Airworthiness Directives; Airbus Airplanes

We are superseding Airworthiness Directive (AD) 2011-13-11 and AD 2013-16-09 for all Airbus Model A318, A319, A320, and A321 series airplanes. AD 2011-13-11 required an amendment of the airplane flight manual (AFM), repetitive checks of specific centralized fault display system (CFDS) messages, an inspection of the opening sequence of the main landing gear (MLG) door for discrepancies if certain messages are found, and corrective actions if necessary. AD 2013-16-09 required an inspection to determine airplane configuration and part numbers of the landing gear control interface unit and MLG door actuators; and, for affected airplanes, repetitive inspections of the opening sequence of the MLG door, and replacement of the MLG door actuator if necessary. AD 2013-16-09 also provided optional terminating action for the repetitive inspections. This new AD reduces the interval of the MLG door opening sequence inspection, requires replacing or modifying certain MLG door actuators, and also requires a flushing procedure to be performed when installing a new MLG door actuator. This AD was prompted by a determination that the interval of the MLG door opening sequence inspection must be reduced. We are issuing this AD to detect and correct deterioration of the damping ring and associated retaining ring of the MLG door actuator, which can sufficiently increase the friction inside the actuator to restrict opening of the MLG door by gravity, during operation of the landing gear alternate (free-fall) extension system. This condition could prevent the full extension and/or down-locking of the MLG, possibly resulting in MLG collapse during landing and consequent damage to the airplane and injury to occupants.