Aircraft riveting review

When laying out your rivet pattern, you must first calculate and mark out the edge distance of the first rows of rivets in relation to the edge of the repair. This distance should not be less than two and not more than four-rivet shank diameters away from the edge.

Rivet Pitch should next be calculated and laid out. What this means is that rivets cannot be placed closer than three rivet shank diameters and no more than ten rivet shank diameters (normally) away from each other. Diagonal rivet pitch is usually maintained at 75 percent of the pitch of the rivet rows, however, the minimum diagonal rivet pitch allowable is two and a half rivet shank diameters.

When the rivet pattern is non standard on the aircraft itself and there is no real guidance provided in the structural repair manual for the aircraft that you are working on, you should try and duplicate the pattern that was in place before the damage occurred, but you must lay out the repair in accordance with data that is acceptable and approved by the FAA Administrator, i.e. AC43.13. 1A/2A (recently updated to AC43.13b) and or a repair issued by a Designated Engineering Representative (DER) certified under FAA Form 8110-3. Once the layout for the repair has been completed, you are now ready to select the correct size drills for the rivets that you are to use. To make a clean hole that is free from burrs and is the correct size and shape, it is customary to first drill the hole undersize with a pilot drill and then either drill to the correct size of the rivet shank diameter being used, or use a reamer to achieve the correct hole size, or in the case of a highly stressed component, use a hydraulic powered mandrel to upsize to the correct diameter and to stress relive the hole.

Always use a center punch to mark the position of the required rivet holes. This will ensure that you do not wander and dance across the metal surface, causing damage to the corrosion resistance coating of the metal and creating stress risers in the surface that may turn into cracks later.

Once drilled, return with a drill that has a much larger diameter than what you have just drilled and slowly and lightly rotate this drill in your fingers over the mouth of the hole to remove any burrs that may be present. Be careful not to remove any of the base metal during this operation.