COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES SAAB SF340 Series Aeroplanes AD/SF340/67 Nose Wheel Hub Heat Treatment 1/99 Applicability: SAAB SF340A, serial numbers SF340A-004 through -159, and 340B, serial numbers 340B-160 through -451. Requirement: Action in accordance with SAAB Aircraft Service Bulletin 340-32-116 Revision 1. Note: LFV AD 1-134 refers. Compliance: Unless already accomplished, before 5 February 1999. This Airworthiness Directive becomes effective on 28 January 1999. Background: The manufacturer of the nose wheel hubs has determined that some hub castings were not properly heat treated during a special process designed to decrease the porosity. The affected parts have a decrease in strength and removal is required as a precaution against possible loose bearing cups and a decreased fatigue life.