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There is a growing need for high voltage direct current (HVDC) power distribution systems in aircraft which provide low-loss distribution with low weight. Challenges associated with HVDC distribution systems include improving reliability and reducing the size and weight of key components such as electric load control units (ELCUs), or remote power controllers (RPCs) for load control and feeder protection, and primary bus switching contactors. The traditional electromechanical current interrupting devices suffer from poor reliability due to arcs generated during repeated closing and opening operations, and are generally slow in isolating a fault with potentially high let-through energy, which directly impacts system safety.

This paper discusses recent improvements made by Honeywell's Condition-Based Maintenance (CBM) Center of Excellence (COE) to Mechanical Health Management (MHM) algorithms. The Honeywell approach fuses Condition Indicators (CIs) from vibration monitoring and oil debris monitoring. This paper focuses on using MHM algorithms for monitoring gas turbine engines. First an overview is given that explains the general MHM approach, and then specific examples of how the algorithms are being refined are presented. One of the improvements discussed involves how to detect a fault earlier in the fault progression, while continuing to avoid false alarms. The second improvement discussed is how to make end of life thresholds more robust: rather than relying solely on the cumulative mass of oil debris, the end of life indication is supplemented with indicators that consider the rate of debris generation.

Modeling and analysis of a reduced order tracking 3-phase Phase-Locked Loop (PLL) based on a combined control principle (error + disturbance) to improve PLL locking performance is presented in this work. The principle is in synthesizing a feedforward control that is added to a Stationary/Floating Frame Transformation PLL or Synchronous (Delta Q) Frame Transformation PLL. The feedforward comprises a frequency-to-voltage converter based on a phase/frequency estimation using an algebraic summation while implementing an inverse feedforward control principle relative to the part of the feedback loop seen after the summing junction. The reduced order tracking PLL is shown to desensitize the system relative to the conventional part PI controller tuning parameters and is operated to lock on either linear or nonlinear load current waveform and for arbitrary frequency/phase profile while maintaining stability by minimizing system dynamics.

Laser Based Powder Bed Fusion, a specific application of additive manufacturing, has shown promise to replace traditionally fabricated components, including castings and wrought products (and multiple-piece assemblies thereof). In this process, powder is applied, layer by layer, to a build plate, and each layer is fused by a laser to the layers below. Depending on the component, it appears that only 3-5% of the powder charged into the powder bed fusion machine is fused. Honeywell’s initial part qualification efforts have prohibited the reuse of powder. Any unfused powder that exits the dispenser (i.e., surrounds the build or is captured in the overflow) is considered used. In order for the process to be broadly applicable in an economical manner, a methodology should be developed to render the balance of the powder (up to 97% of the initial charge weight) as re-usable.

Many avionics and aircraft equipment manufacturers use DO-160 [Ref. 1] Section 22 to test their equipment for indirect effects of lightning without understanding why they are testing to specific values. Many aircraft manufacturers struggle with determining the level of indirect lightning that will be acceptable for their vehicle and what level of requirements they need to pass down to the avionics and aircraft equipment manufacturers. Organizations like SAE and RTCA, Inc. work to collect data on lightning and spend countless hours assimilating the information and developing documents to help engineers use the information. They struggle with knowing what data is pertinent and how it will be received and used by the engineering community.

During participation on EU FP7 HAIC project, Honeywell has developed methodology to detect High Altitude Ice Crystals with the Honeywell IntuVue® RDR-4000 X-band Weather Radar. The algorithm utilizes 3D weather buffer of RDR-4000 weather radar and is based on machine learning. The modified RDR-4000 Weather Radar was successfully flight tested during 2016 HAIC Validation Campaign; the technology was granted Technology Readiness Level 6 by HAIC consortium. After the end of HAIC project, the method was also evaluated with respect to newly set preliminary industry standard performance requirements1. This paper discuses technology design rationale, high level technology architecture, technology performance, and challenges associated with performance evaluation.

The operating environment of aircraft causes accumulation and build-up of contamination on both the narrowest passages of the ECS (Environmental Control System) i.e: the heat exchangers. Accumulated contamination may lead to reduction of performance over time, and in some case to failures causing AOG (Aircraft on Ground), customer dissatisfaction and elevated repair costs. Airframers/airlines eschew fixed maintenance cleaning intervals because of the high cost of removing and cleaning these devices preferring instead to rely on on-condition maintenance. In addition, on-wing cleaning is t impractical because of installation constrains. Hence, it is desirable to have a contamination monitoring that could alert the maintenance crew in advance to prepare and minimize disruption when contamination levels exceed acceptable thresholds. Two methods are proposed to achieve this task, The effectiveness of these methods are demonstrated using analytical and computational tools.

