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 47/99 Tail Rotor Blade Skin Material 5/96 TX Applicability: All models with tail rotor blade assembly P/N 047-642-117-105, S/Nos A-1943 to A-2068 inclusive, installed. Requirement: Action in accordance with BHTI ASB 47-96-21. Note 1. FAA AD 96-06-12 refers. Note 2. Installation of approved tail rotor blades, other than those specified in the Applicability, terminates this Directive. Note 3. Installation of tail rotor blades P/N 047-642-117-105M including those serial numbers specified in the Applicability terminates this Directive. Compliance: Prior to further flight after 22 March 1996, thereafter at each Daily Inspection, or at intervals not exceeding 10 hours time in service, whichever occurs first. Note: The Compliance of this Directive is at variance with that of the Requirement Document. Background: The helicopter manufacturer has discovered that certain serial number tail rotor blades were skinned with the incorrect material. This may cause bond line separation and possible loss of the abrasion strip and/or blade tip block.