Is it considered normal for a turbine blade to be loose at any point during operation?

The idea that a turbine blade may be loose during operation is considered normal because of the need for thermal expansion. As the turbine operates, it experiences significant temperature changes, leading to thermal expansion of the materials. This expansion facilitates movement and can result in slight looseness at certain points.

Some turbine designs incorporate features that allow for this thermal expansion, ensuring that the blade will not bind and will function effectively under varying temperature conditions. If the blade were overly rigid, it would risk structural failure due to thermal stresses. Therefore, a controlled amount of movement is necessary to accommodate these changes without compromising the turbine's integrity.

Other options suggest complete rigidity or condition-based looseness that isn't supported by standard turbine operation practices. Understanding the operational characteristics in relation to thermal dynamics is key to grasping why some looseness could be acceptable during certain operational phases.