AD 2021-26-04 Airworthiness Directives; Engine Alliance Turbofan Engines

This AD applies to all Engine Alliance (EA) GP7270 and GP7277 model turbofan engines.

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

(1) For EA GP7270 and GP7277 model turbofan engines with engine fan hub assembly part numbers (P/Ns) 5760221, 5760321, or 5760001, within 1,700 cycles since new, within 150 flight cycles (FCs) after October 9, 2019 (the effective date of AD 2019-18-08), within 330 FCs since an eddy current inspection (ECI) was performed using the Accomplishment Instructions of EA Turbojet Engines Alert Service Bulletin (ASB) EAGP7-A72-389, Revision No. 6, dated November 21, 2019, or earlier versions of that ASB, or before further flight, whichever occurs later: (i) For engine fan hub assemblies at the low-pressure compressor (LPC) module assembly level, perform an ECI of the engine fan hub blade slot bottom and blade slot front edge, and perform an ultrasonic test (UT) inspection of the fan hub rim area, using the Accomplishment Instructions, Part A—For Fan Hubs at LPC Module Assembly Level, paragraphs 1.B., 1.C., and 1.E., of EA Turbojet Engine ASB EAGP7-A72-389, Revision No. 7, dated October 8, 2021 (EAGP7-A72-389, Revision No. 7). (ii) For engine fan hub assemblies at the piece part level, perform an ECI of the engine fan hub blade slot bottom and blade slot front edge, and perform a UT inspection of the fan hub rim area, using the Accomplishment Instructions, Part B—For Fan Hubs at Piece Part Level, paragraphs 1.B., 1.C., and 1.E., of EAGP7-A72-389, Revision No. 7. (iii) For engine fan hub assemblies installed in an engine (on-wing or off-wing), perform an ECI of the engine fan hub blade slot bottom and blade slot front edge, and perform a UT inspection of the fan hub rim area, using the Accomplishment Instructions, Part C—For Fan Hubs Installed in an Engine, paragraphs 3.B., 3.C., and 3.E., of EAGP7-A72-389, Revision No. 7. (2) Thereafter, at intervals not exceeding 290 FCs since the previous ECI and UT inspection, repeat the ECI of the engine fan hub blade slot bottom, ECI of the blade slot front edge, and UT inspection of the fan hub rim area required by paragraphs (g)(1)(i) through (iii) of this AD. (3) If, during any ECI or UT inspection required by paragraphs (g)(1) through (g)(2) of this AD, a rejectable indication is found, before further flight, remove the engine fan hub assembly from service and replace with a part that is eligible for installation. (4) For all GP7270 and GP7277 model turbofan engines, after the effective date of this AD: (i) At the next disassembly of the engine fan hub blade lock assembly, visually inspect the fan hub fan blade lock groove area (also known as the fan hub lock ring contact area) for damage. (ii) At the next reassembly of the engine fan hub blade lock assembly, visually inspect the following areas of the engine fan hub for damage: (A) The fan hub scallop areas; (B) The fan hub bore area behind the balance flange; (C) The fan hub fan blade lock retention hooks; (D) The fan hub rim face; and (E) The clinch nut holes. (iii) After any reassembly of the fan hub blade lock assembly, before further flight, perform an independent inspection for damage of the areas of the engine fan hub identified in paragraph (g)(4)(ii) of this AD. (iv) Thereafter, repeat the inspections required by paragraphs (g)(4)(i) through (iii) of this AD at each disassembly and reassembly of the engine fan hub blade lock assembly, as applicable. (v) As an optional terminating action to the inspection and independent inspection requirements of paragraphs (g)(4)(i) through (iv) of this AD, insert the requirements for the visual inspections and independent inspections required by paragraphs (g)(4)(i) through (iv) as Required Inspection Items in the existing approved continuous airworthiness maintenance program for the airplane. (vi) If damage is found that exceeds serviceable limits during the inspections required by paragraphs (g)(4)(i) through (iv) of this AD, before further flight, remove the engine fan hub assembly from service and replace it with a part eligible for installation. (5) For GP7270 and GP7277 model turbofan engines with engine serial numbers P550101 through P550706, inclusive, within 200 FCs from August 1, 2020 or before further flight, whichever occurs later, remove the engine fan hub blade lock assembly, P/N 5700451, and replace it with a part eligible for installation. Note 1 to paragraph (g)(5): EA Turbojet Engines ASB EAGP7-A72-418, Revision No. 1, dated January 11, 2019, contains guidance on replacement of the engine fan hub blade lock assembly.

This AD was prompted by an uncontained failure of the engine fan hub. The FAA is issuing this AD to detect defects, damage, and cracks that could result in an uncontained failure of the engine fan hub assembly. The unsafe condition, if not addressed, could result in uncontained failure of the engine fan hub assembly, damage to the engine, and damage to the airplane.

This AD replaces AD 2019-18-08, Amendment 39-19735 (84 FR 49944, September 24, 2019).