95-13-08: Compressor Turbine Disk

95-13-08 Pratt & Whitney Canada: Amendment 39-9288. Docket 95-ANE-33. Supersedes AD 94-10-02, Amendment 39-8909. Applicability: Pratt & Whitney Canada (PWC) Model PT6A-67D turboprop engines with serial numbers prior to PC-E114100, installed on but not limited to Beech Model 1900D airplanes. NOTE: 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 use the authority provided in paragraph (o) to request approval from the Federal Aviation Administration (FAA). This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any engine from the applicability of this AD. Compliance: Required as indicated, unless accomplished previously. To prevent aircraft handling problems due to imposition of the engine RPM restriction, accomplish the following: (a) For those operators that have previously complied with AD 94-10-02, this AD requires compliance with only paragraph (n). (b) Prior to further flight, amend the Beech Model 1900D Aircraft Flight Manual (AFM), Part Number (P/N) 129-590000-3, by inserting the following requirements between pages 2-4 and 2-5: "ENGINE OPERATING LIMITATIONS Gas Generator RPM (N1) - Continuous operation of the gas generator between 94.0% and 97.1% is prohibited. NOTES 1. This limitation does not prohibit the use of N1's between 94.0% and 97.1% when the pilot in command determines that the power setting is required for the safe operation of the airplane. If such occurrences exceed 5 minutes, the engine(s) must be inspected in accordance with Pratt & Whitney Canada Service Bulletin No. 14128, Revision 3, dated April 19, 1993. 2. This limitation does not prohibit the use of static Take-Off Power and Maximum Continuous Power between 94.0% and 97.1% N1 to meet the required Take-Off performance. If such occurrences exceed 5 minutes, the engine(s) must be inspected in accordance with Pratt & Whitney Canada Service Bulletin No. 14128, Revision 3, dated April 19, 1993. 3. Operation at 94.0% and below, and at 97.1% and above are permitted. Continuous operation at 94.1% through 97.0% is prohibited. 4. "Continuous Operation" means time periods exceeding 5 minutes. 5. High Speed Cruise Power Tables found in the Pilot's Operating Manual may produce N1's in the prohibited range. Flights should be planned using Intermediate or Long RangePower settings. 6. The goal of the operator should be to keep the total time of operation in the prohibited range to the absolute minimum, since the effects of operating between N1's of 94.0% and 97.1% are cumulative. PLACARDS Located in front of the pilot on the aft edge of the glareshield between the Master Caution annunciator and the fire extinguisher control switch: CONTINUOUS OPERATION BETWEEN 94.0% AND 97.1% N1 IS PROHIBITED SEE AFM" (c) Compliance with the requirements of paragraph (b) of this AD may also be accomplished by inserting a copy of this AD into the Beech Model 1900D AFM. (d) Prior to further flight, install the placard as specified in paragraph (b) of this AD. (e) For engines that have not been inspected prior to the effective date of this AD in accordance with PWC SB No. 14128, Revision 1, dated November 13, 1992, or debladed and inspected in accordance with PWC SB No. 14128, Revision 2, dated December 22, 1992, or PWC SB No. 14128, Revision 3, dated April 19, 1993, accomplish the following: (1) For engines with Serial Numbers PC-E114001 to PC-E114044, within 25 hours time in service (TIS) after the effective date of AD 94-10-02, June 15, 1994, deblade the CT disk, inspect the entire disk surface area and fir tree area of the CT blades for cracking and the trailing edge of the blade airfoil section for irregularities, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993. (2) For engines with Serial Numbers PC-E114045 to PC-E114099, within 50 hours TIS after the effective date of AD 94-10-02, June 15, 1994, deblade the CT disk, inspect the entire disk surface area and fir tree area of the CT blades for cracking, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993. (f) For engines that have been inspected in accordance with PWC SB No. 14128, Revision 1, dated November 13, 1992, prior to the effective date of this AD, deblade the CT disk, inspect the entire disk surface area and fir tree area of the CT blades for cracking, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993, as follows: (1) For blade sets with greater than 600 hours TIS since new on the effective date of AD 94-10-02, June 15, 1994, deblade, inspect, and replace, if necessary, within the next 50 hours TIS after the effective date of AD 94-10-02, June 15, 1994. (2) For blade sets with greater than or equal to 250 hours TIS, and less than or equal to 600 hours TIS, since new, on the effective date of AD 94-10-02, June 15, 1994, deblade, inspect, and replace, if necessary, within the next 100 hours TIS after the effective date of AD 94-10-02, June 15, 1994. (3) For blade sets with less than 250 hours TIS since new onthe effective date of AD 94-10-02, June 15, 1994, deblade, inspect, and replace, if necessary, within the next 250 hours TIS after the effective date of AD 94-10-02, June 15, 1994. (g) For uninstalled CT disk and blade assemblies that have not been inspected in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 2, dated December 22, 1992, or PWC SB No. 14128, Revision 3, dated April 19, 1993, in the preceding 250 hours TIS from the effective date of AD 94-10-02, June 15, 1994, deblade the CT disk, inspect the entire disk surface area and fir tree area of CT blades for cracking, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993, prior to installation. (h) For engines with CT disk and blade assemblies that have been debladed and inspected in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 2, dated December 22, 1992, or PWC SB No. 14128, Revision 3, dated April 19, 1993, prior to the effective date of AD 94-10-02, June 15, 1994, within 250 hours TIS since the last deblading and inspection, deblade the CT disk, inspect the entire disk surface area and fir tree area of CT blades for cracking, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993. (i) For CT disk and blade assemblies that have been debladed and inspected in accordance with paragraphs (e), (f), (g), and (h) of this AD, deblade the CT disk, reinspect the entire disk surface area and fir tree area of CT blades for cracking, and replace, if necessary, with serviceable parts, in accordance with the Accomplishment Instructions of PWC SB No. 14128, Revision 3, dated April 19, 1993, at intervals not to exceed 250 hours TIS since the last deblading and inspection performed in accordance with the Accomplishment Instructions of PWC SB No. 14128,Revision 3, dated April 19, 1993. (j) Install a CT stator assembly, a CT shroud housing, and a small exit duct assembly in accordance with PWC SB No. 14132, Revision 1, dated May 12, 1993, at the next shop visit after the effective date of this AD, or within 30 days after the effective date of this AD, whichever occurs first. (k) Install CT blades and feather seals in accordance with PWC SB No. 14142, Revision 1, dated May 12, 1993, at the next shop visit after the effective date of this AD, or 30 days after the effective date of this AD, whichever occurs first. (l) For the purpose of this AD, a shop visit is defined as when major engine flanges are separated. (m) Installation of improved hardware in accordance with paragraphs (j) and (k) of this AD constitutes terminating action for the inspections required by paragraphs (e) through (i) of this AD. (n) For aircraft equipped with engines that have complied with paragraphs (j) and (k) of this AD, or AD 94-10-02, accomplish the following: (1) Remove the amendment to the Beech Model 1900D AFM, P/N 129-590000-3, described in paragraphs (b) or (c) of this AD. (2) Remove the placard described in paragraph (d) of this AD. (o) 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 AD, if any, may be obtained from the Engine Certification Office. (p) 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. (q) The inspections and modifications shall be done in accordance with the following SB's: Document No. Pages Revision Date PWC SB No. 14128 1-5 3 April 19, 1993 Total pages: 5. PWC SB No. 14132 1-6 1 May 12, 1993 Total pages: 6 PWC SB No. 14142 1-7 1 May 12, 1993 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 Pratt & Whitney Canada, 1000 Marie-Victorin, Longueil, Quebec, Canada J4G 1A1. 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 July 12, 1995.