Inspection of Riveted Joints

Riveted joints must be inspected at all stages of production and operation. This means that the manufacturing stages must be thoroughly inspected to ensure that the finished work meets the required specifications.

Whilst in service, rivets must be inspected regularly, to check for a number of faults that might have occurred, such as corrosion, fretting and fatigue.

After the rivets have been closed, they should be inspected to ensure that they are tight and fully formed. Rivet heads must not be deformed or cracked and the surrounding area must be free from distortion and undamaged by riveting tools.

All aircraft maintenance manuals contain diagrams of formed rivets and their possible faults (refer to figure below). These diagrams show what is acceptable and what is not.

FIGURE

Whilst rivets that are clearly not satisfactory must be changed, care must be taken when considering replacing those only slightly below standard. It is possible that more harm could be done replacing them, than leaving them in place.

If there are any signs of damage to the airframe structure, then a thorough inspection of the whole area must be made. Hidden damage may extend beyond the area of visible deformation, so that any riveted joint that shows an indication of damage should be inspected well beyond the last deformed rivet.

Inspection of a rivet head for stretch can be achieved by sliding a feeler gauge under the head or tail. A staining colour of black or grey around a rivet head is an indication that it has stretched. If any doubt exists, it may be necessary to drill out the rivet and examine the hole for indications of elongation or tearing. Any stretching will become apparent when the rivets are removed, as the skin will move position.

Once the material has settled it may be necessary for the holes to be drilled out oversize, providing this is in accord with the repair publications.