AD Issued. Root Cause still out There.
Excerpts Only, Use Link for full texts.
2015-27-01. GE90-76B, -77B, -85B, -90B, and -94B engines with high-pressure compressor (HPC) stage 8-10 spool, part number 1694M80G04, installed. SUMMARY: This AD requires performing an eddy current inspection (ECI) or ultrasonic inspection (USI) of the high-pressure compressor (HPC) stage 8-10 spool and removing from service those parts that fail inspection. This AD was prompted by an uncontained failure of the HPC stage 8-10 spool, leading to an airplane fire. Effective January 27, 2016. Compliance by; (1) Perform an eddy current inspection or ultrasonic inspection of the stage 8 aft web upper face of the HPC stage 8-10 spool for cracks as follows: (i) For HPC stage 8-10 spools with serial number (S/N) GWNHC086 or GWNHB875, inspect within 150 cycles-in-service (CIS), after the effective date of this AD. (ii) For HPC stage 8-10 spools with S/N GWNHC154, GWNHA455, GWNHC153, or GWNHB516, inspect within 300 CIS, after the effective date of this AD. (2) Remove from service any HPC stage 8-10 spool that fails the inspection required by paragraph (e)(1) of this AD and replace the spool with a spool eligible for installation. Discussion. We received a report of an HPC stage 8-10 spool uncontained failure resulting in an airplane fire. Ongoing investigations have determined that a crack initiated in the stage 8 aft web upper face of the HPC 8-10 spool and propagated until spool rupture. The root cause of the crack initiation is not yet known. Costs of Compliance. We estimate that this AD affects 1 engine installed on an airplane of U.S. registry. We also estimate that it will take about 7 hours per engine to comply with this AD. The average labor rate is $85 per hour. Required parts cost about $780,000 per engine. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $780,595. Link > http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/70e7b9e69301df4186257f380054ed8a/$FILE/2015-27-01.pdf -----------------------------
Prior ADs With mentions of HPC spools web cracks.
2009-07-03 – 80 series, 2002-25-08 – 45/50, and – 80s, 99-24-15 - 50 and -80 series,
For Full AD and Details, Query By AD number at FAA’s AD Query website; Link >
Airworthiness Directives