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Digital Systems Technical Analysis.

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Final rept.,

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This study analyzed currently available data specifically related to the reliability of digital avionic systems. It examined the relationships between reliability and airworthiness standards, maintenance programs, integrity, and safety. Reliability data were obtained on both air carrier and general aviation digital systems within the following categories navigation, communications, flight instruments, flight data, and autopilot and flight controls. The analyses focused on identifying the relationships between performance of digital avionics and the following variables of interest failure rate, system category, system design, and system application. The relationships of reliability to existing airworthiness standards, maintenance programs, integrity, and safety are also presented. The data presented indicate that digital systems are capable of performing more reliably than comparable analog systems. The data suggest that a mean time between removal in excess of 2,000 hours is generally achievable through digital design. It is also shown that the number of removals of digital units remains, on the average, twice the number of confirmed failures, as has historically been the case for analog units. During the data collection process, it was found that there are differences in reliability-reporting formats between airlines and between avionics manufacturers. The variations generate some difficulty in developing a composite representation of the reliability of digital avionics. In addition, although the advent of digital technology has enhanced the functional capabilities of avionics, the user community expressed some concern regarding aspects of the implementation, use, and maintenance of digital systems.

Subject Categories:

  • Aircraft
  • Computer Programming and Software
  • Manufacturing and Industrial Engineering and Control of Production Systems

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