What is an all-weather spark plug?

What is an all-weather spark plug?

• A. A shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a watertight seal.
• B. An ordinary spark plug with extra weatherproof coating.
• C. A spark plug that runs cooler.
• D. A plug designed for turbocharged engines.

Answer: (A)

An all-weather spark plug is built to keep moisture from entering the connection between the spark plug and its ignition lead. The feature described—shielding with a recess that allows a resilient grommet on the ignition lead to form a watertight seal—creates a moisture barrier at the interface. This prevents rain, spray, or wet conditions from getting into the plug, reducing misfires and corrosion in adverse weather, which is especially important in aviation. The other ideas don’t address that waterproof interface. Merely coating the plug won’t guarantee a watertight seal. Running cooler relates to heat range, not weather sealing. Designing for turbocharged engines is about boosted air intake, not weather resistance at the plug connection.

An all-weather spark plug is built to keep moisture from entering the connection between the spark plug and its ignition lead. The feature described—shielding with a recess that allows a resilient grommet on the ignition lead to form a watertight seal—creates a moisture barrier at the interface. This prevents rain, spray, or wet conditions from getting into the plug, reducing misfires and corrosion in adverse weather, which is especially important in aviation.

The other ideas don’t address that waterproof interface. Merely coating the plug won’t guarantee a watertight seal. Running cooler relates to heat range, not weather sealing. Designing for turbocharged engines is about boosted air intake, not weather resistance at the plug connection.