AD 92-26-08

92-26-08 ALLIED-SIGNAL INC., GARRETT ENGINE DIVISION: Amendment 39-8606. Docket 92-ANE-58. Applicability: Allied-Signal Inc., Garrett Engine Division, Model TPE331-1, -2, -2UA, -3U, -3UW, -5, -5A, -6, and -6A turboprop and Model TSE331-3U turboshaft engines incorporating third stage stator assemblies, Part Number (P/N) 868379-3, repaired at National Flight Services between February 20, 1990, and April 6, 1992, and identified by serial numbers listed in National Flight Services Alert Bulletin No. NF331-A72-11921, dated November 9, 1992. These engines are installed on but not limited to Mitsubishi MU-2B series (MU-2 series); Construcciones Aeronauticas, S.A. (CASA) C-212 series; Fairchild SA226 series (Swearingen Merlin and Metro series); Prop-Jets, Inc. Model 400; Twin Commander 680 and 690 (Jetprop Commander); Rockwell Commander S-2R; Shorts Brothers and Harland, Ltd. SC7 (Skyvan); Dornier 228 series; Beech 18 and 45 series and Models JRB-6, 3N, 3NM, 3TM, and B100; Pilatus PC-6series (Fairchild Porter, Peacemaker); De Havilland Model DH 104 series 7AXC (Dove); and Ayres S-2R series airplanes; and Sikorsky S-55 series helicopters. Compliance: Required as indicated, unless accomplished previously. To prevent an uncontained failure of the third stage turbine wheel, accomplish the following: (a) Replace affected third stage stator assemblies, P/N 868379-3, with serviceable assemblies in accordance with the following schedule:

Third Stage Stator Cycles in Service Since Repair by National Flight Services Replacement Schedule 900 or more cycles Within 50 cycles in service after the effective date of this AD 450 to 899 cycles Within 150 cycles in service after the effective date of this AD, but not to exceed 950 cycles Less than 450 cycles Prior to accumulating 600 cycles

NOTE: The FAA has determined that cracking of third stage stator assemblies is related to operating cycles, rather than operating hours. (b) If cycles cannotbe determined, calculate cycles by multiplying third stage stator assembly hours time in service by 1.5. (c) An alternative method of compliance or adjustment of the initial compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft 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, Los Angeles Aircraft Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Los Angeles Aircraft Certification Office. (d) 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. (e) Third stage stator assemblies, P/N 868379-3, repaired at National Flight Services between February 20, 1990, and April 6, 1992, are identified by serial numbers listed in the following alert bulletin:

Document No. Pages Date NF331-A72-11921 Total pages: 10. 1-10 November 9, 1992

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 National Flight Services, Inc., 10971 E. Airport Service Road, Swanton, Ohio 43558; telephone (419) 865-2311. 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. (f) This amendment becomes effective July 15, 1993, to all persons except those persons to whom it was made immediately effective by priority letter AD 92-26-08, issued December 16, 1992, which contained the requirements of this amendment.