AD 93-23-05

93-23-05 GENERAL ELECTRIC AIRCRAFT ENGINES: Amendment 39-8739. Docket No. 92-ANE-09. Applicability: General Electric (GE) Aircraft Engines Model(s) CT7-5A2 and -7A turboprop engines, incorporating gas generator turbine (GGT) rotor assembly parts and power turbine (PT) disks, as listed by serial number in GE CT7 Turboprop Service Bulletin (SB) A72- 228, Revision 2, and GE CT7 Turboprop SB A72-229, Revision 2, both dated February 7, 1991, installed on, but not limited to, Saab 340A and Casa CN235-10 aircraft. Compliance: Required as indicated, unless accomplished previously. To prevent fatigue cracks that can lead to an uncontained engine failure, accomplish the following: (a) Inspect GGT rotor Stage 1 forward cooling plates, Stage 1 aft cooling plates, Stage 1 disks, Stage 2 forward cooling plates, Stage 2 aft cooling plates, and Stage 2 disks, in accordance with GE CT7 Turboprop SB A72-228, Revision 2, dated February 7, 1991, before exceeding the "max total cycles prior to inspect" limits listed in Tables 1 and 2 of the SB, but not later than December 31, 1995. (1) If evidence of shotpeening is found on any of these parts, prior to further flight, replace the affected parts with serviceable parts. (2) If no evidence of shotpeening is found, prior to further flight, mark the parts with the SB number, in accordance with GE CT7 Turboprop SB A72-228, Revision 2, dated February 7, 1991, and return to service without reducing low cycle fatigue limits. (b) Inspect Stage 3 and Stage 4 PT disks, in accordance with GE CT7 Turboprop SB A72-229, Revision 2, dated February 7, 1991, prior to exceeding the "max total cycles prior to inspect" limits listed in Table 1 of the SB, but not later than December 31, 1995. (1) If evidence of shotpeening is found, prior to further flight, replace the affected disks with serviceable disks. (2) If no evidence of shotpeening is found, prior to further flight, mark the disks with the SB number, in accordancewith GE CT7 Turboprop SB A72-229, Revision 2, dated February 7, 1991, and return to service without reducing low cycle fatigue limits. (c) The inspections, markings, and repairs shall be done in accordance with the following service bulletins:

Document No. Page No. Issue Date GE CT7 Turboprop SB 1-4 & 6 Revision 2 Feb 7, 1991 A72-228 5 & 7-12 Original Jan 30, 1990 Total pages: 12

GE CT7 Turboprop SB 1-3 Revision 2 Feb 7, 1991 A72-229 4-7 Original Jan 30, 1990 Total pages: 7

This incorporation by reference was approved by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from General Electric Aircraft Engines, 1000 Western Avenue, Lynn, MA 01910. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, Attn: Rules Docket No. 92-ANE-09, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC. (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office. (e) Special flight permits may be issued, in accordance with FAR 21.197 and 21.199, to operate the aircraft to a location where the requirements of this AD can be accomplished. (f) This amendment becomes effective on January 10, 1994.