Airworthiness Directive · Amendment 39-19699 · Turbine engine compressor section
Engine Alliance Turbofan Engines
This AD applies to all Engine Alliance (EA) GP7270, GP7272, and GP7277 model turbofan engines.
The FAA is superseding Airworthiness Directive (AD) 2018-22-07 for all Engine Alliance (EA) GP7270, GP7272, and GP7277 model turbofan engines. AD 2018-22-07 required inspection of the stage 6 seal ring for correct installation and inspection of the high-pressure compressor (HPC) stages 2-5 spool for cracks and, depending on the results of the inspections, replacement of the HPC stages 2-5 spool with a part eligible for installation. This AD requires the same inspections but reduces the inspection interval and adds a repetitive inspection and a mandatory terminating action. This AD was prompted by a shop finding of axial cracks in the interstage 5-6 seal teeth of the HPC stages 2-5 spool spacer arm due to an incorrectly installed stage 6 seal ring. The FAA is issuing this AD to address the unsafe condition on these products.
(1) For all HPC stages 2-5 spools, perform an initial borescope inspection (BSI) of the HPC stage 6 seal ring position:
(i) Borescope inspect the HPC stage 6 seal ring location in accordance with the Accomplishment Instructions, paragraph 1.F, of EA Alert Service Bulletin (ASB) EAGP7-A72-395, Revision No. 3, dated June 3, 2019, and within the compliance times specified in Table 1 to paragraph (g)(1) of this AD or within 230 engine cycles after the effective date of this AD, whichever occurs first. If the HPC stage 6 seal ring is installed incorrectly, remove the HPC stages 2-5 spool from service within 50 engine cycles and replace with a part eligible for installation, and correct the location of the stage 6 seal ring.
(ii) Borescope inspect the HPC interstage 5-6 seal tooth forward and aft face for cracks and missing coating in accordance with the Accomplishment Instructions, paragraphs 2.C and 2.E, of EA ASB EAGP7-A72-395, Revision No. 3, dated June 3, 2019, and within the compliance times specified in Table 1 to paragraph (g)(1) of this AD or within 230 engine cycles after the effective date of this AD, whichever occurs first.
(A) If the coating is missing on the HPC interstage 5-6 seal tooth forward or aft face, thereafter, repeat the BSI required by paragraph (g)(1)(ii) of this AD for cracks within every 150 engine cycles since you performed the last BSI.
(B) If cracks are found in the HPC interstage 5-6 seal tooth forward or aft face, remove the HPC stages 2-5 spool from service and replace with a part eligible for installation before further flight.
| Cycles since new (CSN) on HPC stages 2-5 spool as of January 11, 2019 (the effective date of AD 2018-22-07) | Complete the inspection |
|---|---|
| 2,499 or less | Within 900 engine cycles after January 11, 2019, but not to exceed 2,850 CSN. |
| 2,500 to 3,499 | Within 350 engine cycles after January 11, 2019, but not to exceed 3,600 CSN. |
| 3,500 or more | Within 100 engine cycles after January 11, 2019. |
(2) For HPC stages 2-5 spools listed in Table 1 of Appendix A of EA SB EAGP7-72-413, dated February 4, 2019, perform the following repetitive on-wing inspections:
(i) Borescope inspect the HPC interstage 5-6 seal tooth forward and aft face for cracks and missing coating in accordance with the Accomplishment Instructions, paragraphs 1.E. and 1.G., of EA SB EAGP7-72-413, dated February 4, 2019, within 300 engine cycles after completion of the initial inspection required by paragraph (g)(1)(ii) of this AD. If the engine has already accumulated more than 200 engine cycles since the inspection required by paragraph (g)(1)(ii) of this AD, perform this BSI of the HPC interstage 5-6 seal tooth forward and aft face within the next 100 engine cycles after the effective date of this AD, but before exceeding 500 engine cycles since the last inspection required by paragraph (g)(1)(ii) of this AD.
(A) If the coating is found missing on the HPC interstage 5-6 seal tooth forward or aft face during the BSI, thereafter, repeat the BSI required by paragraph (g)(2)(i) of this AD for cracks within every 150 engine cycles since last BSI required by paragraph (g)(2)(i).
(B) If cracks are found in the HPC interstage 5-6 seal tooth forward or aft face during the BSI, remove the HPC stages 2-5 spool from service and replace with a part eligible for installation before further flight.
(ii) Thereafter, repeat the BSI required by paragraph (g)(2)(i) of this AD at intervals not exceeding 300 engine cycles since the last BSI.
As a terminating action to the on-wing repetitive BSI required by paragraph (g)(2) of this AD, at the next engine shop visit after the effective date of this AD, perform the following inspections and, if necessary, replacement of any HPC stages 2-5 spools listed in Table 1 of Appendix A of EA SB EAGP7-72-413, dated February 4, 2019.
(1) Visually inspect for the location of the HPC stage 6 seal ring in accordance with the Accomplishment Instructions, paragraph 1, of EA SB EAGP7-72-398, dated February 4, 2019. If the seal ring is found to be installed incorrectly, remove the HPC stages 2-5 spool and the HPC stage 6 seal ring from service and replace with parts eligible for installation.
(2) Perform an eddy current inspection (ECI) of the HPC interstage 5-6 seal teeth on the HPC stages 2-5 spool in accordance with Accomplishment Instructions, paragraph 2, of EA SB EAGP7-72-398, dated February 4, 2019. If there are ECI indications, as defined in paragraph 2 of EA SB EAGP7-72-398, remove the HPC stages 2-5 spool from service and replace with a part eligible for installation.
(3) Dimensionally inspect the diameter of the middle tooth of the HPC interstage 5-6 seal teeth on eight equally spaced points of the HPC stages 2-5 spool in accordance with the Accomplishment Instructions, paragraph 3, of EA SB EAGP7-72-398, dated February 4, 2019. If the average diameter is larger than the “expected diameter,” as defined in the Accomplishment Instructions, Figure 4 and Figure 5, of EA SB EAGP7-72-398, dated February 4, 2019, remove the HPC stages 2-5 spool from service and replace with a part eligible for installation.
For the purpose of this AD, an “engine shop visit” is the induction of an engine into the shop for maintenance involving the separation of pairs of major mating engine case flanges, except for the following situations, which do not constitute an engine shop visit:
(1) Separation of engine flanges solely for the purposes of transportation of the engine without subsequent maintenance.
(2) Separation of engine flanges solely for the purpose of replacing the fan or propulsor without subsequent engine maintenance.
The reporting requirements in the Accomplishment Instructions, paragraphs 1 and 2 of EA SB EAGP7-72-398, dated February 4, 2019, are not required by this AD.
