What does a black "smoky" residue from rivets on an aircraft indicate?

The presence of a black "smoky" residue from rivets on an aircraft is an indication of fretting corrosion. This type of corrosion happens when there are minute, repetitive movements between the rivet and the material it is fastened to, which can occur due to vibration or other stresses. The oxidative reactions involved in fretting lead to the formation of wear debris and corrosion products, which often present as a dark, smoky residue. This residue can compromise the integrity of the structural joint, emphasizing the need for thorough inspections and potential remediation to maintain aviation safety.

Understanding this phenomenon is crucial in the field of aircraft maintenance and inspection because it highlights the importance of monitoring areas where rivets are used, especially in high-vibration environments. Fretting corrosion, if left unchecked, can lead to further structural failures, making it essential to recognize and address it promptly.