Airworthiness Directive · Amendment 39-15018 · General Electric Company CT7-5, -7, and -9 Series Turboprop Engines
General Electric Company CT7-5, -7, and -9 Series Turboprop Engines
This AD applies to General Electric Company (GE) CT7-5A2/-5A3/-7A/-7A1/-9B/-9B1/-9B2/-9C/-9C3/-9D/-9D2 turboprop engines with stage 2 turbine aft cooling plates, part number (P/N) 6064T07P01, 6064T07P02, 6064T07P05, or 6068T36P01 installed. These engines are installed on, but not limited to, Construcciones Aeronauticas, SA CN-235 series and SAAB Aircraft AB SF340 series airplanes.
The FAA is superseding an existing airworthiness directive (AD) for General Electric Company (GE) CT7-5A2, -5A3, -7A, -7A1, -9B, - 9B1, and -9B2, -9C, -9C3, -9D, and -9D2 turboprop engines, with certain part number (P/N) and serial number stage 2 turbine aft cooling plates installed. That AD currently requires a onetime eddy current inspection (ECI) of boltholes in certain P/N stage 2 turbine aft cooling plates. This AD expands the population of affected CT7 turboprop engine models, but reduces the number of cooling plates affected. It also requires a onetime ECI of boltholes in certain P/N stage 2 turbine aft cooling plates with specific serial numbers. This AD results from the manufacturer expanding the list of affected engine models and identifying the affected stage 2 turbine aft cooling plates by serial number. We are issuing this AD to prevent separation of the stage 2 turbine aft cooling plate, resulting in uncontained engine failure and damage to the airplane.
You are responsible for having the actions required by this AD performed at the next engine or hot section module shop visit, but before accumulating an additional 6,000 cycles-in-service after the effective date of the AD, unless already done.
Perform a onetime ECI of the stage 2 turbine aft cooling plates P/N 6064T07P01, 6064T07P02, 6064T07P05, or 6068T36P01, that are listed by serial number in Section 4, Appendix A, of GE Alert Service Bulletin (ASB) No. CT7-TP S/B 72-A0464, Revision 04, dated December 12, 2005, and that will be returned to service. Use 3.B.(1) through 3.B.(3) of GE ASB No. CT7-TP S/B 72-A0464, Revision 4, dated December 12, 2005 to perform the inspection.
(g) For stage 2 turbine aft cooling plates that do not pass the Return to Service Criteria, do either of the following:
(1) Replace the stage 2 turbine aft cooling plate with a new cooling plate that has a serial number that is not listed in Section 4, Appendix A, of GE ASB No. CT7-TP S/B 72-A0464, Revision 04, dated December 12, 2005, or
(2) Replace the stage 2 turbine aft cooling plate with a cooling plate that meets the acceptance criteria of 3.B.(1) through 3.B.(3) of GE ASB No. CT7-TP S/B 72-A0464, Revision 4, dated December 12, 2005.
(h) After the effective date of this AD, do not install any stage 2 turbine aft cooling plates with serial numbers identified in Section 4, Appendix A, without inspecting the cooling plate as specified in 3.B.(1) through 3.B.(3) of GE ASB No. CT7-TP S/B 72-A0464 Revision 04, December 12, 2005.
(i) Eddy current inspections of the stage 2 turbine aft cooling plate boltholes done before the effective date of this AD that use GE ASB No. CT7-TP S/B 72-A0464, dated February 25, 2003; or Revision 1, dated March 12, 2003; or Revision 2, dated May 9, 2003; or Revision 3, dated July 23, 2004, comply with the requirements specified in this AD.
For the purposes of this AD, an engine or hot section module shop visit is defined as the introduction of the engine or hot section module into a shop that includes separating major case flanges.
