FAA Powerplant Written Practice Test

What is a result of "flash-over" in a distributor?

1. Overheating of the ignition coil

2. Conductive carbon trail

3. Failure to start the engine

4. Increased engine noise

The correct answer is: Conductive carbon trail

The phenomenon of "flash-over" in a distributor occurs when a high-voltage spark jumps from one terminal to another, rather than traveling along the intended path to the spark plug. This results in the formation of a conductive carbon trail, which is a pathway created by the electrical discharge that can form within the distributor cap or on the ignition wires. Over time, this carbon buildup can lead to further electrical problems, as the engine may struggle to operate correctly. While it’s important to note that flash-over can negatively impact engine performance, leading to issues such as difficulty starting or increased noise, the most direct consequence of flash-over itself is the creation of this conductive carbon trail. This trail provides a path for electrical currents that can bypass the normal igniting sequences, potentially complicating operation and maintenance further down the line. It's crucial to address the underlying causes—like moisture damage or wear in the ignition system—to prevent flash-over and its cascading effects.