1 Analysis of Key Characteristic Methods and Enablers Used in Variation Risk Management

A hierarchical tree structure is commonly used to describe the Key Characteristics of a product. This tree structure, referred to as a KC flowdown, links customer requirements of the product to its component features. KC flowdowns allow for a decomposition of the product into essential features and processes – enabling traceability of cause and effect. An example of a simple representation of a KC flowdown for aerodynamics and contour characteristics for an aircraft wing assembly is given in Figure 1.1 [Lee & Thornton, 1996]. System level KCs are identified at the highest level of the flowdown and are product requirements that are necessary to meet the organization’s customer requirements. For example, a high-level requirement (Class A Requirement 1, A
Specification, or Type 1 Requirement) from a defense contract can be flowed down to an aerodynamics system-level KC for the product. System-level KCs are requirements for the product which must be maintained to meet performance requirements and customer satisfaction.