TAP046: FCU

The FCU is located on the glareshield, and is the short-term interface between the flight crew and the FMGC. It is used to select any flight parameters or modify those selected in the MCDU. The autopilots and autothrust functions may be engaged or disengaged. Different guidance modes can be selected to change various targets these are speed, heading, track, altitude, flight path angle, vertical speed.

 the FCU also includes the two EFIS control panels either side of it and we will explain why shortly.

 The FCU comprises three panels : - one center panel (auto flight control section) which features the   controls and the displays associated with the AFS. - and two symmetrical panels (EFIS control sections) located on the left side  and right side of the center panel. These panels include the controls to change the displays associated respectively with the Captain and  the First Officer EFIS display units. 

The FCU consists of two identical computers (FCU #1 and #2) and are independent of each other. The computers have separate power supplies, with  FCU 1 being prioritised in the event of any electrical issues. FCU1 is for the Captain, FCU 2 for the Copilot.

 In order to ensure segregation of barometric selections and displays, the CAPT and F/O BARO parameters are controlled, in normal operation, independently by the two different FCU - processors.

If both FCUs are serviceable, FCU 1 is active and controls Capt BARO selection, AFS display, AFS and EFIS pushbutton switches

FCU 2 controls only F/O BARO selection.