COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Canada Turbine Engines - PT6T Series AD/PT6T/9 Reduced 2nd and 3rd Stage Compressor Disc Lives 5/92 Applicability: All PT6T series engines and spare compressor discs as listed by serial number in Pratt and Whitney Canada Service Bulletin No. 5266. Requirement: Action in accordance with Pratt and Whitney Canada Service Bulletin No. 5266. Compliance: Effective 30 April 1992. As detailed in requirement document. Background: This Directive requires removal from service, and X-ray inspection of, certain second and third stage compressor discs. This requirement follows advice from the manufacturer that certain discs may have been contaminated with tungsten inclusions during the disc production process.