FAA Aviation Mechanic Airframe (AMA)Airframe StructuresMedium
A technician is laying out a single row of rivets using 1/8-inch (0.125 in) diameter rivets for a skin splice repair. Using the general rule of a minimum pitch of 6 times the rivet diameter, what is the minimum acceptable spacing between rivet centers?
- A0.375 inch
- B1.00 inch
- C0.50 inch
- D0.75 inch
Show answer & explanationAnswer & explanation
Correct answer: D. 0.75 inch
Minimum rivet pitch = 6 × diameter = 6 × 0.125 in = 0.75 inch. Spacing rivets closer than this minimum can weaken the sheet between rivets and reduce joint strength.
Why the other options are wrong
- A. This is too close (about 3D), risking sheet tear-out between rivets.
- B. This is 8D, an acceptable maximum, not the minimum spacing.
- C. This equals 4D, still under the accepted 6D minimum guideline.
Rivet Pitch (Spacing)
The center-to-center distance between rivets in the same row, generally specified as 6 to 8 times the rivet diameter for standard sheet metal repairs.
- Minimum pitch: approximately 6D to avoid sheet weakening.
- Typical maximum pitch: approximately 8D to maintain load transfer.
- Pitch works alongside edge distance and row spacing in repair layout.
Memory trick: '6 to 8 times D' — six to eight rivet diameters apart, like fence posts spaced evenly