DATA ACQUISITION SYSTEM FOR AIRCRAFT QUALIFICATION

Abstract

The Boeing Commercial Airplane Company presently uses an Airborne Data Analysis and Monitor System (ADAMS) to support extensive qualification testing on new and modified commercial aircraft. The ADAMS system consists of subsystems controlled by independent processors which preprocess serial PCM data, perform application-specific processing, provide graphic display of data, and manage mass storage resources. Setup and control information is passed between processors using the Ethernet protocol on a fiber optic network. Tagged data is passed between processors using a data bus with networking characteristics. During qualification tests, data are dynamically selected, analyses performed, and results recorded. Decisions to proceed or repeat tests are made in real time on the aircraft. Instrumentation in present aircraft includes up to 3700 sensors, with projections for 5750 sensors in the next generation. Concurrently, data throughput rates are increasing, and data preprocessing requirements are becoming more complex. Fairchild Weston Systems, Inc., under contract to Boeing, has developed an Acquisition Interface Assembly (AIA) which accepts multiple streams of PCM data, controls recording and playback on analog tape, performs high speed data preprocessing, and distributes the data to the other ADAMS subsystems. The AIA processes one to three streams in any of the standard IRIG PCM formats using programmable bit, frame and subframe synchronizers. Data from ARINC buses with embedded measurement labels, bus ID’s, and time tags may also be processed by the AIA. Preprocessing is accomplished by two high-performance Distributed Processing Units (DPU) operating in either pipeline or parallel environments. The DPU’s perform concatenation functions, number system conversions, engineering unit conversions, and data tagging for distribution to the ADAMS system. Time information, from either a time code generator or tape playback, may be merged with data with a 0.1 msec resolution. Control and status functions are coordinated by an embedded processor, and are accessible to other ADAMS processors via both the Ethernet interface and a local operator’s terminal. Because the AIA assembly is used in aircraft, the entire functional capability has been packaged in a 14-inch high, rack-mountable chassis with EMI shielding. The unit has been designed for high temperature, high altitude, vibrating environments. The AIA will be a key element in aircraft qualification testing at Boeing well into the next generation of airframes, and specification, design, development, and implementation of the AIA has been carried out with the significance of that fact in mind.