AD 2020-11-07 Addreses Report Of Non-Conforming Main Rotor (M/R) Hub Lead-Lag Bolts

The FAA is adopting a new airworthiness directive (AD) for MD Helicopters Inc., (MDHI) Model 369D, 369E, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. This AD was prompted by a report of non-conforming main rotor (M/R) hub lead-lag bolts (bolts).

This AD requires removing certain bolts from service. The FAA is issuing this AD to address the unsafe condition on these products.

This AD is effective June 30, 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 MDHI Model 369D, 369E, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, with certain serial-numbered bolts part number (P/N) 369D21220 installed.

The NPRM published in the Federal Register on February 7, 2020 (85 FR 7256). The NPRM was prompted by a report of non-conforming bolts. Certain serial-numbered bolts had an unauthorized repair of their cadmium plating performed between April 2004 and October 2018. Analysis has shown that these bolts have a lower fatigue life compared to bolts used during manufacturing batch testing. The NPRM proposed to require removing the affected bolts from service.

This condition, if not addressed, could result in loss of an M/R blade and subsequent loss of control of the helicopter. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov