The digital duplicated automatic control system SAU-140 is intended for automatic and di-rector control management of aircraft flight for the purpose of reducing the scope of crew's functional duties and creating comfort flight conditions, as well as for automatic engine thrust control.

SAU-140 is designed with consideration for interaction with two types of airborne equip-ment: 
          · analog equipment installed on the existing AN-140 aircrafts;
          · advanced equipment with a digital interface.

The following functions are performed by SAU-140:
  · automatic stabilization of pitch angle;
  · automatic stabilization of roll angle;
  · automatic stabilization of heading angle;
  · automatic stabilization of barometric attitude;
  · automatic roll control with the aid of autopilot control stick (RUA);
  · automatic pitch control with the aid of RUA;
  · setting of specified course with the aid of RUA and specified course indication on the SAU panel;
  · setting-up of the flight level (echelon) by a selector on the SAU panel and indication of specified height level on the SAU panel;
  · generation of the signals warning about approach to the specified flight level and of de-viation from this level;
  · automatic reaching and altitude holding of predetermined flight level;
  · automatic reaching and stabilization of specified course;
  · automatic stabilization of indicated air speed (Vpr) via an elevator;
  · stabilization of Vpr by powerplant thrust control through Electronic System of Power-plant Control (ESUSU-140). The value of stabilized Vpr should be adjusted with the aid of a selector on the SAU panel;
  · horizontal navigation by Satellite Navigation System (SNS) Complex Computer System of Air Navigation (KVSS), beacons VOR/DME, IME/DME;
  · automatic and flight - director landing approach on SNS;
  · automatic and flight - director landing approach (including flight portion with stabilized height) according to II category of ICAO to aerodromes equipped with localizer (KRM) and glidepath (GRM) beacons of SP/ILS system, meeting II category standards, as well as landing approach according to II category of ICAO by KRM and GRM of CATET system;
  · automatic and flight-director landing approach (including flight portion with stabilized height) according to I category of ICAO to aerodromes, equipped with KRM and GRM of SP/ILS, meeting I and II category standards, as well as landing approach according to I category of ICAO by KRM and GRM of CATET system;
  · automatic go-round;
  · flight-director 180-degree overhead approach up to 80-100 m altitude;
  · combined control mode;
  · automatic pitch trimming when automatic control is switched on.
  · SAU-140 is equipped with built-in check means allowing:
                    - automatic preflight checking,
                    - continuous functional checking during flight.

SAU-140 composition:

Name                                                                                      Q-ty
SAU computer                                                                             2
Panel                                                                                          1
Control actuator                                                                         3
Autopilot control stick (RUA)                                                       1
Indicator IN-5-1                                                                          1
Ground preflight check button                                                    1
SAU cut-out button                                                                     2
Autothrottle cut -out button                                                       2
Combined control mode button                                                  2
Go-round button                                                                         2
Sensor unit                                                                                 1

Up-dated SAU-140 variants of various composition can be installed on other types of aircraft: IL-114, MIG-110, TU-334, S-80, AN-32etc.