AD 2021-26-06 Requires Visual Inspection Of The TGB Radial Gearshaft

The FAA is adopting a new airworthiness directive (AD) for certain General Electric Company (GE) GE90 model turbofan engines.

This AD was prompted by two separate in-flight shutdowns (IFSDs) resulting from failure of the transfer gearbox (TGB) radial bevel gear (TGB radial gearshaft). This AD requires visual inspection of the TGB radial gearshaft and, depending on the results of the inspection, replacement of the TGB radial gearshaft. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective February 15, 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 all GE GE90-76B, GE90-85B, GE90-90B, GE90-94B, GE90-110B1, and GE90-115B model turbofan engines with a certain TGB radial gearshaft installed. The NPRM published in the Federal Register on August 12, 2021 (86 FR 44321). The NPRM was prompted by notification of two separate IFSDs resulting from the failure of the TGB radial gearshaft. After further investigation, the manufacturer determined that rework on the TGB radial gearshaft teeth chamfers during manufacturing may have caused local burrs and micro-cracks which led to high-cycle fatigue failure. GE subsequently issued service information to provide instructions for a one-time visual inspection of the affected radial gearshafts for the presence of burrs or rework on TGB radial gearshaft teeth chamfers. In the NPRM, the FAA proposed to require visual inspection of the TGB radial gearshaft and, depending on the results of the inspection, replacement of the TGB radial gearshaft. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov