Summary
The FAA proposes to adopt 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 proposed AD would prohibit 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 proposed AD also allows the option of future installations of one of three STCs if a new STC for an elevator servo-tab with a redundant control linkage is also installed. This proposed AD is the result of reports of the control rod to the servo trim tab system detaching from the servo trim tab, which caused the servo trim tab to flutter on airplanes with a turbine engine installed. We are issuing this proposed AD to prevent a single failure of the elevator servo trim tab system, which could cause severe elevator flutter. Such failurecould lead to possible loss of control of the airplane.