As shown in the illustration of a gas turbine fuel oil system, when the engine fuel oil valves are de-energized, the remaining fuel left in the system is recirculated back to which of the following? Illustration GT-0021
• Follow the flow arrows on the lower (B) schematic from the fuel pump outlet, through the fuel control, then see where the flow goes when the shutdown valves and fuel oil valves are closed (de‑energized). • Notice how the pressurizing valve and bypass/relief paths are drawn: excess or blocked fuel is not sent to the nozzles, but instead routed somewhere else. • Think about normal gas turbine design: when fuel to the combustor is shut off, the remaining flow is usually recirculated within the system, not sent all the way back to storage.
• When the fuel oil valves are de‑energized, can fuel still get to the fuel manifold and nozzles, or must it take one of the bypass/relief routes shown? • Look at each labeled component in the answer choices on the diagram: which one clearly has a return line coming from the fuel control/relief devices back toward the low‑pressure side? • If the system constantly circulates fuel during operation, where is the most logical point for unused fuel to return so the pump can pick it up again without sending it back to the tank?.
• Verify which component on the schematic actually has a return line connected to it; ignore any choice that is not shown as a return path. • Confirm that the path you choose stays within the engine fuel system and does not go all the way back to shipboard storage (like a day tank). • Make sure the route you select is associated with the bypass/relief or pressurizing functions, since those control what happens to fuel when the main delivery path is closed.
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