COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES SAAB SF340 Series Aeroplanes AD/SF340/69 Amdt 1 MLG Support Assembly Bearing Housings 1/2000 Applicability: Model SF 340A, serial numbers 340A-004 though -159. Model 340B, serial numbers 34B-160 through -444. Requirement: Action in accordance with SAAB Aircraft Mandatory Service Bulletin SAAB 340-57- 036. Note: LFV AD 1-146 refers. Compliance: For aircraft with 32,000 total flight cycles or more; within 4,000 flight cycles after 31 December 1999. For aircraft with 24,000 to 32,000 total flight cycles; within 6,000 flight cycles after 31 December 1999. For aircraft with less than 24,000 total flight cycles; perform at scheduled overhauls (at 12,000 or 24,000 total flight cycles) of the landing gears, or within 6,000 flights after 31 December 1999, whichever occurs later. This Amendment becomes effective on 31 December 1999. Background: Corrosion has been found in the inboard and outboard bearing housings of the main landing gear support assembly. The cause is considered to be ingress of moisture between the bearing and bearing housing surface. These fittings are currently classified as Safe Life item and not normally considered as Fatigue Critical. Pitting corrosion may initiate fatigue cracks and lead to a reduction of the fatigue life of the support assembly. Amendment 1 is issued in response to a new LBA AD which introduces an improved NDT method of inspection and a new Requirement document. The original issue of this Airworthiness Directive became effective on 25 March 1999.