AD 2020-15-17 Prompted By Reports Of Inaccurate Main Gear Box (MGB) Indications

The FAA is adopting a new airworthiness directive (AD) for certain Sikorsky Aircraft Corporation Model S-76C helicopters.

This AD was prompted by reports of inaccurate main gear box (MGB) indications in flight. This AD requires updating the remote data acquisition unit (RDAU) software and re-identifying the RDAU and, for certain helicopters, updating the software of the display unit (DU) and re-identifying the DU. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective September 9, 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 certain Sikorsky Aircraft Corporation Model S-76C helicopters. The NPRM published in the Federal Register on April 6, 2020 (85 FR 19110). The NPRM was prompted by reports of inaccurate MGB indications in flight. The NPRM proposed to require updating the RDAU software and re-identifying the RDAU and, for certain helicopters, updating the software of the DU and re-identifying the DU.

The FAA is issuing this AD to address inaccurate MGB indications in flight, resulting in multiple erroneous values/annunciations on channel B, which could cause the flight crew to land immediately, and consequent possible loss of the helicopter, injury, or fatality.

FMI: www.regulations.gov