COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. AD/DHC-8/21 Amdt 1 Engine Rear Mount Strut 10/2001 Applicability: DHC-8 aircraft, Models 102, 103, 106, 201, 202, 301, 311, 314, and 315, with serial numbers 003 through 517; equipped with engine rear mount struts, part numbers 87110016-003, -005, -007, -009, -011, or 8DK1763-001. Requirement: Perform a detailed visual inspection for cracks in the affected engine rear mount strut assemblies listed in the Applicability part of this Directive, on both the left and right engine nacelles. Replace cracked struts before further flight. Replacement of both engine rear mount struts in a nacelle with the new machined struts, part number 87110047-001, terminates the repetitive inspection requirements of this Directive for that nacelle only. Note 1: Termination of the repetitive inspections as specified in this Directive does not alter the operator's approved maintenance program for these rear mount struts. Note 2: Transport Canada AD CF-2001-20 refers. Compliance: Initially, within 1,000 hours time in service since new or within 250 hours time in service after 4 October 2001, whichever occurs later, unless already accomplished. Subsequently, repeat at intervals not to exceed 250 hours time in service. The installation of one new machined strut, part number 87110047-001, in a nacelle, increases the repeat inspection interval to 500 hours time in service for that nacelle only. This Amendment becomes effective on 4 October 2001. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Background: There have been five reported failures of the engine rear mount strut. Investigation has determined that the fracture initiated at one of the rosette welds on the shank of the strut just above the bearing where full weld penetration was not achieved. Amendment 1 is issued in response to a new Transport Canada AD which was prompted by reports that new and reworked struts required by the previous issue of this Directive, continued to fail. Failure of the engine rear mount strut would result in a degradation of the integrity of the engine/nacelle installation. The original issue of this Airworthiness Directive became effective on 23 July 1992. David Alan Villiers Delegate of the Civil Aviation Safety Authority 20 August 2001 The above AD is notified in the Commonwealth of Australia Gazette on 12 September 2001.