An air turbine starter for starting an engine, comprising a housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet for communicating a flow of gas there through. A turbine member is journaled within the housing and disposed within the flow path for rotatably extracting mechanical power from the flow of gas and a gear train is drivingly coupled with the turbine member. A drive shaft is operably coupled with the gear train, and a decoupler is selectively coupled to the drive shaft for decoupling the air turbine starter from the engine.