Minor damage to axial-flow engine compressor blades may be repaired if?

The condition for repairing minor damage to axial-flow engine compressor blades hinges on whether the damage can be removed without exceeding the allowable limits set by the manufacturer. This is critical because every engine component has specific tolerances for wear and deformation, including the compressor blades. When damage is assessed, it must be carefully measured to ensure that removing the damaged material does not compromise the blade's structural integrity or alter its aerodynamic properties beyond what is acceptable.

If the damage is removed while staying within these limits, the blade is still able to perform its required function effectively and safely. This ensures both the reliability of the engine and the safety of the aircraft.

In contrast, surface scratches might not necessarily require repair if they are within limits, and non-visible damage, while theoretically repairable, would not usually be prioritized since it can’t be adequately evaluated. Additionally, just passing a performance test does not address any potential compromises in the structural or aerodynamic integrity of the blade due to the damage. Hence, the key to repairability is ensuring that any removal of material due to damage stays within the manufacturer's specified limits.