Dimension Anomalies Found That Could Affect Cooling Airflow

The FAA has issued a revised Special Airworthiness Information Bulletin (SAIB) to inform owners, operators, and certificated repair facilities of all CFM International CFM56-5, -5A1, -5A1/F, -5A3, -5A4, -5A4/F, -5A5, -5A5/F turbofan engines that non-type certificate holder-repaired low pressure turbine (LPT), stage 1 nozzle guide vanes (NGV), supplied by Chromalloy Gas Turbine, LLC (Chromalloy), are being removed from service due to dimensional anomalies that can affect the cooling airflow to the turbine.

These engines are installed on, but not limited to, Airbus Industries A319 and A320 airplanes. The airworthiness concern is not an unsafe condition that would warrant airworthiness directive action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.We have revised this SAIB to reference updated Chromalloy Service Bulletin (SB) CGT SB 72-047, Revision 1, dated November 26, 2013. The SB was updated to remove a Chromalloy repair part number from service.

The Chromalloy LPT NGV repair increases the dimensional variation in the features that provide the primary cooling air to the turbine. The potential effects of reduced cooling on the turbine include shortfalls in the service life of turbine engine parts. Chromalloy has issued SB CGT SB 72-047, Revision 1, dated November 26, 2013, to replace the Chromalloy-repaired CFM56-5A stage 1 LPT NGV segments. The Chromalloy-repaired LPT NGV removal program is based on the likelihood of an unsafe condition developing in affected CFM56-5A engines.

The FAA recommends that all owners, operators, and certificated repair facilities of affected engines follow the instructions in SB CGT SB 72-047 Revision 1, dated November 26, 2013, to remove the affected parts. Incorporating the SB into your shop procedures soon will decrease the likelihood of shortfalls in the service life of turbine parts.

FMI: SAIB