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The Cloud Detectability Conundrum

Collins Aerospace-Darren Glenn Jackson
Published 2019-06-10 by SAE International in United States
Since the beginning of aviation, aircraft designers, researchers, and pilots have monitored the skies looking for clouds to determine when and where to fly as well as when to deice aircraft surfaces. Seeing a cloud has generally consisted of looking for a white / grey puffy orb floating in the sky, indicating the presence of moisture. A simple monitoring of a temperature gauge or dew point sensor was used to help determine if precipitation was likely or accumulation of ice / snow on the airframe could occur.Various instruments have been introduced over the years to identify the presence of clouds and characterize them for the purposes of air traffic control weather awareness, icing flight test measurements, and production aircraft ice detection. These instruments have included oil slides, illuminated rods, vibrating probes, hot wires, LIDAR, RADAR, and several other measurement techniques. Each technology has its own strength and weakness including the particle size range and water content that can be measured and its ability (or lack thereof) to discriminate different types of icing conditions.The FAA release…
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SLD and Ice Crystal Discrimination with the Optical Ice Detector

Collins Aerospace-Kaare J. Anderson, Mark D. Ray
Published 2019-06-10 by SAE International in United States
In response to new safety regulations regarding aircraft icing, Collins Aerospace has developed and tested an Optical Ice Detector (OID) capable of discriminating among icing conditions appropriate to Appendix C and Appendix O of 14 CFR Part 25 and Appendix D of Part 33. The OID is a short-range, polarimetric lidar that samples the airstream up to ten meters beyond the skin of the aircraft. The intensity and extinction of the backscatter light correlate with bulk properties of the cloud, such as water content and phase. Backscatter scintillation (combined with the outside air temperature from another probe) signals the presence of supercooled large droplets (SLD) within the cloud-a capability incorporated into the OID to meet the requirements of Appendix O.Recent laboratory and flight tests of the Optical Ice Detector have confirmed the efficacy of the OID to discriminate among the various icing conditions. Drizzle-sized droplets, mixed with a small droplet cloud in the Collins Cloud Chamber, appear as scintillations in the lidar signal when it is processed pulse-by-pulse. Averaging the signal over multiple pulses, causes…
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Effect of Icing Environment and Humidity on Reference Air Data Parameters in an Icing Tunnel

Collins Aerospace-Mac Whalen, Brian Matheis
Published 2019-06-10 by SAE International in United States
Wind tunnel facilities typically rely upon reference instrumentation combined with isentropic flow relationships to define the fluid properties in the test section. For the particular case of icing wind tunnels, the icing environment can affect the airflow such that the definition of test section parameters via isentropic relationships is not strictly correct. These influences are of particular importance for testing air data probes because the nature of the test is to evaluate the performance of a sensor directly measuring the parameters being affected. Momentum, heat, and mass transfer from the water phase to the air phase can result in total temperature and total pressure measurements in the test section that differ from those measured at an upstream station, where reference measurements are typically taken. This effect was first observed by Luers & Fiscus [1] in the context of wind tunnel tests for heavy rain conditions.
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Four Years of Testing to AS5562

Collins Aerospace-Brian D. Matheis, Mac Whalen
National Research Council Canada-Catherine Clark
Published 2019-06-10 by SAE International in United States
With the publication of SAE AS5562 in 2015, icing wind tunnel test facilities have upgraded their operating environments and instrumentation to meet the client demand to test to this new standard. Nearing four years of testing and development to this standard, numerous questions and challenges have arisen that industry has addressed on an individual basis but not in a common format for all. This paper addresses some of the known challenges in an effort to apply AS5562 consistently across industry and provide clarity to all users.
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Experiences of Civil Certification of Multi-Core Processing Systems in Commercial and Military Avionics, Integration Activities, and Analysis

SAE International Journal of Advances and Current Practices in Mobility

Collins Aerospace-Harold Glenn Tiedeman
Wind River UK Ltd.-Paul Parkinson
  • Journal Article
  • 2019-01-1382
Published 2019-03-19 by SAE International in United States
Avionics systems are currently undergoing a transition from single core processor architectures to multi-core processor architectures. This transition enables significant advantages in reduction in size, weight, power (SWaP) and cost. However, avionics hardware and software certification policies and guidance are evolving as research and experience is gained with multi-core processor architectures. The unique challenges of using multi-core processors in certified avionics will be discussed. The requirements for a virtualization platform supporting multiple real-time operating system (RTOS) partitions on a multi-core processor used in safety-critical avionics systems are defined, including the ability to support multiple design assurance levels (DAL) on multiple cores, fault isolation and containment, static configuration as per ARINC 653, role-based development as per DO-297, and robust partitioning to reduce cost of incremental certification. The paper will present a collaborative approach undertaken by a leading avionics system supplier and a leading safety-critical commercial-off-the-shelf (COTS) RTOS supplier in the development of a multi-core real-time system with DO-178C DAL A software and DO-254 DAL A hardware safety certification on an FAA Program of Record (PoR). The…
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