MBB-BK 117 All Series
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe
Flight Crew Landed As Precaution; Flight Crew Returned To Gate; General Maintenance Action
Aircraft
Crew was notified of scene flight. Pilot proceed[ed] through start up procedures. Upon taking off and over taxiway aircraft CAD displayed 'Actuator;' audio indication; pilot experienced minor uncommanded control inputs in the yaw axis and feedback in the pedals. Aircraft was still controllable. Pilot returned to landing area; landed without incident and proceeded with normal shutdown. Maintenance and dispatch notified of issue. Aircraft has exhibited condition in the past and is a noted maintenance concern about every 6 months. Has occurred in other aircraft of the same design. Unaware of corrective action that could be conducted. Track and conduct trend analysis; gather information and apply corrections via manufacturers guidance.
The reporter stated the uncommanded flight control input included a 45 degrees left turn followed by a 90 degrees right turn. The reporter knew the Actuator alert was MEL'able but because of the uncommanded maneuvers did not believe the flight should proceed. After landing; Maintenance discovered the tail rotor actuator malfunctioning. The actuator was replaced and the aircraft flew normally during the test flight. It seems that about every six months this component exhibits signs of a failure.
A BK-117 CAD alerted ACTUATOR with an audio indication along with minor uncommanded yaw and rudder pedal feedback during takeoff. The pilot landed without incident. This aircraft and other similar aircraft have displayed the same behavior.