The European Aviation Safety Agency (EASA) issued an emergency airworthiness directive (AD) to prevent main gear collapse occurrences on Short 360 aircraft.
During investigation of an accident with a Short 360 aircraft, it was established that a main landing gear (MLG) wheel lever failure occurred, due to fatigue cracking. This was initiated by corrosion in the area between the wheel lever bore for the axle bushes and the outer surface of the axle bushes. The absence of cadmium protective treatment on the outer surface of the axle bush was cited as a primary cause of the corrosion and subsequent fatigue cracking.
A review of maintenance repair organisation (MRO) records for the affected Wheel Lever Unit (WLU) provided no tangible evidence that the repair bushes used had the necessary cadmium protective treatment applied. The MRO record review also identified a further three WLU that were lacking the cadmium protective treatment and were therefore susceptible to corrosion and fatigue cracking.
This condition, if not detected and corrected, could lead to failure of the WLU and collapse of the main landing gear, possibly resulting in damage to the airplane and injury to the occupants.
For these reasons, the emergency AD requires identification of the affected WLU and their replacement with serviceable parts.
- EASA EAD 2014-0030-E (PDF)