Where does bleed air for the T-6A systems come from?

The bleed air for the T-6A systems is sourced from the left and right engine compressor P3 ports. This high-pressure air is utilized for various functions, such as starting the engine, providing pressurized air for aircraft systems, and pressurizing environmental controls.

The P3 ports are strategically positioned to tap into the engine's compressor stage, where the air is compressed and heated, making it suitable for these applications. By using air directly from the engines, the systems can maintain efficiency and ensure reliable performance during different phases of flight.

The other options do not provide bleed air suitable for the aircraft's operational needs. Fuel tanks do not generate any pressurized air, and the main hydraulic reservoir is primarily responsible for hydraulic fluid storage, not air. Environmental control units manage the aircraft's climate and comfort but rely on the bleed air from the engines for their operation, rather than serving as a source themselves.