How is the pressure seal inflated in the T-6B?

The correct method of inflating the pressure seal in the T-6B is by using engine bleed air tapped off the left P3 port. This system is designed to maintain the integrity of the aircraft's cabin pressure and assist in various functions, including environmental controls.

The use of bleed air from the left P3 port is established in the aircraft's design for efficiency and safety, ensuring that the pressure seal functions effectively during different phases of flight. Using engine bleed air is common in aircraft systems as it harnesses the existing engine output to provide necessary pressures without requiring additional systems or components.

Additionally, the other options involve sources of pressure that are either not utilized or are unsuitable for this specific function. Hydraulics, for example, serve different purposes within an aircraft, primarily for actuation rather than for inflation of seals. Using bleed air from the right P3 port or ground services could either be inefficient or not in line with standard operating procedures for the T-6B, as the left P3 port is designated for this essential function.