What is required for the PTU to continue operating when System B is not functioning?

• A. A hydraulic fluid reserve from System A
• B. Power from the auxiliary power unit
• C. Ground support unit connection
• D. Fluid cooling system

Answer: (A)

The operation of the Power Transfer Unit (PTU) when System B is not functioning relies on a hydraulic fluid reserve from System A. The PTU requires hydraulic fluid to effectively transfer power and maintain operational standards. When System B is down, the PTU utilizes the hydraulic fluid from System A, ensuring that the necessary fluid supply is available to maintain system functionality.

Without this hydraulic fluid reserve, the PTU would not be able to operate effectively, as it depends on the pressurization and flow provided by the fluid. This setup allows the aircraft to maintain its operational capabilities even with one of the hydraulic systems compromised, thereby ensuring safety and functionality during critical operations.

Other options, such as power from the auxiliary power unit or a ground support unit connection, focus on providing electrical power or support resources rather than hydraulic fluid, which is essential for the PTU's operation. Similarly, while a fluid cooling system is important for overall hydraulic operation, it does not directly address the immediate need for hydraulic fluid supply when System B is inoperative.