What type of inspection is designed to assess the condition of critical aircraft components?

The selection of a structural inspection as the type of inspection designed to assess the condition of critical aircraft components is well-founded. Structural inspections focus on the integrity of the aircraft's airframe and its components, including wings, fuselage, and tail assembly. These elements are vital for the safety and performance of the aircraft.

During a structural inspection, technicians thoroughly examine for signs of damage, fatigue, or corrosion that could compromise the aircraft's structural integrity. This type of inspection typically involves non-destructive testing methods to ensure that critical components are functioning correctly without causing damage to the structure itself.

In contrast, routine inspections involve general checks and maintenance tasks recommended at regular intervals rather than specific assessments of structural components. Comprehensive inspections may cover a broader spectrum of maintenance but do not specifically target the condition of critical components. Phase inspections are typically part of a program that divides maintenance tasks into phases based on flight hours or cycles, focusing on specific systems rather than exclusively on structural integrity. Thus, the emphasis that structural inspections place on assessing critical aircraft components distinguishes it as the correct answer.