AD 2021-12-16 Prompted By A Report Of Increased Control Force In The Collective Axis

The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK117 C-2 and MBB-BK117 D-2 helicopters.

This AD was prompted by a report of increased control force in the collective axis. This AD requires repetitive visual inspections of the main rotor actuator (MRA), as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 3, 2021.

Supplementary Information: The EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2018-0283, dated December 20, 2018 (EASA AD 2018-0283), to correct an unsafe condition for AHD Model MBB-BK117 C-2 and MBB-BK117 D-2 helicopters. EASA later issued EASA AD 2020-0257, dated November 17, 2020 (EASA AD 2020-0257), to supersede EASA AD 2018-0283.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to AHD Model MBB-BK117 C-2 and MBB-BK117 D-2 helicopters. The NPRM published in the Federal Register on April 8, 2021 (86 FR 18221). The NPRM was prompted by a report of increased control force in the collective axis on an AHD Model EC135 helicopter. Subsequent inspections determined that a nut on a piston of the MRA had cracked and separated from the piston rod. Due to design similarity, Model MBB-BK117 C-2 and MBB-BK117 D-2 helicopters are also affected by this unsafe condition. The NPRM proposed to require repetitive visual inspections of the MRA as specified in EASA AD 2020-0257.

The FAA is issuing this AD to prevent failure of the MRA and subsequent loss of control of the helicopter. See the EASA AD for additional background information.

FMI: www.regulations.gov