COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES General Electric Turbine Engines - CF6 Series AD/CF6/8 Low Pressure Turbine Cooling Air Manifold 4/87 Applicability: CF6-45,-50 series engines. Requirement: 1. Carry out the requirements of General Electric SB 75-55 Paragraph 2. 2. Inspect left hand side 7th stage low pressure turbine cooling air manifold tubes in accordance with the requirements of General Electric SB 75-58 Paragraphs 2A, 2B, 2C and 2D(4)(b). 3. Remove 7th stage low pressure turbine cooling air tubes and carry out a fluorescent - penetrant inspection in accordance with the requirements of General Electric CF6-50 Task Numbered Shop Manual, GEK 50481. Reference Documents: FAA AD 85-25-56 R1 G.E. SB 75-55 R2 G.E. SB 75-58 G.E. CF6-50 Task Numbered Shop Manual, GEK 50481 Compliance: 1. Unless already accomplished - Prior to 31 March 1987. 2. At intervals not to exceed 250 cycles. 3. At each scheduled engine shop visit. Background: This Directive has been issued to require inspection of the 7th stage low pressure turbine cooling air manifold tubes. Failure of the cooling air manifold tubes could result in an overtemperature condition of the low pressure turbine and subsequent 1st stage turbine disc rupture.