Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters

This amendment adopts a new airworthiness directive (AD) for MD Helicopters, Inc. Model 600N helicopters that requires replacing the fuselage Station 75 control support bracket assembly (control support bracket), reducing the life limit, and revising the Limitations section of the applicable maintenance manual to state the reduced life limits on certain serial-numbered helicopters. This amendment is prompted by information received from the manufacturer indicating that the fatigue life of the control support bracket is shorter than the original analysis indicated. The actions specified by this AD are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter.