FAA Aviation Mechanic Airframe (AMA)Airframe StructuresMedium
A technician is installing 3/32-inch diameter solid rivets in an aluminum skin panel per AC 43.13-1B guidance. What is the minimum edge distance required from the center of the rivet hole to the edge of the sheet?
- A3/16 inch
- B5/16 inch
- C1/8 inch
- D1/4 inch
Show answer & explanationAnswer & explanation
Correct answer: A. 3/16 inch
Standard minimum edge distance for solid rivets is 2 times the rivet shank diameter (2D). For a 3/32-inch (0.09375") rivet, 2 x 0.09375 = 0.1875", which rounds to 3/16 inch. Using an edge distance less than this risks the sheet cracking or the rivet pulling through the edge.
Why the other options are wrong
- B. 5/16 inch is excessive and not derived from the 2D rule.
- C. 1/8 inch is less than 2D and would risk edge cracking.
- D. 1/4 inch exceeds the calculated minimum and is not the standard value used.
Rivet Edge Distance
The minimum distance from the center of a rivet hole to the edge of a sheet, used to prevent the sheet from cracking or the rivet from pulling through under load.
- Standard minimum edge distance = 2 x rivet diameter (2D)
- Flush/countersunk rivets typically require greater edge distance (2.5D)
- Insufficient edge distance is a common cause of rivet repair failure
Memory trick: 'Two Diameters to the Door' — edge distance is always 2x the rivet size.