AD 2021-13-07 Requires Recalculating The Life Of Critical Parts

The FAA is adopting a new airworthiness directive (AD) for all GE Aviation Czech s.r.o. (GEAC) M601D-11, M601E-11, M601E-11A, M601E-11AS, M601E-11S, and M601F model turboprop engines.

This AD was prompted by the manufacturer finding errors in the Airworthiness Limitation Section (ALS) of the Engine Maintenance Manual (EMM), including errors in the formula to determine the equivalent flight cycles (FCs) of critical parts and errors with certain part numbers (P/Ns). The manufacturer also determined that the life limit of a certain compressor case is not listed in the ALS section of the applicable EMM. This AD requires recalculating the life of critical parts and, depending on the results of the recalculation, replacement of these critical parts. This AD also requires replacement of a certain compressor case. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective June 30, 2021.

Supplementary Information: The European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA Emergency AD 2021-0125-E, dated May 7, 2021 (referred to after this as “the MCAI”), to address an unsafe condition for the specified products. The MCAI states:

• Errors have been identified in the ALS section of the EMM [Engine Maintenance Manual], including errors in the formula to determine the equivalent flight cycles of critical parts, and certain part numbers. It was also determined that, inadvertently, certain M601E engines have a compressor case P/N M601-154.61 installed, the life limit of which is not listed in the ALS section of the applicable EMM.
• These conditions, if not corrected, may lead to operation of an engine beyond the life limit of one or more critical parts, possibly resulting in failure of the engine and consequent reduced control of the aeroplane.
• To address this potential unsafe conditions, GEAC issued [GEAC Alert Service Bulletin (ASB) ASB-M601D-72-00-00-0075, ASB-M601E-72-00-00-0106, ASBM601F-72-00-00-0057 and ASB-M601Z-72-00-00-0057 (issued as a single document)], providing instructions to recalculate the consumed life of certain critical parts, and [GEAC ASB-M601E-72-30-00-0105], providing instructions for certain M601E engines to replace the compressor case with an eligible part.
• For the reason described above, this [EASA] AD requires replacement of critical parts, the recalculated life of which exceeds the applicable life limit, and replacement of the compressor case on certain M601E engines.

You may obtain further information by examining the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0499.

FMI: www.regulations.gov