AB 412 helicopters equipped with hydraulic external hoist part number (P/N) BL10300-6
EASA EAD 2014-0063-E: AgustaWestland AB 412 helicopters: Equipment / Furnishings - Utility Hydraulic System / Pressure Line Pump and Filter - Inspection / Replacement
During hoist operation of an AB 412 helicopter equipped with hydraulic external hoist P/N BL10300-60, failure of pressure line pump P/N 1-8072 Rev. A was reported.
Preliminary investigations revealed that unusual wear of an internal subcomponent generated metal particles which caused the pump to fail. The root cause of this wear is under investigation, but has not yet been determined.
This condition, if not detected and corrected, could lead to further occurrences of pump failure, possibly resulting in personal injury or hoisting accidents.
To address this unsafe condition, AgustaWestland issued Bollettino Tecnico (BT) 412-140 providing instructions for inspection of filter P/N 1-12028 installed on the pressure line of the utility hydraulic system.
For the reason described above, this AD requires repetitive inspections of the filter for presence of metal particles and, in case of findings, replacement of the pressure line pump.
Pending final investigation results, this AD is considered an interim action and further AD action may follow.