COMMONWEALTH OF AUSTRALIA CIVIL AVIATION ORDERS CIVIL AVIATION SAFETY AUTHORITY PART 105 SCHEDULE OF AIRWORTHINESS DIRECTIVES GULFSTREAM (GRUMMAN) G.159 SERIES AEROPLANES AD/G159/30 Amdt 1 Engine Nacelle Firewall - Inspection 10/82 Applicability: All models. Document: Grumman Customer Bulletin No. 293, Amendment 1. Compliance: At intervals not exceeding 150 hours time in service after 31 October 1982. Background: Operators have found additional cracks in the centre of the firewall between the two locations described in the original Customer Bulletin.