Define a short to ground with a practical avionics example.

Define a short to ground with a practical avionics example.

• A. A conductor breaks the connection.
• B. A conductor touches the positive supply.
• C. A conductor becomes in contact with the airframe, creating a low-resistance path to ground.
• D. A conductor loops back to itself.

Answer: (C)

The main idea is a fault path to ground that creates a high fault current because the conductor finds a low-resistance return through the airframe, which is the aircraft’s ground reference. In avionics, the metal airframe is tied to the electrical system’s ground, so when a conductor unintentionally contacts the airframe, current can flow directly from the power source to ground through that metal path. A practical example is a 28 V DC power lead feeding a cockpit radio whose insulation wears through and allows the positive supply to touch the aluminum airframe. The result is a strong fault current that will trip a circuit breaker or blow a fuse, and can cause overheating or damage if protection isn’t fast enough. This is distinct from an open circuit (the conductor simply breaks, no current), a loop back to itself (no ground path), or a conductor touching the positive supply without a ground path driving current back—none of those create the same low-resistance path to ground.

The main idea is a fault path to ground that creates a high fault current because the conductor finds a low-resistance return through the airframe, which is the aircraft’s ground reference. In avionics, the metal airframe is tied to the electrical system’s ground, so when a conductor unintentionally contacts the airframe, current can flow directly from the power source to ground through that metal path. A practical example is a 28 V DC power lead feeding a cockpit radio whose insulation wears through and allows the positive supply to touch the aluminum airframe. The result is a strong fault current that will trip a circuit breaker or blow a fuse, and can cause overheating or damage if protection isn’t fast enough. This is distinct from an open circuit (the conductor simply breaks, no current), a loop back to itself (no ground path), or a conductor touching the positive supply without a ground path driving current back—none of those create the same low-resistance path to ground.