The paper discusses the RAH-66 Comanche airframe building block structural qualification program. The components of the building block program included: material selection and qualification tests (lamina properties); coupon level tests (static and fatigue laminate properties, including open hole and filled hole strength, bearing, and sandwich compression after impact strength), and element, subcomponent, and full-scale tests. Element tests included bolted and bonded joint strength tests, beaded shear panel tests, sandwich shear panel tests, crippling tests and bearing-bypass bolted joint tests. Subcomponent testing included fuselage section crush tests, hydraulic ram testing of fuel tanks, and numerous design specific joint tests. The building block program culminated in the full-scale static test of the airframe structure.
The interaction of the building block program testing with the Comanche detail design is described including specific examples where results from compression after impact, tub crush, and hydraulic ram testing caused changes in the structural configuration of the aircraft. This paper discusses only the Sikorsky Aircraft portion of the RAH-66 building block program. Boeing-Philadelphia also performed a related program to substantiate the design of their portion of the aircraft.