What must be done with all equipment at the beginning of every shift?

Testing all equipment at the beginning of every shift is crucial to ensure that everything functions correctly and safely before use. This practice mitigates the risk of equipment failure that could lead to accidents or inefficiencies during operations. By performing tests, operators can identify any issues that might have developed, ensuring that all systems are operational and meet the required safety standards. This routine check is a fundamental component of operational safety and reliability in aviation.

While other options like replacing outdated components, storing equipment properly, and disinfecting might be relevant in certain contexts, they do not specifically address the immediate need to ensure operational readiness. Testing is a proactive measure that directly impacts safety and performance right from the start of a shift.