More Lift! Liebherr’s Advanced More Electric Slat / Flap System on Board the A350

At the beginning of this year, the first Airbus A350-1000 aircraft was delivered to Qatar Airways and entered successfully into service. Liebherr-Aerospace delivers alongside the nose landing gear major parts of the high lift system, i.e. slat and flap actuation, comprising newly developed advanced electronic key components.

The purpose of the slat and flap system is to generate more lift of the wing during take-off and landing by extending specific high lift surfaces on the leading edge (slat) or the trailing edge (flap) of the wing, optimizing the aerodynamics.

These high lift surfaces are connected by a transmission system that in term is driven by a power control unit (PCU). The A350 PCU is a hybrid type unit: one input is the hydraulic motor and the other one is the electric motor controlled by the motor control electronic (MCE).

To protect the slat system from excessive torque, a mechanic system torque limiter is installed in the transmission system. On the A350 slat system, this function is performed by an electronic torque sensing unit (TSU) located at the PCU. If the TSU detects an over torque event, the aircraft’s control computers quickly command the motors of the PCU in the reverse direction until the torque in the system is relieved.

On the flap system, our workshare consist of the load sensing drive strut (LSDS) and the moving damper (MD). The LSDS supplies load data to the aircraft and the MD decreases high dynamic peak loads in special failure scenarios.

Furthermore, we equip the A350 with a so-called differential flap setting function to optimize the overall lift distribution in cruise flight to reduce drag and fuel consumption of the aircraft. This function is provided by an active differential gearbox (ADGB) installed in the transmission between the inner and outer flap panel. The ADGB mainly consist of the differential gear, the electric motor with motor control electronic and the electrical power off brake. Therefore, the ADGB represents a unique integration of mechanical and electrical components underlining the capabilities of Liebherr-Aerospace.

Liebherr is supporting Airbus and its operators according to their individual requirements and Liebherr offers worldwide customer service throughout the entire life cycle of the aircraft.