COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Turbine Engines - JT9D Series AD/JT9D/22 First Stage High Pressure Turbine Airseal 2/91 Applicability: JT9D-3A, -7, -7A, -7A(SP), -7AH, -7F, -7H, -7J, -20, -20J engines fitted with P/N 797576, 797576P48, 793707 first stage high pressure turbine airseals. Requirement: 1. Replace first stage high pressure turbine airseals as listed by serial number in PWA Service Bulletin No 5873 Rev 1, Para 2, Part A. 2. Inspect, first stage high pressure turbine airseals not listed by serial number in PWA Service Bulletin No 5873 Rev 1, Para 2, Part A, in accordance with PWA Service Bulletin No 5873 Rev 1, Para 2, Part B. Note: FAA AD 90-23-19 refers. Compliance: 1. At next engine shop visit regardless of planned maintenance action or reason for engine removal. 2. At next access to affected parts. Background: This Directive reflects advice of an uncontained JT9D-7R4H1 engine failure event. The failure was attributed to cracking of an Inconel-718 material airseal. Certain lower rated JT9D models may also be fitted with the same part number airseal. This Directive requires replacement or inspection of those airseals.