GPWS modes remain active
• when the AGL is less than 50 feet, the override feature automatically cancels