COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Propellers - Variable Pitch - Hamilton Standard AD/PHS/21 Amdt 1 Blade Spar Taper Bore 8/96 DM Applicability: All model 14RF, 14SF, and 6/5500/F Series propellers with blade and pin assemblies with manufacturing serial number less than 885718. Note: These propellers are fitted to Embraer EMB-120, DHC-8-100 and 300, Aerospatiale ATR42, CASA CN-235, SAAB SF340, BAe ATP, and Canadair CL215T/CL415T Series aircraft. Requirement: Action in accordance with the technical requirements of FAA AD 96-08-02 Amendment 39-9568. The ultrasonic shear wave inspections required by this Directive must be carried out by an appropriately qualified NDT Authority holder. Note 1: FAA AD 96-08-02 Amdt 39-9568 supersedes FAA AD 96-01-01 Amdt 39- 9477 which superseded FAA Telegraphic AD T95-18-51 and FAA Priority Letter AD 95-18-06R1. Note 2: Initial issue of this Directive cancelled AD/PHS/17 Amdt 2 and AD/PHS/19 Amdt 1. Note 3: All blade and pin assemblies previously inspected in accordance with AD/PHS/17 Amdt 2, AD/PHS/19 Amdt 1 or AD/PHS/21 are required to be re- inspected in accordance with this Directive. Compliance: Effective 29 May 1996; as detailed in the Requirement Document. Background: A recent accident involving an Embraer EMB-120 aircraft has been attributed to fatigue cracking in the blade taper bore area which resulted in the liberation of a blade during flight. The initial Directive was issued to require an improved taper bore ultrasonic shear wave inspection and also to reduce various re-inspection intervals that are dependent on which aircraft propeller model is being inspected and provides an inspection to re-evaluate the serviceability of blade and pin assemblies previously rejected in accordance with AD/PHS/19 Amdt 1. Amendment 1 requires a blade repair that constitutes terminating action for the repetitive taper bore ultrasonic inspection requirement. The initial issue of this Airworthiness Directive became effective on 27 February 1996.