The European Aviation Safety Agency (EASA) ordered Airbus landing gear checks to prevent problems in extending and locking of the undercarriage as occurred on a Wizz Air Airbus A320.
On June 8, 2013 an Airbus A320 of Wizz Air was approaching Roma-Ciampino Airport, Italy when the left hand main landing gear failed to fully extend and lock down. The alternate procedures for extending the undercarriage failed and the crew diverted to Roma-Fiumicino Airport for an emergency landing. The aircraft was damaged and three passengers were injured in the evacuation.
Analyses by Airbus have revealed that the Centralized Fault Display System (CFDS) was expected to have generated specific messages prior to the accident, indicating slow operation of the main landing gear (MLG) door opening/closing sequence.
A previously issued airworthiness directive called for repetitive checks of these CFDS messages since these messages may be indicative of wear of certain parts of the MLG.
Investigations showed that the damping ring and associated retaining ring of the MLG door actuator deteriorate. The resultant debris increases the friction inside the actuator which can be sufficiently high to restrict opening of the MLG door even by gravity, during operation of the landing gear alternate (free-fall) extension system.
Since the CFDS messages were not generated, repetitive checks of messages are not effective for aeroplanes fitted with a specific parts as detailed in the AD.
The Emergency AD requires identification of the affected aeroplanes to establish the configuration and, for those aeroplanes, repetitive inspections of the opening sequence of the MLG door actuator and, depending on findings, replacement of the MLG door actuator.