Airworthiness Directives; Bombardier Inc. Model Otter DHC-3 Airplanes

The FAA adopts a new airworthiness directive (AD) for certain Bombardier Inc. (formerly deHavilland Inc.) Model Otter DHC-3 airplanes that have turbine engines installed per one of three supplemental type certificates (STC). This AD prohibits you from operating any affected airplane with these engine and propeller configurations unless a new STC for an elevator servo-tab with a redundant control linkage is installed. This AD is the result of reports of the control rod to the elevator servo-tab system detaching from the elevator servo-tab, which caused the elevator servo-tab to flutter on airplanes with a turbine engine installed. We are issuing this AD to prevent a single failure of the elevator servo-tab system, which could cause severe tab flutter. This failure could lead to possible loss of control of the airplane.