CJ610 / CF700 Engine Topic 01-2011 - Revised Inspection Procedures for Compressor Corrosion Pits

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CJ610 / CF700 Engine Topic 01-2011 - Revised Inspection Procedures for Compressor Corrosion Pits

CJ610 / CF700 Engine Topic 01-2011
Date: 28 October 2011
To: All GE-CJ610 and CF700 Operators, Service Centers, and Overhaul Shops
Subject: Revised Inspection Procedures for Compressor Corrosion Pits
The purpose of this Engine Topic is to advise all operators of pending changes to the maintenance and overhaul manuals regarding inspection for corrosion pits in the compressor disks and the subsequent actions to take following their discovery. These recommendations are being made based on CJ610/CF700 inspection data, as well as significant compressor disk cracking experienced in the J85 fleet, and the resulting investigative conclusions.
GE Aviation determined that corrosion pitting in AM355 compressor disks is a function of the base material and creates an initiation point for crack formation in the compressor’s critical life limited areas. In response, revised inspections to find this type of pitting are being incorporated and if a pit is found the part will be removed from service. 
The CJ610 and CF700 overhaul manuals state that cracks found in the compressor disks are neither repairable nor serviceable. To ensure the continued safety of the CJ610 and CF700 fleets, GE Aviation is revising the overhaul manuals to mandate that corrosion pits of any size, found during piece part inspection of the compressor disks, result in replacement of the pitted part. Since the time between piece part exposures can be extensive, this new procedure will help preclude the formation of cracks from known initiation points during these intervals.
GE Aviation is also establishing engine maintenance programs in Chapter 5-21 of the CJ610 and CF700 maintenance manuals. The programs will identify parts that require mandatory inspections to be accomplished at each piece-part exposure. Specifically it will call out the AM355 compressor disks to ensure that crack initiating corrosion pits are identified and the associated parts removed.
GE Aviation continues to request that operators and shops send us retired and/or unserviceable hardware. CJ610 and CF700 compressor disks and spacers will be forwarded to the GE Lynn materials lab for metallurgical analysis of inspection findings. Please provide the following information with all returned pieces:
a.       Cycles accumulated on each part.
b.       Date of installation and removal from engine or retirement.
c.        If applicable, the conditions of storage, e.g. indoors, open shelf, sealed packaging, etc.
d.       If available, date and findings of most recent FPI (or highest form of inspection).

Please use the following address, and contact the undersigned in advance of shipping for a GE tracking number. When sending parts to GE, please indicate whether the parts must be returned or if GE may scrap them locally.
GE Military Hardware Returns
c/o Crescent
Attn: John Marshall (781-594-5336)
9817 Crescent Park Dr.
West Chester, OH 45069
GE Aviation also welcomes as much information as possible from current and past compressor rotor overhauls. Please include visual and FPI inspection results as well as anecdotal experience regarding compressor hardware findings. The Business Jet Operations Center can be contacted at the numbers below to coordinate electronic delivery, hard copy delivery, or verbal passage of this information.
USA toll free: 877-456-JETS or 877-456-5387
International: 513-552-JETS or 513-552-5387
Email: [email protected]
Akhtar Naqvi
Customer Support Program Manager
Phone: 513-552-4369
Fax: 513-552-4369
Email [email protected]

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