ABSTRACT
This chapter defines four scenarios for Previously Developed Hardware (PDH). They are: modifications to previously developed hardware, change of aircraft installation, change of application or design environment, and upgrading a design baseline. It addresses different aspects of PDH that may be applied alone, it is more common for more than one of them to apply to any given use of PDH. The majority of airborne electronic hardware is composed of commercial off-the-shelf parts ranging from the simplest passive components to the most complex integrated circuits. However, DO-254 also states that the basis for using COTS components is the use of an electronic component management plan (ECMP) in conjunction with the design process. Qualifying a design tool requires that the confidence in the tool be commensurate with the design assurance level of the hardware it is producing. The advantage of qualifying a tool is that the tool output can be trusted and is thus exempt from further scrutiny.
