How should a damaged auxiliary turbine blade be removed when reblading is not feasible?

When dealing with a damaged auxiliary turbine blade where reblading is not feasible, the approach taken must ensure proper balance and operation of the turbine. Removing the damaged blade along with the blade diametrically opposite serves to maintain balance in the rotor assembly. This is crucial because a rotor with an uneven number of blades can become unbalanced due to the loss of one blade, leading to vibrations and potential failure during operation.

Cutting off the damaged blade and its opposite counterpart ensures that the rotor's mass distribution remains symmetric, allowing for smoother operation and reduced risk of further mechanical issues. This method is a common practice in turbine maintenance and reflects an understanding of the importance of rotor dynamics.

The other options would not address the need for balance effectively. Simply replacing the entire rotor may be unnecessary and costly if only a single blade is damaged, while grinding down the damage could potentially weaken the blade structure without resolving the balance issue. Twisting the blade to break it off poses risks of debris or further damage to the turbine assembly. Therefore, removing both the damaged blade and its opposite is the most effective and rational choice.