Type Certificate Previously Held by WALTER Engines a.s., Walter a.s., and MOTORLET a.s. Turboprop Engines

The FAA is adopting a new airworthiness directive (AD) for certain 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 absence of life limits for propeller shaft part number (P/N) M601-6081.6 in the airworthiness limitations section (ALS) of the applicable GEAC M601 Engine Shop Manual. This AD was also prompted by a report that operators may not have been provided with enough data to determine the accumulated life of certain propeller shafts. For M601F model turboprop engines, this AD requires removal and replacement of the propeller shaft before the propeller shaft accumulates 12,000 flight hours (FHs) since first installation on an engine, or before accumulating 350 FHs after the effective date of this AD, whichever occurs later, with a part eligible for installation. For M601D-11, M601E-11, M601E-11A, M601E-11AS, and M601E11S model turboprop engines, this AD requires calculation of the accumulated life of the propeller shaft and, depending on the number of accumulated FHs removal and replacement of the propeller shaft with a part eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 18, 2022.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain GEAC M601D-11, M601E-11, M601E-11A, M601E-11AS, M601E-11S, and M601F model turboprop engines. The NPRM published in the Federal Register on April 01, 2022 (87 FR 19029). The NPRM was prompted by the absence of life limits for propeller shaft P/N M601-6081.6 in the ALS of the applicable GEAC M601 Engine Shop Manual. The NPRM was also prompted by a report that operators may not have been provided with enough data to determine the accumulated life of certain propeller shafts.

For M601F model turboprop engines, the NPRM proposed to require removal and replacement of the propeller shaft with a part eligible for installation before the propeller shaft accumulates 12,000 FHs since first installation on an engine, or before accumulating 350 FHs after the effective date of this AD, whichever occurs later. For M601D11, M601E-11, M601E-11A, M601E-11AS, and M601E-11S model turboprop engines, the NPRM proposed to require calculation of the accumulated life of the propeller shaft and, depending on the number of accumulated FHs, removal and replacement of the propeller shaft with a part eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.  The European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2021-0154, dated July 1, 2021 (referred to after this as “the MCAI”), to address the unsafe condition on these products.

The MCAI states:

• It has been determined that the life limit for the propeller shaft P/N M601-6081.6 is not published in the applicable ALS for M601 engines. In addition, it has also been reported that some data, which can be used to determine the accumulated life of certain propeller shafts, may have not been provided to operators, so the propeller shaft life limit may not have been implemented correctly.  
• These conditions, if not corrected, may lead to failure of a propeller shaft, possibly resulting in detachment of the propeller and consequent damage to the engine and/or the aircraft, and reduced control of the aeroplane.  
• To address this potential unsafe condition, GEAC issued the original issue of the ASB, providing applicable instructions, and EASA issued AD 2021-0052 to require implementation of the applicable life limit and replacing each propeller shaft with a serviceable propeller shaft.
• Since that [EASA] AD was issued, additional data, which can be used to determine the accumulated life of certain propeller shafts, and to support an extended compliance time for Group 1 engines, has been made available; GEAC revised accordingly the ASB (now at revision 02).  
• For the reasons described above, this [EASA] AD partially retains the requirements of EASA AD 2021-0052, which is superseded, introducing updated affected population and different compliance times.   

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-2022-0385.

FMI: www.regulations.gov