What is one common tool used by CDIs during inspections?

A checklist based on applicable technical data is a fundamental tool for Collateral Duty Inspectors (CDIs) during inspections. This tool serves several purposes that enhance the accuracy and consistency of inspections. First, it allows CDIs to systematically verify that all required criteria and standards outlined in technical data are met. This is crucial in ensuring compliance with safety regulations, maintenance standards, and operational requirements.

Using a checklist not only helps in identifying any discrepancies or issues that need to be addressed but also maintains a record of what has been inspected. This documentation is vital for accountability and traceability, should any questions arise regarding the inspection process. It's an essential means of ensuring thoroughness and mitigating the risk of overlooking critical steps in the inspection process.

In contrast, the other choices, while useful in specific contexts, do not serve the same foundational role that a checklist does within the CDI inspection framework. A microphone is not relevant to inspection activities, a personal inspection log may be helpful for individual record-keeping but lacks the structured guidance that a checklist provides, and a digital camera can assist in documenting findings but does not ensure that all inspection criteria are systematically addressed.