For diagnosing electrical faults in aircraft systems, which instrument is routinely used?

• A. Multimeter
• B. Oscilloscope
• C. Soldering iron
• D. Thermal camera

Answer: (A)

Diagnosing electrical faults starts with quickly checking basic electrical parameters—voltage, current, resistance, and continuity—to confirm whether a circuit is behaving as it should. The multimeter is the instrument designed for these fundamental checks. It lets you measure DC and AC voltages, test current flow, verify continuity, and check resistance, enabling you to determine if power is present where it should be, if there are opens or shorts, or if a ground path is good. This makes it the go-to tool for routine fault isolation without disassembly, which is why it’s the best choice.

An oscilloscope can be invaluable for analyzing waveforms and transients, but it’s more specialized and requires more setup and interpretation. A soldering iron is for making or repairing joints, not diagnosing faults. A thermal camera can spot hotspots, but it doesn’t provide direct electrical measurements needed for diagnosis.