B737 Flight Control Panel

FLIGHT CONTROL Switches

• STBY RUD: Activates standby hydraulic system pump and opens standby rudder shutoff valve to pressurize standby rudder power control unit.
• OFF: Closes flight control shutoff valve, isolating ailerons, elevators, and rudder from associated hydraulic system pressure.
• ON (guarded position): Normal operating position.

Flight Control LOW PRESSURE Lights

• Illuminated (amber):
  • Indicates low hydraulic system (A or B) pressure to ailerons, elevator, and rudder.
  • Deactivated when associated FLIGHT CONTROL switch is positioned to STBY RUD and standby rudder shutoff valve opens.

Flight SPOILER Switches

• ON (guarded position): Normal operating position.
• OFF: Closes the respective flight spoiler shutoff valve.
• Note: Used for maintenance purposes only.

YAW DAMPER Light

• Illuminated (amber): Yaw damper is not engaged.

YAW DAMPER Switch

• OFF: Disengages yaw damper.
• ON:
  • Engages main yaw damper to main rudder power control unit if the B FLT CONTROL switch is in the ON position.
  • Engages standby yaw damper to standby rudder power control unit if both the A and B FLT CONTROL switches are in the STBY RUD position.

STANDBY HYDRAULIC LOW QUANTITY Light

• Illuminated (amber):
  • Indicates low quantity in standby hydraulic reservoir.
  • Always armed.

STANDBY HYDRAULIC LOW PRESSURE Light

• Illuminated (amber):
  • Indicates output pressure of standby pump is low.
  • Armed only when standby pump operation has been selected or automatic standby function is activated.

STBY RUD ON Light

• Illuminated (amber): Indicates the standby rudder system is commanded on to pressurize the standby rudder power control unit.

ALTERNATE FLAPS Master Switch

• OFF (guarded position): Normal operating position.
• ARM: Closes TE flap bypass valve, activates standby pump, and arms the ALTERNATE FLAPS position switch.

ALTERNATE FLAPS Position Switch

• Functions only when the ALTERNATE FLAPS master switch is in ARM.
  • UP:
    • Electrically retracts TE flaps.
    • LE devices remain extended and cannot be retracted by the alternate flaps system.
  • OFF: Normal operating position.
  • DOWN (spring-loaded to OFF):
    • (Momentary) Fully extends LE devices using standby hydraulic pressure.
    • (Hold) Electrically extends TE flaps until released.

Feel Differential Pressure (FEEL DIFF PRESS) Light

• Armed when the TE flaps are up or down.
• Illuminated (amber):
  • Indicates excessive differential pressure in the elevator feel computer.
  • Note: Excessive differential pressure can be caused by erroneous activation of the Elevator Feel Shift module.

Speed Trim Failure (SPEED TRIM FAIL) Light

• Illuminated (amber):
  • Indicates failure of the Speed Trim System (Speed Trim function or MCAS function). If one function fails, the other function is inhibited.
  • Indicates failure of a single FCC channel when MASTER CAUTION recall is activated, and light extinguishes when Master Caution System is reset.

Mach Trim Failure (MACH TRIM FAIL) Light

• Illuminated (amber):
  • Indicates failure of the mach trim system.
  • Indicates failure of a single FCC channel when MASTER CAUTION light recall is activated, and light extinguishes when master caution system is reset.

Automatic Slat Failure (AUTO SLAT FAIL) Light

• Illuminated (amber):
  • Indicates failure of the auto slat system.
  • Indicates failure of a single Stall Management/Yaw Damper (SMYD) computer when illuminated during MASTER CAUTION recall and extinguishes when master caution system is reset.

SPOILERS Light

• Illuminated (amber):
  • Activated by signal from spoiler control electronics unit.
  • Indicates spoiler system fault.