FAA Aviation Mechanic Airframe (AMA)Airframe StructuresEasy
A technician inspecting an older fabric-covered airplane's fuselage finds a framework of welded steel tubing arranged in triangular patterns. The fabric skin covering the framework provides only an aerodynamic shape and streamlining, with no structural load-carrying function. This fuselage structure is best described as which type?
- AMonocoque
- BSandwich
- CSemi-monocoque
- DTruss type
Show answer & explanationAnswer & explanation
Correct answer: D. Truss type
A truss-type fuselage uses a welded tubing framework, typically steel, arranged in triangular patterns to carry all structural loads. The fabric or sheet covering is non-structural and only provides shape.
Why the other options are wrong
- A. Monocoque relies solely on skin, not a tubing framework.
- B. Sandwich structure refers to composite panels with core material, not a tubing frame.
- C. Semi-monocoque relies on stressed skin plus internal stiffeners, not a truss frame.
Truss-Type Fuselage
A fuselage structure built from welded steel tubing arranged in triangular (truss) patterns that carries all structural loads, with the covering providing shape only.
- Triangular tubing arrangement resists loads efficiently
- Common on early and light fabric-covered aircraft
- Covering (fabric/sheet) is non-structural
- Also called a Pratt or Warren truss configuration
Memory trick: Triangles in tubing = truss taking the tension.