In turbine-related high-angle, high-RPM failures, which of the following is listed as a sign?

• A. Disk failure (Correct)
• B. Blade tips curled forward
• C. Shaft sheared
• D. Non-uniform bending

Answer: (A)

When a turbine fails at high angle and high rotational speed, the most telling sign is the disk itself showing failure. The disk is the rotating heart of the turbine, holding the blades and transmitting the loads from the rotor to the blades. At very high RPMs, plus a large blade angle, the stresses on the disk—centrifugal, bending, and shear stresses—increase dramatically. If the disk develops a crack or ruptures, this damage often becomes the dominant, observable sign of the failure mode, because it directly reflects the disk’s inability to carry the imposed loads under those extreme conditions.

Blade-tip damage, like tips curled forward, usually points to blade-level issues such as overheating, impact, or tip loading, not the disk’s integrity. Shaft shearing indicates a break in the rotor shaft, a different failure sequence that isn’t the defining indicator of this specific high-angle, high-RPM failure. Non-uniform bending suggests rotor imbalance or misalignment effects, again not the primary sign of the turbine’s high-angle, high-RPM failure mechanism.