Aircraft system voltages can be either DC (14 or 28 VDC) or AC (115 or 200 VAC).

• A. True
• B. False
• C. Not a standard
• D. Sometimes both

Answer: (A)

Power in aircraft is provided by two distinct electrical systems: DC and AC. The DC system is used to run most onboard equipment and is commonly around 28 VDC, though 14 VDC appears in some smaller or older installations. The AC system handles different loads and is typically 115 VAC, often at 400 Hz, with some designs using 200 VAC in a three-phase setup. Since many aircraft have both DC and AC networks, the voltages used can be either DC (14 or 28 VDC) or AC (115 or 200 VAC) depending on the specific aircraft and subsystem. Matching the equipment to its designated voltage type is essential for proper operation.