Davis, Edward L.; Grahame, William E.; Loral Instrumentation (International Foundation for Telemetering, 1986-10)
      When flight testing helicopters, it is essential to process and analyze many parameters spontaneously and accurately for instantaneous feedback in order to make spot decisions on the safety and integrity of the aircraft. As various maneuvers stress the airframe or load oscillatory components, the absolute limits as well as interrelated limits including average and cumulative cycle loading must be continuously monitored. This paper presents a complete acquisition and analysis system (LDF/ADS) that contains modularly expandable array processors which provide real time acquisition, processing and analysis of multiple concurrent data streams and parameters. Simple limits checking and engineering units conversions are performed as well as more complex spectrum analyses, correlations and other high level interprocessing interactively with the operator. An example configuration is presented herein which illustrates how the system interacts with the operator during an actual flight test. The processed and derived parameters are discussed and the part they play in decision making is demonstrated. The LDF/ADS system may perform vibration analyses on many structural components during flight. Potential problems may also be isolated and reported during flight. Signatures or frequency domain representations of past problems or failures may be stored in nonvolatile memory and the LDF/ADS system will perform real time convolutions to determine the degrees of correlation of a present problem with all known past problems and reply instantly. This real time fault isolation is an indispensable tool for potential savings in lives and aircraft as well as eliminating unnecessary down time.