AD 2020-23-08 Requires Limiting The Service Life Of The LPC Rotor Blades

The FAA is adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland Ltd & Co KG (RRD) Tay 611-8C model turbofan engines.

This AD was prompted by reports of low-pressure compressor (LPC) rotor blade retention lug failure. This AD requires limiting the service life of the LPC rotor blades based on the number of dry-film lubricant (DFL) reapplications. The FAA is issuing this AD to address the unsafe condition on these products. This  AD is effective December 18, 2020.

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 RRD Tay 611-8C model turbofan engines. The NPRM published in the Federal Register on May 6, 2019 (84 FR 19745). The NPRM was prompted by reports of LPC rotor blade retention lug failures. In the NPRM, the FAA proposed to require a determination of the number of DFL re-applications that have been applied to the LPC rotor blades and, depending on the number of DFL re-applications, replacement of LPC rotor blades. The FAA is  issuing this AD to address the unsafe condition on these products.

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD 2018-0055, dated March 12, 2018 (referred to after this as “the MCAI”), to address the unsafe condition on these products. The MCAI states:

The airworthiness limitations for the Tay 611-8C engines, which are approved by EASA, are currently defined and published in the ALS. Among others, the ALS contains limitation(s) applicable to the maximum number of Dry Film Lubrication (DFL) treatments applied on fan blade retention lugs. These instructions have been identified as mandatory for continued airworthiness. Failure to accomplish these instructions could result in an unsafe condition.

In addition to the ALS, RRD issued the NMSB to provide alternative methods to establish, in case this cannot be determined from the engine maintenance records, the number of DFL treatments that have been applied to an engine.

You may obtain further information by examining the MCAI in the AD docket at www.regulations.gov by searching for and locating Docket No. FAA-2019-0213.

FMI: www.regulations.gov