What critical safety measure must be taken before inspecting a turbine engine?

Before inspecting a turbine engine, it is crucial to ensure that the engine is shut down and grounded. This safety measure is vital because turbine engines can contain residual energy even after shutdown, which could lead to unintended movement of components or the release of high-energy materials. Grounding the engine ensures that there is no chance of electrical hazards, such as accidental startup or static discharge, which could pose serious safety risks to the person performing the inspection.

Moreover, a powered-on engine can result in severe injuries, as turbine engines have moving parts that can cause harm if they are not properly de-energized. Inspecting a turbine engine without these safety precautions not only endangers the mechanic or inspector but also compromises the overall safety of the aircraft operation. Grounding ensures that all systems are safe to approach and inspect, aligning with industry safety standards and practices.

Other considerations, such as checking fuel and oil levels, do play a role in maintenance and operational readiness but are not as critical as ensuring the engine is powered down and properly grounded before performing an inspection.