In propeller engine investigations, which of the following is a sign of a High RPM - High Angle impact in the compressor?

• A. Blade tips curled forward
• B. Disk failure
• C. Shafts and stoppers
• D. Blades severely bent and broken (Correct)

Answer: (D)

A high RPM combined with a high angle of attack in the compressor creates extreme loading on the blades, so the most characteristic damage is blades that are severely bent and broken. The energetic impact and high centrifugal forces under those conditions drive blade fractures and extensive bending, often leaving shattered pieces and mixed debris. Other signs like blade tips curled forward usually point to foreign-object or localized tip damage, disk failures suggest fatigue or overload in the disk itself, and shaft/stoppers issues indicate mechanical misalignment or bearing problems rather than the aerodynamic overloading of the blades. So the severe blade bending and fracture most clearly reflects a high RPM–high angle compressor impact.