COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pilatus Britten-Norman BN-2 Series Aeroplanes AD/BN-2/39 Aileron Mass Balance Tube - Inspection NK Applicability: All models. Document: Britten Norman SB No. BN-2/SB.98. Compliance: Within 100 hours time in service after 31 January 1977 or not later than 1 March 1977 whichever occurs first.