Which environmental component does not require the use of engine bleed air?

The environmental component that does not require the use of engine bleed air is air conditioning. In the T-6B, the air conditioning system can operate independently of engine bleed air by utilizing other methods of cooling, such as through the use of refrigerants in the air conditioning cycle.

The other components, such as canopy defogging, cockpit heating, and cockpit pressurization, rely on engine bleed air. Bleed air is drawn from the engine to provide the necessary heat and airflow for defogging and heating operations, as well as to maintain appropriate pressurization levels in the cockpit. Thus, air conditioning stands out as the process that does not depend on this source, instead utilizing mechanical means to maintain a comfortable environment for the crew.