FAA Powerplant Written Practice Test

What is the purpose of shielding on spark plug and ignition wires?

1. To enhance energy transfer

2. To reduce power loss

3. To prevent interference with radio reception

4. To improve durability of wires

The correct answer is: To prevent interference with radio reception

The purpose of shielding on spark plug and ignition wires primarily revolves around preventing electromagnetic interference (EMI) that can affect other electronic systems, particularly radio reception. Ignition systems generate high-voltage pulses, which can emit electromagnetic emissions. If these emissions are not managed, they can lead to noise in communication systems, resulting in poor radio reception and other electronic malfunctions. Shielding serves as a barrier that contains these emissions, ensuring that the signals are contained within the wires and do not interfere with sensitive equipment. This is vital in aviation, where clear communication is critical for safety and operation. Proper shielding thus ensures that ignition system operation does not compromise essential avionics functionality. This aspect makes shielding particularly important in maintaining the integrity and performance of both the ignition system and any electronic systems in proximity.