Definition
In sheet metal rivet layout, pitch is the distance between the centers of adjacent rivets in the same row. It is one of the standard spacing dimensions used when laying out a riveted joint, alongside edge distance (distance from the rivet center to the edge of the sheet) and transverse pitch (distance between rows). Rivet pitch is normally expressed in rivet-shank diameters, with a typical minimum of about 3 diameters and a typical maximum of about 10 to 12 diameters, depending on the joint and structural requirements.
Plain English
Pitch is how far apart the rivets are spaced along a single row, measured from the middle of one rivet to the middle of the next.
Context Anchor
Seen in aircraft sheet-metal repair instructions, rivet layout drawings, and maintenance handbook sections that explain how to space rivets correctly.
Derivation
From Middle English picchen, 'to fix or set in place.' The same root gives us 'pitching a tent' — driving stakes at set intervals. In layout work, pitch became the word for the regular spacing between fixed points, which is exactly how it is used for rivets.
Why Pilots Care
Correct rivet pitch is a structural requirement. Rivets spaced too close can weaken the sheet by perforating it like a tear line; spaced too far apart, the joint can buckle or leak between fasteners. A technician laying out a repair must hit the specified pitch for the repair to be airworthy.
Analogy
It is like measuring fence-post spacing from the center of one post to the center of the next, rather than from edge to edge.
Intuition Check
Do not read pitch here as airplane nose attitude, propeller blade angle, or sound. In this maintenance context, pitch means the spacing between rivets.
Example Sentence 1
The repair drawing called for a rivet pitch of four diameters, so with 1/8-inch rivets the centers were spaced 1/2 inch apart.
Example Sentence 2
Check the drawing for the required pitch before drilling the first hole in the repair.