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Example: Landing Flaps Drive System

We have developed the entire drive system for the Fowler landing flaps of a business turboprop aircraft. The landing flaps drive system consists of:
  • the motor with the central reduction gear box
  • the four actuators with worm gear and ball screw spindles
  • the flexible shafts between the main gear box and the actuators
  • the position sensors and switches
  • the mechanical safety devices
The key features are:
  • actuation force: approx. 4 kN = 900 lbf (each actuator)
  • actuation stroke: approx. 400 mm = 15.7 in
  • actuation time: approx. 30 s

The systems engineering is according to the conditions of RTCA (DO-160).

Kinematics of the Fowler landing flaps

The Fowler landing flaps have three destinctive positions:
  • cruise (completely up and in)
  • start (partially down and out)
  • landing (completely down and out)
Besides the linear flap travel which increaces the wing area there is also a characteristic flap angle (especially in the landing configuration).
cruise
start
landing

CAD image of the general layout

  • motor with gear
  • outboard left-hand actuator
  • inboard actuator
  • outboard right-hand actuator

motor with central reduction gear

actuator with worm gear and ball screw spindle

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