What occurs if the Pt probe at the engine nose dome opening ices up?

When the Pt probe at the engine nose dome opening develops ice, it can lead to a false reading in the Engine Pressure Ratio (EPR) indication. The Pt probe measures total pressure, and icing can obstruct the probe's ability to measure accurately. As a result, the total pressure reading becomes incorrect, causing the EPR indication to falsely increase.

This is significant in flight operations because an incorrect EPR reading can mislead the flight engineer or pilots about the actual performance of the engine, potentially leading to improper thrust settings or safety concerns. The presence of ice interferes with the pressure measurement, which is fundamental for calculating the engine's thrust output accurately.

In contrast, the other outcomes, such as engine failure to start or fluctuations in thrust settings, may not directly result from ice on the Pt probe. The engine may still start despite the iced probe, and fuel flow would not inherently decrease due to icing on the probe itself.