Scratches or nicks on the straight portion of aluminum alloy tubing may be repaired if they are no deeper than?

• A. 5 percent of the wall thickness
• B. 15 percent of the wall thickness
• C. 10 percent of the wall thickness
• D. 20 percent of the wall thickness

Answer: (C)

Damage assessment for aluminum tubing focuses on how deep a scratch is compared to the wall thickness. For straight sections, shallow nicks can be repaired because they don’t significantly reduce the cross‑section or create a problematic stress concentration. The standard limit is that the scratch depth must be no more than 10 percent of the wall thickness to be repaired. Staying within this limit preserves enough material to maintain strength and fatigue life; once the depth reaches 10 percent or more, replacement is required to avoid compromising structural integrity. The other options don’t fit because they would either be too strict or too lenient compared with the established aircraft maintenance guideline.