COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Brantly B-2 Series Helicopters AD/B-2/23 Main Rotor Blades - Inspection NK and Replacement Applicability: All model B-2. Requirement: 1. Inspect the inboard ends of the blades for separation between the blade skin and the foam filler. The inspection is to be made by feel and by sounding the blade skin with a large coin or similar metal object. A feeling of sponginess or a dull sound indicates presence of separation. 2. With the aid of a lens of not less than 5X power inspect the inboard end of the blade skins for cracks between the rivet heads. 3. Replace blades P/N B2-248-53 and B2-248-53A, with blades P/N B2-248-53M or B2-248-101; or FAA AD 61-23-1. Compliance: For Para. 1 - Before each flight. (This inspection may be performed and certified by the pilot). For Para. 2 - At intervals not exceeding 25 hours time in service until blades P/N B2-248-53M or B2-248-101 have been fitted. For Para. 3 - For aircraft now on Australian Register replace before further flight if separation more than 12 inches in length is present or if cracks are found around two or more rivet heads, and for new aircraft replace before the issue of C. of A.