DCA/CRESCO/8 — Emergency Airworthiness Directive
Pacific Aerospace Corporation Cresco
DCA/CRESCO/8 Engine Mount Structure - Inspection

Applicability: Cresco 08-600 (file photo below) series aircraft equipped with Modification PAC/CT/0210, Installation of PT6A-34AG, or Modification PAC/CT/0291, Installation of PT6A-34.
Requirement: To prevent failure of the engine mount structure, accomplish the following:-Inspect per Pacific Aerospace Corporation Mandatory SB PACSB/CR/040. Also inspect the fuselage longer on in the area where the strut assemblies attach. Pay particular attention around all bolt holes and the steel bush fitting. Rectify any defects found before further flight.
Compliance: Within the next 10 hours TIS and thereafter at intervals not to exceed 300 hours TIS.
Effective Date: 18 June 2004

Background: This AD is prompted by failures of the engine mount strut assemblies. A recent failure occurred during a topdressing operation where the pilot heard a loud "crack" that sounded like a rifle shot. The aircraft’s engine was noticed to have slightly displaced. Following a safe landing, inspection revealed the left hand engine mount strut was broken adjacent to the forward attachment bolt fitting. It has been determined that the strut failed due to fatigue caused by excessive bending in the region of the welds. The manufacturer issued Mandatory Service Bulletin (MSB) PACSB/CR/040 on 15 June 2004 requiring certain inspections of the engine mount assembly. This AD requires compliance with the MSB within the next 10 hours time in service (TIS), and thereafter at intervals not to exceed 300 hours TIS.

FMI: www.caa.govt.nz/fulltext/nzcars/Emergency/DCA_CRESCO_8.pdf