COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gulfstream (Grumman American/ American Aviation) AA-5 Series Aeroplanes AD/AA-5/20 Alternate Static Selector Valve - Inspection NK Applicability: Aeroplanes S/Nos. AA5A-0001 to AA5A-0340 and AA5B-0001 to AA5B-0451. Also all aeroplanes modified by the addition of Gerdes A-1390 alternate static valve shipped from Grumman prior to 19 March 1977. Document: 1. Grumman American SB 160; or 2. FAA AD 77-08-03. Compliance: Within 100 hours' time in service after 31 May 1977.