Validation Technique for on Board Safety Critical Control Law Software for an Aero Engine

Abstract

Testing is an essential part of any aero engine development programme. Combinations of flight and safety critical hardware and software are tested on various platforms before integrating on engine. Extensive tests are carried out to exercise the engine in various modes to ensure reliable performance. One of the vital element of on board safety critical embedded controller software is control algorithms also known as Control Law (CLAW). The Control Laws are coded in C language by the Software House and are extensively tested with the participation of the Independent Verification and Validation (IV & V) group. Various validation techniques are emoloyed before onboard safety critical software flies. A method known as Non- Real Time (NRT) testing is adopted to test the on board safety critical code. In this paper a new approach to conduct NRT testing is addressed. This method helped engine house for formal clearance of onboard safety critical software. The new approach i.e. Gray Box Non-Real Time (NRT) Testing methodology is deployed to cater various tests (normal & Stress) on the Target Control Law (On-board Software). It is a Gray-Box- End to End functionality testing technique without any execution time constraint (Frame by Frame execution) which allows testing of Target Control Law (On-board Software) with static/dynamic inputs, which could cause a system failure and trap the defect.