FAA Powerplant Written Practice Test

Why is it improper to attempt to straighten a bent crankshaft?

1. It can lead to balance issues

2. It will damage the hardened surfaces

3. It may require special tools

4. It will increase wear on bearings

The correct answer is: It will damage the hardened surfaces

Attempting to straighten a bent crankshaft is improper primarily because it can damage the hardened surfaces of the crankshaft. Crankshafts undergo a heat treatment process that hardens them, allowing them to withstand significant stress and maintain structural integrity during operation. When excessive force is applied in an attempt to bend the shaft back into shape, it can cause microfractures or a reduction in hardness in those critical surfaces. This damage can lead to premature failure of the crankshaft, as well as adversely affect the engine's performance and longevity. Other factors such as balance issues, the need for special tools, or increased wear on bearings can be consequences of an improperly aligned crankshaft, but the immediate concern with bending it back is the potential damage to its hardened surfaces. Once those surfaces are compromised, it significantly affects the crankshaft's ability to function effectively within the engine.