Airworthiness Directive · Amendment 39-18658 · General Electric Company Turbofan Engines
General Electric Company Turbofan Engines
This AD applies to General Electric Company (GE) GE90-76B, GE90-77B, GE90-85B, GE90-90B, and GE90-94B turbofan engines with a high-pressure compressor (HPC) stage 8-10 spool, part numbers 1694M80G04, 1844M90G01, or 1844M90G02, installed.
We are adopting a new airworthiness directive (AD) for all General Electric Company (GE) GE90-76B, GE90-77B, GE90-85B, GE90-90B, and GE90-94B turbofan engines with high-pressure compressor (HPC) stage 8-10 spool, part numbers (P/Ns) 1694M80G04, 1844M90G01, or 1844M90G02, installed. This AD was prompted by reports of cracks found on the seal teeth of the HPC stage 8-10 spool. This AD requires eddy current inspections (ECIs) or fluorescent penetrant inspections (FPIs) of the HPC stage 8-10 spool seal teeth and removing from service those parts that fail inspection. We are issuing this AD to prevent failure of the HPC stage 8-10 spool, uncontained rotor release, damage to the engine, and damage to the airplane.
(1) Perform an eddy current inspection (ECI) or fluorescent penetrant inspection (FPI) of the seal teeth of the HPC stage 8-10 spool as follows:
(i) For HPC stage 8-10 spools with fewer than 11,000 cycles since new (CSN) on the effective day of this AD, inspect at the next shop visit after reaching 6,000 CSN, not to exceed 12,500 CSN.
(ii) For HPC stage 8-10 spools with 11,000 CSN or more on the effective day of this AD, inspect within the next 1,500 cycles in service.
(iii) Thereafter, inspect the seal teeth of the HPC stage 8-10 spool at each shop visit.
(2) Remove from service any HPC stage 8-10 spool that fails the ECI or FPI required by paragraph (e)(1) of this AD and replace with a part eligible for installation.
(3) Guidance on performing the ECI and the FPI can be found in GE Service Bulletins (SBs) SB 72-1141 R00, dated December 2, 2015 and SB 72-1142 R00, dated November 30, 2015.
For the purpose of this AD, an engine shop visit is the induction of an engine into the shop for maintenance during which the compressor discharge pressure seal face is exposed.
