AD 2020-15-07 Requires Replacement Of The Low-Pressure Turbine (Lpt) Stage 1 Disk

The FAA is adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland Ltd & Co KG RB211-524G2-19, RB211-524G2-T-19, RB211-524G3-19, RB211-524G3-T-19, RB211-524H2-19, RB211-524H2-T-19, RB211-524H-36 and RB211-524H-T-36 model turbofan engines.

This AD requires replacement of the low-pressure turbine (LPT) stage 1 disk before it reaches its new Declared Safe Cycle Limit (DSCL) or within 25 flight cycles after the effective date of this AD, whichever occurs later. This AD was prompted by a determination by the manufacturer that the affected LPT stage 1 disks cannot operate until their former published life limit. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 4, 2020.

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 AD No. 2020-0059, dated March 17, 2020 (referred to after this as “the MCAI”), to address an unsafe condition for the specified products.

The MCAI states:

• A review of operational flight data revealed that some RB211-524 engines may have been operated beyond the currently valid datum flight profile (FP) published in the applicable Aircraft Maintenance Manuals. The purpose of the datum FPs is to establish the operational limits (life limits) within which the corresponding critical parts are allowed to remain installed. In addition, as this FP exceedance was investigated, it was realised that the current life limits of certain P/N corresponding to reworked LPT Stage 1 discs (time since new, or since entry into service following rework) could no longer be supported.
• This condition, if not corrected, could lead to disc failure, possibly resulting in engine in-flight shut-down and high energy debris release, with consequent damage to, and reduced control of, the aeroplane.
• Prompted by these findings, Rolls-Royce published worldwide (WW) communication, reference WW11575-1, which  identified certain parts, some of which were believed to have exceeded their respective safe cyclic life, to collect information in relation to the history of affected parts and to inform current operators and owners of the affected parts of an imminent life reduction. Rolls-Royce also published the NMSB, providing instructions for timely removal from service of the affected parts.

For the reasons described above, this AD requires removal from service of the affected parts. This AD also prohibits (re)installation of affected parts that have exceeded the new reduced limits.

FMI: www.regulations.gov