A blocked EPR outlet probe during climb causes the engine to behave as if what?

• A. Over-read causing underspeed
• B. Under-read causing an overspeed
• C. No change
• D. Readouts oscillate

Answer: (B)

A blocked EPR outlet probe causes the indicated EPR to appear lower than the actual value. The engine’s thrust-control system uses that reading to set fuel flow and thrust. If the signal looks too low, it commands more thrust to achieve the target EPR, which can drive the engine toward a higher speed than intended—an overspeed. In climb, this mismatch between the true thrust and the sensed low EPR leads the engine to behave as if the EPR is under-read, pushing toward an overspeed. The situation wouldn’t be a nonchange or cause oscillating readouts; it’s a sensor fault that makes the system think more thrust is needed, risking overspeed.