In turbine engine investigations, which option indicates a Low RPM - High Angle impact in the compressor?

• A. Blade imprint on case
• B. Non-uniform bending (Correct)
• C. Little case damage
• D. Blades not bent or uneven

Answer: (B)

Non-uniform bending best fits a low RPM, high angle impact in the compressor. When the rotor is turning slowly, blades are more susceptible to deflection, and a foreign object striking at a steep angle loads the blades unevenly. This produces varying bends across different blades rather than a single, uniform deformation. Because most of the energy goes into bending the blades rather than pushing into the case, you often see little case damage. In contrast, a clean case imprint or uniformly bent blades would point to different impact conditions, so the uneven bending pattern specifically points to a low RPM, high-angle impact.