AD FAA-2006-26721

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2006-26-51, which was sent previously to all known U.S. owners and operators of Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 C-2 helicopters by individual letters. This AD requires, before further flight, marking the position of the tail rotor control lever dynamic weights (weights), removing the split pins and the weights, and visually inspecting and replacing, if necessary, the tail rotor control lever before further flight. This AD also requires, within 10 hours time-in-service (TIS), and thereafter at intervals not to exceed 25 hours TIS, repeating the visual inspection of the tail rotor control lever and replacing any unairworthy tail rotor control lever with an airworthy tail rotor control lever before further flight. Also required is reassembling the tail rotor control lever by following the appropriate maintenance instruction. This amendment is prompted by an in-flight incident in which the threaded portion of the tail rotor control lever containing a dynamic weight broke off leading to severe vibrations. The actions specified by this AD are intended to prevent separation of the weights in flight, severe vibration, and subsequent loss of control of the helicopter.