How are the fabric type and strength requirements determined for fabric-covered aircraft?

• A. The original manufacturer determines the fabric type, and the strength requirements are a function of the never-exceed speed and wing loading
• B. The engineer determines the fabric type, and the strength depends on engine horsepower
• C. The pilot determines the fabric type, and strength is arbitrary
• D. The supplier determines both fabric type and strength

Answer: (D)

Fabric type and strength are dictated by the aircraft’s design data and the loads the structure must carry, not by who happens to pick the material. The original manufacturer specifies which fabric type and what strength are approved for the airframe, based on the expected flight loads—the stresses the skin must endure and how those stresses relate to factors like wing loading and the maximum allowable airspeed. The fabric is chosen to meet those design requirements, and the supplier provides fabric that conforms to that approved spec. Engine horsepower doesn’t determine fabric strength, the pilot doesn’t set the material, and the supplier doesn’t decide the required strength—the design data does.