What does APU stand for in aviation terminology?

• A. Auxiliary Power Unit
• B. Aircraft Power Utility
• C. Air Procedural Unit
• D. Auxiliary Propulsion Unit

Answer: (A)

APU stands for Auxiliary Power Unit. It’s a small turbine installed on many aircraft that provides electrical power and bleed air when the main engines aren’t running or when ground power isn’t available. This lets systems like air conditioning, cabin pressurization, and engine starting operate on the ground or in flight if needed. The other choices don’t fit because they don’t describe the device’s real role or are not standard terms in aviation; the APU is not meant for propulsion, it’s a supplementary power source rather than a propulsion unit.