Flaps Electronic Control Unit (FECU) 

The FECU is a typical standalone Flaps Control Unit for an electrically actuated High Lift System of a medium sized turboprop Part-25 aircraft.

System Functions

• Flaps Control Lever Acquisition
• Flaps Position Control
• Wing Tip Brake Control
  
• Assymetry Monitoring
• Jam Monitoring
• Overspeed Protection
• Mode Control
• Status to Indication and Flight Control System
• Fault Isolation and Reporting to Condition Monitoring System
  

Top Level Architecture

The FECU provides two functional lanes, the COMmand lane and the MONitor lane.
The COM lane acquires and validates the pilot commands (via Flaps Control Lever sensor), and controls the flaps  to the commanded detent by controlling the speed of the electrical Flaps Power Drive Unit. The MON lane also acquires and validates the pilot command and compares the actual flaps position with the expected position. In case of mismatch, the MON stops the Flaps motion by activating the Power Off Brake of the drive channel.

The COM Lane consist of a microcontroller implementing the higher level functions, an FPGA implementing the I/O functions, signal conditioning and power conversion. The MON lane consist of an FPGA, signal condioning and power conversion. The FPGA is implementing I/O as well as the uncommanded motion monitoring functions.

The FPGAs COM and MON lanes as well as all other circuits which can lead to erroneous behavior are dissimilar.

Enclosure & Environmental Qualification

The FECU is built into a 3MCU ARINC600 Housing. All sides of the housing are manufactured milled aluminum sheet, optimized for low weight at sufficient stiffness.  Environmental qualification is performed according to DO160g for typical avionics rack environment.