What type of verification involves an inspection without the aid of diagnostic equipment?

The correct choice is visual process verification, as this type involves an inspection relying on the observer's eyesight to assess the condition or integrity of an object or system. It is a fundamental form of verification that allows maintainers to detect visible signs of wear, damage, or improper installation without needing specialized diagnostic tools or equipment.

Visual process verification is commonly used in various maintenance and aircraft inspections, where the primary goal is to confirm that everything appears as it should be based upon visual assessment. This practical approach is essential in aeronautics for ensuring safety and compliance with maintenance standards before proceeding with further diagnostic processes or repairs.

In contrast, mechanical verification involves checking the physical aspects or functioning of components using specific tools or gauges, aerodynamic verification focuses on assessing the performance of components based on airflow characteristics, and digital verification typically includes the use of technology and diagnostic systems to evaluate conditions. These methods rely on equipment and instrumentation, which distinguishes them from the straightforward visual techniques used in visual process verification.