At what normal interval are main engine turbine bearings measured for wear?

Main engine turbine bearings are typically measured for wear on an annual basis to ensure that they are functioning within the manufacturer's specifications and to prevent any potential failures that could lead to significant operational issues. This interval allows for regular monitoring of the bearings' condition, enabling timely maintenance and replacements as necessary. Conducting these measurements annually provides a good balance between frequency and practicality, ensuring that any wear can be detected and addressed before it leads to more serious complications. Other intervals, such as monthly, quarterly, or every five years, do not align with standard maintenance practices in this context, as they may either be too frequent, leading to unnecessary disruptions, or too infrequent, potentially allowing issues to develop unnoticed.