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 AD/DHC-8/28 Amdt 1 Underwing Fairing Angles 12/95 Applicability: DHC-8 aircraft, Models 311 and 315, serial numbers 240 through 279. Requirement: Inspect the rear face of the left hand and right hand underwing fairing angles for cracks, in accordance with Part A of the Accomplishment Instructions in de Havilland Service Bulletin A8-53-46 Rev A. Note: Transport Canada AD CF-93-10R1 refers. Compliance: Inspect before 6930 flights or within 100 flights from 7 June 1993, which ever occurs later. Re-inspect at intervals not to exceed 6930 flights until replaced with new angles. The Compliance of the initial issue of this Directive remains unchanged. This Amendment is effective from 9 November 1995. Note: If an angle is replaced, the inspection requirement for the new angle reverts to that specified for the standard aircraft, which has a threshold of 40000 flights and a repeat interval of 8194 flights (Maintenance Task 5310/15K refers). Background: A number of titanium fairing angles made for the model 301 were reworked to fit model 311 aircraft during manufacture. The rework entailed weld-filling three fastener holes and re-drilling the holes to suit the model 311 aircraft. The welds were made of commercially pure titanium, with a hardness of one third that of the angle parent material, and there is evidence that in some cases the holes may not have been fully plugged. As a result the fatigue durability of the reworked components P/N 85350927-107SP and -108SP, is unknown and more frequent inspections are required. As the affected aircraft can only be narrowed down to the block of serial numbers specified above, all aircraft within this block must be treated as if they were fitted with the suspect fairing angles. Amendment 1 is issued in response to a revision of the related Country of Origin AD which introduces the Model 315 to the Applicability.