FAA Powerplant Written Practice Test

In older reciprocating aircraft inertia starting systems, energy for cranking the engine is stored in the:

1. Battery

2. Flywheel

3. Capacitor

4. Spring mechanism

The correct answer is: Flywheel

In older reciprocating aircraft with inertia starting systems, the energy used for cranking the engine is indeed stored in a flywheel. The flywheel functions by storing kinetic energy when it is spun up by an external power source, such as an electric motor or an engine starter. Once the flywheel is brought up to speed, it can release its stored energy to provide a strong, consistent force to turn the engine's crankshaft, helping to initiate the engine's combustion process. The use of a flywheel in this system takes advantage of rotational inertia, which allows for a steady transfer of energy during the start cycle. This method can prove to be effective in overcoming the static friction of the engine components and getting the engine to the speed required for it to start. In contrast, batteries provide electrical energy, capacitors store electrical charges, and spring mechanisms are typically used in other types of starting systems but do not serve the same function of inertia storage in this context. Thus, the correct identification of the flywheel highlights its role in mechanics and energy transfer specific to inertia starting systems in older reciprocating aircraft.