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/15 High Pressure Turbine Airseal 12/86 TX Applicability: JT9D-7R4D, E models. Requirement: Carry out the requirements of Pratt and Whitney ASB JT9D-7R4-72-318, Paragraph 2 "Accomplishment Instructions". Compliance: According to a program agreed to by the Secretary. Effective: 1 December 1986. Background: This Directive has been issued to require compliance with the Accomplishment Instructions of P.W.A. A.S.B. JT9D-7R4-72-318. The A.S.B. details inspection and modification of the high pressure turbine to preclude cracking of the stage 1-2 airseal.