Airworthiness Directives; Airbus Helicopters Deutschland GmbH (Previously Eurocopter Deutschland GmbH) Helicopters

We propose to adopt a new airworthiness directive (AD) for Airbus Helicopters Deutschland GmbH (AHD) (previously Eurocopter Deutschland GmbH) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, C-1, and C- 2 helicopters. This proposed AD would require an initial and recurring inspection of the N2 control arm and, depending on the outcome of the inspection, repairing or replacing the N2 control arm. This proposed AD is prompted by a report of a heavily corroded and broken N2 control arm. The proposed actions are intended to detect corrosion, a crack, or a scratch in the N2 control arm, which could lead to failure of the N2 control arm, a drop in rotor speed, and subsequent loss of control of the helicopter.