AD 2021-22-19 Airworthiness Directives; Pratt & Whitney Turbofan Engines

This AD applies to Pratt & Whitney (P&W) JT8D-209, JT8D-217, JT8D-217A, JT8D-217C, and JT8D-219 model turbofan engines.

Comply with this AD within the compliance times specified, unless already done.

(1) For JT8D-209, JT8D-217, and JT8D-217A model turbofan engines, within the compliance times specified in the Accomplishment Instructions, Part 1: JT8D-209, -217, -217A Engines (Part 1), paragraph 1.A., of P&W Alert Service Bulletin No. JT8D A6224, Revision No. 7, dated August 26, 2019 (the ASB), perform an initial torque inspection for shroud notch wear of the 3rd-stage LPT blades using the procedures in Part 1, paragraph 1, of the ASB. (i) Thereafter, within the applicable reinspection interval specified in Table 1—Reinspection Interval for all 3rd Stage Blades, of the ASB, repeat the torque inspection for shroud notch wear required by paragraph (g)(1) of this AD. (ii) If the results of the torque inspection required by paragraphs (g)(1) or (g)(1)(i) of this AD meet the criteria for engine removal specified in Table 1—Reinspection Interval for all 3rd Stage Blades, of the ASB, perform piece-part inspections in accordance with the Instructions for Continued Airworthiness (ICA) on all 3rd-stage LPT blades before exceeding 20 hours time-in-service (TIS) since the last torque inspection. (2) For JT8D-209, JT8D-217, and JT8D-217A model turbofan engines, within the compliance times specified in Table A or Table B, of the ASB, as applicable, perform an initial torque inspection for shroud notch wear of the 4th-stage LPT blades using the procedures in Part 1, paragraph 1, of the ASB. Wherever the ASB refers to “Revision 7 Release Date” and “At SB Release Date,” use the effective date of this AD. (i) For engines in which the last inspection prior to the effective date of this AD had a torque inspection result of less than 15 LB-IN on any 4th-stage LPT blade, perform piece-part inspections in accordance with the ICA on all 3rd-stage and 4th-stage LPT blades within 20 hours TIS after the effective date of this AD. (ii) Thereafter, within the applicable reinspection interval specified in Table 2—Reinspection Interval for all 4th Stage Blades, of the ASB, repeat the torque inspection for shroud notch wear required by paragraph (g)(2) of this AD. (iii) If the results of the torque inspection required by paragraphs (g)(2) or (g)(2)(ii) of this AD meet the criteria for engine removal specified in Table 2—Reinspection Interval for all 4th Stage Blades, of the ASB, perform piece-part inspections in accordance with the ICA on all 3rd-stage and 4th-stage LPT blades before exceeding 20 hours TIS since the last torque inspection. (3) For JT8D-217C and JT8D-219 model turbofan engines, within the compliance times specified in Table A or Table B, of the ASB, as applicable, perform an initial torque inspection for shroud notch wear of the 4th-stage LPT blades using the procedures in the Accomplishment Instructions, Part 2: JT8D-217C, -219 Engines (Part 2), paragraph 1, of the ASB. Wherever the ASB refers to “Revision 7 Release Date” and “At SB Release Date,” use the effective date of this AD. (i) For engines in which the last inspection prior to the effective date of this AD had a torque inspection result of less than 15 LB-IN on any 4th-stage LPT blade, perform piece-part inspections in accordance with the ICA on all 3rd-stage and 4th-stage LPT blades within 20 hours TIS after the effective date of this AD. (ii) Thereafter, within the reinspection interval specified in Table 3—Reinspection Interval for all 4th Stage Blades, of the ASB, repeat the torque inspection for shroud notch wear required by paragraph (g)(3) of this AD. (iii) If the results of the torque inspection required by paragraph (g)(3) and (g)(3)(ii) of this AD meet the criteria for engine removal specified in Table 3—Reinspection Interval for all 4th Stage Blades, of the ASB, perform piece-part inspections in accordance with the ICA on all 3rd-stage and 4th-stage LPT blades before exceeding 20 hours TIS since the last torque inspection. (4) At the first engine shop visit after January 1, 2023, or prior to accumulating 5,000 TIS on the 3rd-stage and 4th-stage LPT blades, whichever occurs later, but not to exceed 6 years after the effective date of the AD, replace the 3rd-stage and 4th-stage LPT blades with parts eligible for installation. (5) Thereafter, prior to accumulating 5,000 hours TIS on the 3rd-stage and 4th-stage LPT blades since their last replacement, replace the 3rd-stage and 4th-stage LPT blades with parts eligible for installation. (6) After every replacement of the 3rd-stage or 4th-stage LPT blades, perform initial and repetitive torque inspections of the 3rd-stage or 4th-stage LPT blades using, as applicable, the accomplishment instructions and compliance times in Part 1, paragraph 1, or Part 2, paragraph 1, of the ASB. (i) If the results of the torque inspection required by paragraph (g)(6) of this AD meet the criteria for engine removal specified in Table 1, 2 or 3, of the ASB, as applicable, perform piece-part inspections in accordance with the ICA on all 3rd-stage and 4th-stage LPT blades before exceeding 20 hours TIS since the last torque inspection. (ii) [Reserved] (7) The initial inspection or the reinspection interval should not be reset unless the blades are refurbished. Whenever a used blade is reinstalled in a rotor, the previous used time should be subtracted from the initial inspection threshold. (8) Whenever a refurbished or used blade is intermixed with zero hours time-since-new (TSN) blades in a rotor, use the lowest initial inspection threshold that is applicable. (9) At the next accessibility to the LPT-to-exhaust case bolts and nuts after the effective date of this AD, do the following: (i) Replace the bolts with part number (P/N) MS9557-26 bolts; (ii) Replace the nuts with P/N 375095 nuts or P/N 490270 nuts; and (iii) Install crushable sleeve spacers, P/N 822903, under the head of the bolts. Note 1 to paragraph (g): Guidance on replacing the 3rd-stage and 4th-stage LPT blades can be found in P&W ASB JT8D A6507, dated November 2, 2020. Note 2 to paragraph (g): Guidance on replacing the LPT-to-exhaust case bolts and nuts and installing the crushable sleeve spacers can be found in P&W ASB No. JT8D A6494, Revision No. 1, dated January 26, 2010.

This AD was prompted by a report of an MD-82 airplane, equipped with a JT8D-217C model turbofan engine, experiencing an engine surge that resulted in the fracture of the low-pressure turbine (LPT) blade and uncontained release of the LPT blade. Five prior uncontained LPT blade failures were also reported on affected model turbofan engines. The FAA is issuing this AD to prevent LPT blade fracture and uncontained release of the LPT blade. The unsafe condition, if not addressed, could result in uncontained engine debris, damage to the engine, and damage to the aircraft.

This AD replaces AD 2011-07-02, Amendment 39-16639 (76 FR 16526, March 24, 2011).