COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Rolls Royce Turbine Engines - Spey Series AD/RRT-S/9 Transply Combustion Liners 7/86 Applicability: Spey Mk. 555 Series engines fitted with Mod 6012 or Mod 6123 combustors. Requirement: Replace Mod 6012 or Mod 6123 combustors in accordance with Rolls Royce SB Sp 72-1001. Compliance: Not later than 3,500 hours combustor time since new. Background: This Directive has been issued to require replacement of Transply combustion liners. Rolls Royce advise, service experience with Mod. 6012 standard combustors indicates Transply combustors are experiencing circumferential cracking in the head and barrel sections. Service experience with boroscope inspection of Transply combustors has proven unsatisfactory, therefore a life limit of 3,500 hours is required.