FAA Aviation Mechanic Airframe (AMA)Airframe InspectionHard
During a visual inspection of a riveted aluminum lap joint, a technician observes a dark, sooty stain radiating from around several rivet heads. What does this condition most likely indicate?
- ARelative movement between the rivet and the skin, known as a 'smoking rivet,' indicating a working or fatigued joint
- BExcess sealant applied during original assembly
- CSurface oxidation unrelated to structural condition
- DNormal residue from the original manufacturing process
Show answer & explanationAnswer & explanation
Correct answer: A. Relative movement between the rivet and the skin, known as a 'smoking rivet,' indicating a working or fatigued joint
'Smoking rivets' describes dark residue around a rivet caused by fretting movement between the rivet and skin, which forces out fine aluminum oxide powder from the joint. This is a visual indicator of a working (fatigued or loose) rivet joint that requires further investigation, such as NDT or replacement.
Why the other options are wrong
- B. Excess sealant would not typically produce the characteristic sooty smoking pattern.
- C. Simple oxidation does not create the radiating dark staining pattern associated with rivet movement.
- D. Manufacturing residue would not appear as fresh dark staining radiating outward from rivets during in-service inspection.
Smoking Rivets
A visual indication of dark staining around a rivet caused by relative movement (fretting) between the rivet and surrounding skin, signaling a fatigued or loose joint.
- Caused by fretting motion producing aluminum oxide dust
- Common on riveted lap joints under cyclic loading
- Warrants further inspection (NDT) or rivet replacement
Memory trick: 'Smoking rivet' = the joint is literally crying out that it's loose