COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Propellers - Variable Pitch - McCauley AD/PMC/35 Amdt 1 Propeller Blade Butt Retention Thread - Eddy Current Inspection 13/88 Applicability: All threaded blade McCauley propellers. Requirement: In addition to the dye penetrant inspection described in the appropriate McCauley Propeller Service Manual, conduct an eddy current inspection of the tapered thread butt section of the propeller blade in accordance with technique approved by the Secretary. Eddy Current Technique ATG/NDI/EC/5 constitutes one such technique. Copies of this technique, and test samples may be obtained through regional offices of the Authority. Compliance: 1. Each time propeller is overhauled. 2. Whenever propeller disassembly will allow inspection of the blade butt retention threads. Background: Two recent local failures have occurred at the butt thread section of McCauley propeller blades. One other cracked blade has been detected using eddy current equipment. All subject blades had shot peened and truncated threads. Laboratory tests indicate that the compressive surface formed by the shot peening process may prevent detection of substantial cracks when inspecting with dye penetrants. This Amendment raised to clarify reinspection requirements.