Airworthiness Directive · Amendment 39-18700 · Engine Alliance Turbofan Engines
Engine Alliance Turbofan Engines
This AD applies to all Engine Alliance GP7270 and GP7277 turbofan engines with a high-pressure turbine (HPT) stage 2 nozzle segment, part number (P/N) 2101M24G01, 2101M24G02, 2101M24G03, 2101M24G04, 2101M24G05, or 2101M24G06, installed.
We are superseding airworthiness directive (AD) 2013-02-06 for all Engine Alliance (EA) GP7270 and GP7277 turbofan engines with certain part number (P/N) high-pressure turbine (HPT) stage 2 nozzle segments installed. AD 2013-02-06 required initial and repetitive borescope inspections (BSI) and removal from service of these nozzles before further flight if one or more burn holes were detected in any HPT stage 2 nozzle segment. AD 2013-02-06 also required removal from service of these HPT stage 2 nozzle segments at the next engine shop visit. This AD requires the same inspections as AD-2013-02-06, requires removal of affected HPT stage 2 nozzles at next piece-part exposure, and adds certain P/Ns to the applicability. This AD was prompted by another report of inadequate cooling of the HPT stage 1 shroud and stage 2 nozzle, leading to damage to the HPT stage 2 nozzle, burn- through of the turbine case, and in-flight shutdown. We are issuing this AD to prevent HPT stage 2 nozzle failure, uncontrolled fire, in- flight shutdown, and damage to the airplane.
(1) Perform a 360 degree borescope inspection of the HPT stage 1 shroud and stage 2 nozzle as follows:
(i) For engines with nozzles installed at a shop visit that did not include full engine overhaul, borescope inspect the HPT stage 1 shroud and stage 2 nozzle as follows:
(A) If the nozzle has fewer than 1,050 cycles-since-new (CSN) or cycles-since-repair (CSR) on the effective date of this AD, before the nozzle has accumulated 1,100 CSN or CSR.
(B) If the nozzle has 1,050 or more CSN or CSR on the effective date of this AD, within the next 50 cycles.
(ii) For all other engines, borescope inspect the HPT stage 1 shroud and HPT stage 2 nozzle as follows:
(A) If the nozzle has fewer than 1,450 CSN or CSR on the effective date of this AD, before the nozzle has accumulated 1,500 CSN or CSR.
(B) If the nozzle has 1,450 or more CSN or CSR on the effective date of this AD, within the next 50 cycles.
(iii) Thereafter, repetitively borescope inspect the HPT stage 1 shroud and stage 2 nozzle as follows:
(A) For engines with HPT stage 2 nozzle segments, P/N 2101M24G01, 2101M24G02, or 2101M24G03, within every 150 additional cycles-in-service (CIS).
(B) For engines with HPT stage 2 nozzle segments, P/N 2101M24G04, 2101M24G05, or 2101M24G06, within every 300 additional CIS.
(2) If any burn holes are detected through the surface of the nozzle or if the shroud is distorted radially inward with evidence of blade tip rubs, remove the HPT stage 1 shroud and HPT stage 2 nozzle from service before further flight.
Replace HPT stage 2 nozzle segments, P/N 2101M24G01, 2101M24G02, 2101M24G03, 2101M24G04, 2101M24G05, and 2101M24G06, at the next piece-part exposure, with parts eligible for installation.
For the purpose of this AD, piece-part exposure is when the HPT stage 2 nozzle is removed from the engine and completely disassembled.
