AD 2021-26-16 Prompted By Multiple Reports Of Failure Of The Main Driveshaft

The FAA is adopting a new airworthiness directive (AD) for certain type certificated Model UH-1H restricted category helicopters.

This AD was prompted by multiple reports of failure of the main driveshaft. This AD requires establishing a limit to replace certain main driveshafts, and a one-time and repetitive inspections of the main driveshafts. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective February 25, 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 restricted category Model UH-1H helicopters with KAflex main driveshaft part number (P/N) SKCP2180-1, SKCP2281-1, SKCP2281-1R, or SKCP2281-103 installed. The NPRM published in the Federal Register on March 26, 2021 (86 FR 16126). The NPRM was prompted by multiple reports of failure of a main driveshaft. In the NPRM, the FAA proposed to require establishing a life limit for those part-numbered main driveshafts, removing and inspecting the main driveshaft, inspecting the alignment of the main driveshaft installation, and repetitive inspections of the main driveshaft.

As an optional terminating action, the NPRM proposed to allow the installation of a certain part-numbered main driveshaft not affected by this unsafe condition. This condition, if not addressed, could result in loss of engine power to the transmission and subsequent loss of control of the helicopter.

FMI: www.regulations.gov