Airworthiness Directives; Airbus Airplanes

We are adopting a new airworthiness directive (AD) for certain Airbus Model A330-200 and -300 series airplanes; Model A340-200 and - 300 series airplanes; and Model A340-541 and -642 airplanes. This final rule was prompted by reports of wing tip brakes (WTBs) losing their braking function in service due to heavy wear on the brake discs. WTBs are designed to stop and hold the mechanical transmission of slats and flaps in certain failure cases. This final rule requires repetitive operational tests of certain WTB pressure-off-brakes (POBs) for performance on the flap and slat systems, and replacement of any affected WTB with a new or serviceable part if the test fails. This final rule also requires eventual replacement of all affected WTBs with a new part, which terminates the repetitive tests. We are issuing this final rule to prevent loss of the WTB braking function, and consequent inability of the flap or slat system to be stopped and held in position during operation, which could result in loss of control of the airplane.