Final answer:
The APU, or Auxiliary Power Unit, on aircraft obtains its fuel from the main fuel tanks that also supply the engines. This is critical for both operational efficiency and national security, as highlighted by concerns over diminishing petroleum supply.
Step-by-step explanation:
The Auxiliary Power Unit (APU) is an important component on aircraft, providing power for various systems when the main engines are not running. The APU gets its fuel supply from the aircraft's main fuel tanks. This is the same source that supplies fuel to the engines. Use of the APU is particularly crucial during times when the aircraft is on the ground, and its engines are not operational, or when additional power is required in flight.
Considering the strategic implications, as highlighted by visits from U.S. military strategists worried about diminishing petroleum supply, the reliance on fuel for APUs is significant. It underscores the importance of a steady and secure energy source not just for operational efficiency but also for national security, especially at remote outposts like those on the Aleutian Islands in Alaska.