COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters AD/HU 369/90 Tail Rotor Blade Abrasion Strip 5/95 DM Applicability: Model 369 series helicopters, with tail rotor blade assembly part numbers listed in McDonnell Douglas Helicopter Systems SIN HN-238, DN-187, EN-80, or FN-66. Requirement: 1. Inspect the tail rotor blade abrasion strip for debonding from the tail rotor blade. Prior to conducting the inspections, remove any abrasion tape from the tail rotor blade. If the inspection reveals debonding, replace the tail rotor blade with an airworthy blade that has been modified by installation of rivets, and install 304 stainless steel abrasion tape (.0027 inch thick) over the inboard end of the abrasion strip in accordance with steps B through H of Part I of the Accomplishment Instructions of McDonnell Douglas SIN HN-238, DN-187, EN-80, or FN-66. If the inspection reveals no debonding, install 304 stainless steel abrasion tape (.0027 inch thick) over the inboard end of the abrasion strip in accordance with steps B through H of Part I of the Accomplishment Instructions of McDonnell Douglas Helicopter Systems SIN HN-238, DN-187, EN-80, or FN-66. 2. Replace the affected tail rotor blades in shipsets with tail rotor blades that contain the new-design abrasion strips in accordance with Part II of the Accomplishment Instructions of SIN HN-238, DN-187, EN-80, or FN-66. Once the new-design abrasion strips are installed on the tail rotor blades, the tail rotor assembly part number changes as follows: Old Tail Rotor Assembly No New Tail Rotor Assembly No 369A1613-7 369A1613-11 369A1613-503 369A1613-507 369A1613-505 369A1613-507 369A1613-509 369A1613-507 369D21606 369D21606-511 369D21606-509 369D21606-511 369D21613-11 369D21613-11N 369D21613-31 369D21613-31N 369D21613-41 369D21613-61 369D21613-51 369D21613-61 369D21613-71 369D21613-61 COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES 369D21615 369D21615-N 369D21615-21 369D21615-31 369D21615-41 369D21615-31 421-088 421-088-11 Note: FAA AD 95-03-11 Amdt 39-9147 refers. Compliance: 1. Unless already accomplished, within 25 hours time in service after 15 March 1995 or prior to 15 June 1995, whichever occurs first, and thereafter at intervals not to exceed 100 hours time in service; until Requirement 2 of this Directive is accomplished. 2. Within 1,000 hours time in service after 15 March 1995. Background: The FAA received several reports of incidents where tail rotor blade riveted abrasion strips debonded and separated during flight, which resulted in a severe out-of-balance condition and subsequent separation of the tail rotor gearbox from the helicopter.