Caution is needed when rigging the flaps on a Falcon 7X aircraft. Unlike conventional Dassault flap systems, the 7X Flap Power Drive Unit (PDU) is controlled by four individual cable-driven switches from each flap in conjunction with the crew SFAU (Slat Flap Selector Unit) in the cockpit.
The issue is when a switch cable is disconnected for maintenance, replacement or adjustment and the SFAU selector handle in the cockpit is set to clean. The flap drive motor will run as soon as hydraulics are applied, driving the flaps to an over travel condition and causing damage to the flap actuators.
If work is preformed to the flap system and hydraulics are needed, Duncan Aviation highly recommends disconnecting the flap transmission shafts from the PDU to the first 90° gear box in the left and right wheel wells.
Strictly adhere to the caution notes in mechanical and electrical rigging AMM tasks 27-50-00-820-803 and 27-50-00-820-802.
Falcon 7X Service Bulletin 238 adds a switch to the LH IB flap to add over retraction protection and is highly recommended.
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