COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Aermacchi - Lockheed AL 60 Series Aeroplanes AD/AL 60/4 Amdt 1 Engine - Exhaust Manifold Failures - Inspection 6/63 Applicability: All models equipped with Continental TSIO-470-B engine. Document: Aermacchi Lockheed 60 SB No. 1. Compliance: At intervals not exceeding 100 hours' time in service after 1 September 1971.