Which option describes the starter operation requirement?

• A. Bleed air from the APU, external ground cart, or the other engine
• B. Electrical power from the airplane battery
• C. Hydraulic power from the aircraft system
• D. Pneumatic air from the cabin

Answer: (A)

Starter operation on most engines uses a pneumatic starter that needs a supply of high‑pressure bleed air to spin the compressor. The option describing bleed air from the APU, an external ground cart, or the other engine identifies the actual source that drives that starter turbine. Electrical power from the aircraft battery doesn’t provide the required high‑pressure air to the pneumatic starter, and hydraulic power or cabin air aren’t used to start the engine. In practice, bleed air can come from the APU when on the ground, from a ground air cart, or via cross‑bleed from another running engine, enabling the starter to turn the engine until ignition starts and the engine takes over.