Autopilot

The autopilot provides pitch and roll control as directed manually by the pilot, or automatically be the VHF navigation or ILS systems. The autopilot will also intercept and capture a pre-selected heading and maintain a constant altitude or pitch attitude. The SP-150 autopilot can also capture a pre-selected altitude and maintain a constant speed during climb or descent.

ENGAGING AND DISENGAGING

ENGAGE INTERLOCKS

To engage the autopilot, the following conditions must be met:

• Essential power on (from airplane generators).

• Turn knob in detent.

• One yaw damper powered (green light illuminated).

ENGAGING

The autopilot switch is locked in the DISENGAGED position unless the interlock circuits are satisfied. The switch is magnetically held in EGNAGED and will spring back to DISENGAGE if their interlock conditions are broken.

DISENGAGING

Each control wheel is equipped with an autopilot disengage switch. These switches are marked AUTOPILOT RELEASE and are located on the outboard horn of each wheel. When either is pressed:

• The autopilot disengages. The AUTOPILOT DISENGAGE lights are extinguished and reset if the switch is held for 1 to 2 seconds or if pressed a second time.

Disengage Warning Lights. Two AUTOPILOT DISENGAGE warning lights, one on each instrument panel, will flash anytime either or both autopilot engage switches disengage for any reason. The lights are extinguished by firmly pressing either warning light or either control hweel release switch.

TURN AND PITCH CONTROL

On the SP-150 autopilot, a turn knob provides roll control; a vetical speed wheel is used for pitch control.

ROLL CHANNEL

The autopilot aileron servomotor actuates the same aileron hydraulic power unit input cables that the pilot actuates when turning the control wheel. The aileron power unit actuates the ailerons and spoilers.

Inputs

The roll channel computer receives the following:

• Pilot selected modes and manual commands from the autopilot controller.

• Roll attitude from the vertical gyro selected to the captain's ADI.

• VOR/LOC deviation from the captain's HSI.

• Selected course and heading from the captain's HSI.

PITCH CHANNEL

Autopilot control of the elevators is by the power control unit (PCU) which hydraulically moves the elevators in response to autopilot commands. The stabilizer is automatically positioned by the autopilot and cruise trim servo motor in response to elevator deflection.

Inpus

The pitch channel computer receives the following:

• Pilot selected modes and manual commands from the autopilot controller.

• Pitch attitude from the vertical gyro selected to the captain's ADI.

• GS deviation from the captain's HSI

• ILS attenuation below 1500 ft RA from the captain's radio altimeter.