Health Ready Components are essential to unlocking the potential of Integrated Vehicle Health Management (IVHM) as it relates to real-time diagnosis and prognosis in order to achieve lower maintenance costs, greater asset availability, reliability and safety. IVHM results in reduced maintenance costs by providing more accurate fault isolation and repair guidance. IVHM results in greater asset availability, reliability and safety by recommending preventative maintenance and by identifying anomalous behavior indicative of degraded functionality prior to detection of the fault by other detection mechanisms. The cost, complexity and effectiveness of the IVHM system design, deployment and support depend, to a great extent, on the degree to which components and subsystems provide the run-time data needed by IVHM and the design time semantic data to allow IVHM to interpret those messages.

An evaporative heat exchanger system, suitable for rejecting heat in a space environment, has been developed. The system is designed to use water as the evaporant, although other fluids are possible. The major components of the system include an evaporative heat exchanger, water spray nozzles, a back-pressure regulator, a pressurized water supply tank, and appropriate controls. The heat exchanger is a high-performance aircraft-type plate-fin design, with a proprietary hydrophilic coating applied to the evaporant-side flow passages. The hydrophilic coating promotes good contact between the evaporating water and the hot heat transfer surfaces.

An emerging emphasis for the design and development of vehicle condition-based maintenance (CBM) systems amplifies its use for conducting vehicle maintenance based on evidence of need. This paper presents a systems engineering approach to creating an integrated vehicle health management (IVHM) architecture which places emphasis on the system's ultimate use to meet the operational needs of the vehicle and fleet maintainer, to collect data, conduct analysis, and support the decision-making processes for the sustainment and operations of the vehicle and assets being monitored. The demand for a CBM system generally assumes that the asset being monitored is complex or that the operational use of the system demands complexity, timely response or that system failure has catastrophic results. Ground vehicles are such complex systems, which are the emphasis of this paper. Developing the system architecture of such complex systems demands a systematic approach.

This work deals with modeling and analysis of a 3-phase Phase-Locked Loop (PLL) based on an algebraic-summation scheme rather than the Stationary/Floating frame transformation PLL or synchronous (Delta Q) frame transformation PLL, and operated to lock on either linear or nonlinear load current waveform, and in the presence of a loss of phase or unbalanced 3-phase load. The PLL scheme is described and performance results are presented, demonstrating its ability to estimate phase and frequency of the input signal in aerospace applications in which a Unity Vector production and a Frequency-to-Voltage conversion is performed.

This paper focuses on advances in active power converter topologies for power quality solutions for More Electric Aircraft (MEA). Advancements in power electronics encompass many technologies including power semiconductors, microprocessors or digital signal processors (DSPs), and component packaging. Hence, active power electronic solutions are becoming more attractive from the perspective of weight, volume, performance and cost. A particular contribution that leads to these advancements is the feasibility of implementing the robust control topologies using faster processors. In this paper various active topologies are reviewed, but a particular emphasis is given to a novel control topology for an active filtering technique where an overall reduction of current harmonics of an aircraft power distribution system can be achieved at the system level rather than at the Line Replaceable Unit (LRU) level.

Thermal management requirements for aerospace applications continue to grow while weight and volume allotments remain constant or shrink. Compact, high performance and lightweight heat transfer equipment is needed to meet these high heat flux removal requirements. Several innovative heat transfer enhancement techniques are being considered for development of thermal management components that will meet these challenging demands. Honeywell, under an AFRL funded program, is developing two new heat exchanger technologies; microchannel and advanced heat transfer surfaces to improve thermal management systems for a fuel-to-air heat exchanger. Heat transfer systems in military aircraft are increasingly using fuel as a heat sink. Heat transport loops containing several fuel-to-liquid heat exchangers are used to cool electronics, engine oil, hydraulic oil, and elements of the thermal management system.

This paper presents the current state of a three-layer surface icing model for ice crystal icing risk assessment in aircraft engines, being developed jointly by Ansys and Honeywell to account for possible heat transfer from inside an engine into the flow path where ice accretion occurs. The bottom layer of the proposed model represents a thin metal sheet as a substrate surface to conductively transfer heat from an engine-internal reservoir to the ice layer. The middle layer is accretion ice with a porous structure able to hold a certain amount of liquid water. A shallow water film layer on the top receives impinged ice crystals. A mass and energy balance calculation for the film determines ice accretion rate. Water wicking and recovery is introduced to transfer liquid water between film layer and porous ice accretion layer.