Definition
An aircraft fuselage construction method in which the airframe is built from a framework of rigid members — typically steel tubes or wooden beams — joined at the ends to form triangular shapes that carry the structural loads. The outer surface (fabric or thin metal) is non-load-bearing and only provides shape and aerodynamic skin.
Plain English
A skeleton of metal tubes or wooden bars welded or bolted into triangles, with a fabric or light metal cover stretched over it. The triangle frame holds the aircraft together; the cover does not.
Context Anchor
Seen in aircraft construction discussions, especially when describing older, light, or fabric-covered airplanes with tube-and-fabric fuselages.
Derivation
Truss comes from the Old French trousse, meaning 'a bundle' or 'something tied together.' In engineering it came to mean a rigid framework of bars tied together at their ends. The aviation use carries the same idea: a bundle of strong members locked into triangles to share the load.
Why Pilots Care
Understanding truss structures helps pilots recognize the design limitations and inspection points in vintage or light aircraft.
Analogy
Think of a steel-framed bicycle: the welded triangle of tubes does all the carrying, and any paint, decals, or fairings on top are just for looks and airflow.
Intuition Check
Do not think “structure” means only the outside shape or covering of the airplane. Here it means the internal load-carrying frame.
Example Sentence 1
The Piper J-3 Cub uses a welded steel-tube truss structure covered in fabric.
Example Sentence 2
During preflight, the pilot checks for cracks in the truss structure members visible through inspection panels.