FAA Powerplant Written Practice Test

When inspecting an axial flow compressor blade, which section offers the greatest tolerance for damage repair?

1. Inboard section, leading edge

2. Mid-span section

3. Outboard section, leading edge

4. Root section

The correct answer is: Outboard section, leading edge

The outboard section, particularly the leading edge of an axial flow compressor blade, tends to offer the greatest tolerance for damage repair. This is because the aerodynamic loading and the flow dynamics are less pronounced at the outboard regions compared to the root section where blades experience significant stress and fatigue due to their proximity to the engine casing. Repairs in the outboard section can often be made without severely compromising the structural integrity and efficiency of the blade. Moreover, the leading edge of the outboard section might be designed with materials or coatings that can survive minor damage or erosion, thus allowing for successful re-contouring or repair. In contrast, the inboard section and root section experience more intense airflow and mechanical stresses, making repairs in these regions more critical and restrictive. The mid-span section also carries risks related to aerodynamic performance, and while it may tolerate some damage, it does not typically match the repair capabilities found in the outboard leading edge.