In the event of a total electrical failure, which element remains unaffected?

In the event of a total electrical failure, the magnetos remain unaffected because they operate independently of the aircraft's electrical system. Magnetos generate their own electrical current to ignite the fuel-air mixture in the engine's cylinders, which is crucial for the engine's operation. This self-contained functionality ensures that even if the electrical system fails, the magnetos can still produce the necessary spark to keep the engine running.

In contrast, the other options rely on the aircraft’s electrical systems. The avionics system requires electrical power to function, meaning it would be inoperative during a total electrical failure. The alternator is an essential component that converts mechanical energy into electrical energy to charge the battery and power electrical systems; thus, it would also be non-functional in this scenario. Lastly, the battery, which stores electrical energy, would not be helpful during a total electrical failure because it could either be depleted or itself be part of the failure. This reinforces the importance of the magnetos in maintaining engine operation, even when all other electrical components fail.