2003-11-09: Centrifugal Compressor Intake Wheel Blades

2003-11-09 Turbomeca: Amendment 39-13168. Docket No. 99-NE-12-AD. Applicability: This airworthiness directive (AD) is applicable to Turbomeca Turmo IV A and IV C series turboshaft engines. These engines are installed on but not limited to Aerospatiale SA 330--PUMA helicopters. Note 1: This 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 (d) 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. Compliance: Compliance is required as indicated, unless already done; To prevent centrifugal compressor intake wheel blade cracks, which can result in in-flight engine power loss or shutdown, do the following: (a) For engines that have been modified to TU 197 standard, but have not been modified to TU 191 or TU 224 standard, do the following: (1) Remove modification TU 197 and install modification TU 224 in accordance with Turmo IV SB 249 72 0117, dated March 11, 2001, within the next 50 cycles or six months after the effective date of the AD, whichever occurs first. (2) Within 1,000 flight hours (FH) after the installation of modification TU 224 standard, do the following: (i) Perform a visual inspection and an ultrasonic inspection (USI) in accordance with paragraph 2.B.(3) of Turbomeca Turmo IV SB 249 72 0100, Update 4, dated January 25, 2000. (ii) Thereafter, perform a visual inspection and a USI at intervals not to exceed 1,000 FH in accordance with paragraph 2.B.(3) of Turbomeca Turmo IV SB 249 72 0100, Update 4, dated January 25, 2000. (b) For engines that have not been modified to TU 191, TU 197, or TU 224 standard, do the following in accordance with Turbomeca Turmo IV SB 249 72 0100, Update 4, dated January 25, 2000: (1) For centrifugal compressor intake wheels that, on the effective date of this AD, have been operated for more than 250 FH since the last inspection of the centrifugal compressor intake wheel blades, do the following: (i) Perform an initial borescope inspection of the blades for evidence of corrosion within the next 50 FH, or six months after the effective date of this AD, whichever occurs first, in accordance with paragraph 2.B.(1) of the SB. (ii) If corrosion is found, perform an eddy current inspection (ECI) or USI, as applicable, of the blades for cracks within 50 FH after the borescope inspection performed in accordance with paragraph 2.B.(3) of the SB, and if necessary, replace with serviceable parts. (iii) If corrosion is not found, perform an ECI or USI, as applicable, of the blades for cracks within 250 FH after the borescope inspection performed in accordance with paragraph (b)(1)(i) of this AD, and if necessary, replace with serviceable parts. (iv) Thereafter, perform borescope inspections and ECIs or USIs, as applicable, of the blades for cracks and evidence of corrosion, alternating at intervals not to exceed 250 FH since the last inspection. (v) Remove from service centrifugal compressor intake wheels found cracked and replace with serviceable parts. (2) For centrifugal compressor intake wheels that, upon the effective date of this AD, have been operated for less than or equal to 250 FH since the last inspection of the blades, do the following: (i) Perform an initial borescope inspection of the blades for evidence of corrosion prior to accumulating 250 FH since the last inspection of the blades in accordance withparagraph 2.B.(1) of the SB. (ii) If corrosion is found, perform an ECI or USI, as applicable, of the blades for cracks, and, if necessary, replace with serviceable parts, within 50 FH after the borescope inspection performed in accordance with paragraph 2.B.(3) of the SB. (iii) If corrosion is not found, perform an ECI or USI, as applicable, of the blades for cracks, and, if necessary, replace with serviceable parts, within 250 FH after the borescope inspection performed in accordance with paragraph (b)(2)(i) of this AD. (iv) Thereafter, perform borescope inspections and ECIs or USIs, as applicable, of the blades for cracks and evidence of corrosion, alternating at intervals not to exceed 250 FH since the last inspection. Note 2: Alternating intervals means that if the last inspection was an ECI or a USI, the next inspection will be a borescope inspection. If the last inspection was a borescope inspection, the next 250 FH inspection will be an ECI or a USI as applicable. (v) Remove from service centrifugal compressor intake wheels found cracked and replace with serviceable parts. (c) For engines not modified to TU 197 but have been modified to TU 191 or TU 224 standard, that have been operated for more than 1,000 flight hours since the last inspection of the blades, do the following in accordance with Turbomeca Turmo IV SB 249 72 0100, Update 4, dated January 25, 2000: (1) Perform an initial ECI or USI, as applicable, of the blades for cracks, in accordance with paragraph 2.B.(3) of the SB, within the next 50 FH, or 6 months after the effective date of this AD, whichever occurs first. (2) Thereafter, inspect at intervals not to exceed 1,000 FH. (3) Remove from service centrifugal compressor intake wheels found cracked, and replace with a serviceable part. Alternative Methods of Compliance (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety maybe used if approved by the Manager, Engine Certification Office (ECO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO. Note 3: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO. Special Flight Permits (e) Special flight permits may be issued in accordance with 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 done. Documents That Have Been Incorporated by Reference (f) The inspections must be done in accordance with the following Turbomeca service bulletins: Document No. Pages Revision Date Turmo IV SB 249 72 0100 Total pages: 12 All Update No. 4 January 25, 2000. Turmo IV SB 249 72 0117 Total pages: 5All Original March 11, 2001. 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 Turbomeca, 40220 Tarnos, France; telephone (33) 05 59 64 40 00; fax (33) 05 59 64 60 80. Copies may be inspected at the FAA, New England Region, Office of the Regional 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. Note 4: The subject of this AD is addressed in Direction Generale de L'Aviation Civile airworthiness directive AD97-122(B), dated May 21, 1997. Effective Date (g) This amendment becomes effective on July 3, 2003.