AD 2020-24-08 Requires Replacement Of HPT Blades With Parts Eligible For Installation

The FAA is adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland Ltd & Co KG (Type Certificate Previously Held by Rolls-Royce plc) (RRD) RB211 Trent 768-60, 772-60, 772B-60 and 772C-60 model turbofan engines.

This AD requires replacement of high-pressure turbine (HPT) blades with parts eligible for installation before exceeding specified flight cycles since new. This AD was prompted by several reports from the manufacturer that HPT blades on RB211 Trent 700 model turbofan engines have been subject to high levels of corrosion
fatigue, leading to blade cracking and eventual release, resulting in an aborted take-off and in-flight shut-downs. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective January 4, 2021.

Supplementary Information: The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD No. 2018-0291, dated December 21, 2018 (referred to after this as “the MCAI”), to address the unsafe condition for the specified products. The MCAI states:

• HP turbine blades on a number of Trent 700 engines have been subject to high levels of corrosion fatigue, leading to blade cracking and eventual release. This has caused a number of aborted take-off and in-flight shut-down events. Sampling has identified that corrosion fatigue affects blades at varying rates, likely dependent on environmental, operational and individual blade conditions.
• This condition, if not corrected, could lead to blade failure and subsequent increased risk of high energy debris release, possibly resulting in damage to, and reduced control of, the aeroplane.
• To address this potential unsafe condition, RR issued the NMSB to provide instructions for removal from service of certain engines where a higher level of corrosion exposure is expected for the affected blades.
• For the reason described above, this [EASA] AD requires removal from service of certain engines, to be corrected in shop.

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-2020-1032.

FMI: www.regulations.gov