AD 97-25-07 Airworthiness Directives; GE Aircraft Engines CT7 Series Turboprop Engines

Models named: CT7-5A2, -7A, - 9B, -9C turboprop. Read the applicability below — it usually turns on serial or part numbers too.

GE Aircraft Engines (GE) Models CT7-5A2, -7A, - 9B, -9C turboprop engines, installed on but not limited to Construcciones Aeronauticas, SA (CASA) CN-235 series and SAAB-SCANIA SF340 series aircraft. Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (l) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required as indicated, unless accomplished previously. To prevent a stage 1 or 2 gas generator turbine (GGT) disk failure, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following: (a) For all stage 1 GGT disks, Part Number (P/N) 6064T06P01, identified in Table 1 of GE (CT7-TP Series) Alert Service Bulletin (ASB) A72-393, Revision 1, dated February 13, 1997, that have accumulated 8,500 or more cycles since new (CSN) on the effective date of this AD, perform a one time eddy current inspection (ECI) for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) Service Bulletin (SB) 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, or not to exceed 3 months after the effective date of this AD, whichever occurs first. (b) For all stage 1 GGT disks, P/N 6064T06P01, identified in Table 1 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated less than 8,500 CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, but not to exceed 9,000 CSN. (c) For all stage 1 GGT disks, P/N 6064T06P01, identified in Table 2 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated 11,500 or more CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, or not to exceed 3 months after the effective date of this AD, whichever occurs first. (d) For all stage 1 GGT disks, P/N 6064T06P01, identified in Table 2 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated less than 11,500 CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, but not to exceed 12,000 CSN. (e) For all stage 2 GGT disks, P/N 6064T12P01, identified in Table 3 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated 8,500 or more CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, or not to exceed 3 months after the effective date of this AD, whichever occurs first. (f) For all stage 2 GGT disks, P/N 6064T12P01, identified in Table 3 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated less than 8,500 CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP [[Page 1903]] Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, but not to exceed 9,000 CSN. (g) For all stage 2 GGT disks, P/N 6064T12P01, identified in Table 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated 11,500 or more CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, or not to exceed 3 months after the effective date of this AD, whichever occurs first. (h) For all stage 2 GGT disks, P/N 6064T12P01, identified in Table 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated less than 11,500 CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, but not to exceed 12,000 CSN. (i) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2 GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated 8,500 or more CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, or not to exceed 3 months after the effective date of this AD, whichever occurs first. (j) For all stage 1 GGT disks, P/N 6064T06P01, and all stage 2 GGT disks, P/N 6064T12P01, not identified in Tables 1 through 4 of GE (CT7-TP Series) ASB A72-393, Revision 1, dated February 13, 1997, that have accumulated less than 8,500 CSN on the effective date of this AD, perform a one time ECI for cracks in accordance with the Accomplishment Instructions of GE (CT7-TP Series) SB 72-390, Revision 1, dated December 11, 1996, at the next GGT module removal, but not to exceed 9,000 CSN. (k) Prior to further flight, remove from service cracked disks, and replace with serviceable parts. (l) 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. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office. (m) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished. (n) The actions required by this AD shall be done in accordance with the following GE (CT7-TP Series) service documents: ------------------------------------------------------------------------ Document No. Pages Revision Date ------------------------------------------------------------------------ ASB A72-393.................. 1-16 1 Feb. 13, 1997. Total pages: 16. SB 72-390.................... 1-6 1 Dec. 11, 1996. Total pages: 6. ------------------------------------------------------------------------ (o) The incorporation by reference of GE (CT7-TP Series) SB 72- 390, dated December 11, 1996, was previously approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of April 15, 1997 (62 FR 15094, March 31, 1997). (p) The incorporation by reference of GE (CT7-TP Series ) ASB A72-393, Revision 1, dated February 13, 1997, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of January 28, 1998. (q) Copies of the service documents may be obtained from GE Aircraft Engines, 1000 Western Ave., Lynn, MA 01910; telephone (781) 594-3140, fax (781) 594-4805. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (r) This amendment becomes effective on January 28, 1998. Issued in Burlington, Massachusetts, on December 23, 1997. Jay J. Pardee, Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 98-71 Filed 1-12-98; 8:45 am] BILLING CODE 4910-13-U