What is the purpose of a starter motor in an aircraft?

The starter motor in an aircraft serves the critical function of providing the initial rotational force necessary for engine ignition. When the starter motor is engaged, it turns the engine's crankshaft, which initiates the processes within the engine that lead to combustion and ultimately engine start-up. This initial spin is crucial because it allows for the proper functioning of the ignition system and fuel system to create a combustible mixture that can sustain engine operation.

While other components and systems in an aircraft are indeed responsible for generating electrical power or regulating fuel flow, they do not serve the purpose of initiating engine rotation. Similarly, maintaining hydraulic systems' temperature is unrelated to the function of the starter motor. Understanding the role of the starter motor helps clarify why it is vital for the successful operation of an aircraft's engine during start-up.