Autopilot - Cirrus DESIGN SR20 Information Manual

Section 7
Airplane Description

Autopilot

The airplane may be equipped with the standard S-TEC System
Twenty Autopilot, an optional S-TEC System Thirty Autopilot, or an
optional S-TEC System 55X autopilot. Refer to the applicable FAA
Approved Airplane Flight Manual Supplement and the applicable
Pilot's Guide for additional description as well as specific limitations
and operating procedures for the SR20.
S-TEC System 20 Autopilot (Standard)
The standard SR20 is equipped with an S-TEC System Twenty
Autopilot. This single-axis autopilot system is a rate-based system,
deriving roll axis control inputs from its electric turn coordinator. The
programmer, computer, annunciators, and servo amplifier are
contained entirely within the turn coordinator case. Pilot inputs to the
autopilot are made through the multi-function control knob at the upper
left corner of the turn coordinator. The control knob provides mode
selection, disengage, and turn command functions. The turn
coordinator instrument annunciates system modes. The autopilot may
be disengaged using either the multi-function control knob or by
pressing down on the trim switch on either control yoke handle. The
autopilot drives the aileron trim motor and spring cartridge to control
airplane roll. 28 VDC for autopilot operation is supplied through the 5-
amp AUTOPILOT circuit breaker located on Main Bus 1.
The S-Tec System Twenty Autopilot features:
• Roll Stabilization.
• Turn Command.
• Heading Hold interfaced with DG coupled heading bug.
• NAV/LOC/GPS tracking, HI and LO sensitivity.
S-TEC System 30 Autopilot (Optional)
The optional S-TEC System Thirty Autopilot is a two-axis autopilot
system receives roll axis control inputs from an integral electric turn
coordinator and altitude information from an altitude transducer
plumbed into the static system. The programmer, computer/amplifier,
and annunciators are contained entirely within the turn coordinator
case. Pilot inputs to the autopilot are made through the Multi-function
Control Knob at the upper left of the turn coordinator, through the
Altitude Hold switches on the control yoke handles, and the trim
7-70
Cirrus Design
P/N 13999-002 Info Manual
September 2011
SR20