COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 47 (All Variants) Series Helicopters AD/BELL 47/72 Amdt 2 Main Rotor Hub Core P/N 47-120-117-1 3/87 Applicability: All model 47 series fitted with P/N 47-120-117-1 hub core. Requirement: Irrespective of the dimensional exclusion given in Part I of Bell SB 47-04-1-73-2, inspect in accordance with Part II of the document. Compliance: At each issue of a new Maintenance Release, for all cores which have exceeded 1200 hours total time-in-service or for which the total time in service is unknown. Background: A crack has been found in the web of a hub core which is exempted by dimensional criteria from the requirement for visual inspection at 100 hourly periods. Amendment 1 included all P/N 47-120-117-1 cores. This amendment brings the compliance periodicity into line with the inspection interval for Maintenance Release.