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Performance of Avionics systems is dictated by the timely availability and usage of critical health parameters. Various sensors are extensively used to acquire and communicate the desired parameters. In today's scenario, sensors are hardwired. The number of sensors is growing due to automation which increases the accuracy of intended Aircraft functions. Sensors are distributed all over the Aircraft and they are connected through wired network for signal processing and communication. LRUs (Line Replaceable Unit) which are integrating various sensors also use a wired approach for communication. The use of a wired network approach poses challenges in terms of cable routing, stray capacitances, noise, mechanical structure and added weight to the structure. The weight of cables contributes significantly to the overall weight of the aircraft. As the weight of Aircraft increases, the required fuel quantity also increases. The Key driver for Airline operational cost is fuel.

The Environmental Control System (ECS) of an aircraft provides thermal and pressure control of the engine bleed air for comfort of the crew members and passengers onboard. For safe and reliable operation of the ECS under complex operating environments, it is critical to detect and diagnose performance degradations in the system during early phases of fault evolution. One of the critical components of the ECS is the heat exchanger, which ensures proper cooling of the engine bleed air. This paper presents a wavelet-based fouling diagnosis approach for the heat exchanger.

Cavitation erosion in aircraft engine and control systems is a major concern in hydrodynamic power units. In developing turbulent flow of low pressure and high velocities, a certain amount of cavitation erosion is not unusual. Cavitation can occur with the presence of fuel vapor or air bubbles dissolved in the fuel tank that are transported through the system. Cavitation erosion is caused by collapse of the bubble, which occurs violently and creates a pressure shock wave of fluid. Striking a solid surface, the shock wave can cause progressive damage if it persists. A kinetic cavitation power rate is developed to make a meaningful estimation of the cavitation erosion rate theoretically, which then can be validated with laboratory experiments. Theoretically, we manipulate parameters such as bubble size, collapse pressure, and energy for a given fuel system design, finding variation within each component of the system.

Most of the real world problems pose practical challenges for making decisions primarily due to availability of limited data. Quantification of risk and assessment of structural reliability becomes difficult in such scenarios. Techniques for performing safety analysis for such problems are discussed in this paper. While complete characterization of a system behavior may be difficult with limited data of its response, statistical models based on extreme value theory provide the basis for making decisions with reasonable confidence. The same may not be true, however, for such structures early in their design cycle due to limited experience of their performance. In such cases response surface methodology can be very useful in determination of risk and suitably making modifications to the design to improve the reliability of the component or system. Applications of these methods for some real world scenarios are demonstrated.

This paper addresses the issues of Fault Detection and Isolation (FDI) in complex networked systems such as the Environmental Control System (ECS) of an aircraft. The ECS controls and supplies pressurized air to the aircraft and consists of multiple subsystems that in turn consist of interconnected components, heterogeneous sensing devices, and feedback controllers. These complex interconnections and feedback control loops make fault detection and isolation a very challenging task in the ECS. For example, a faulty component yields off-nominal outputs which are inputs to the other coupled components. This coupling leads to off-nominal outputs from otherwise healthy components, thus causing unwanted false-alarms. Secondly, due to off-nominal inputs, the healthy components are driven beyond their normal operating conditions, leading to cascading failures.

Aircraft icing has been a focus of the aviation industry for many years. While regulations existed for the certification of aircraft and engine ice protection systems (IPS), no FAA or EASA regulations pertaining to certification of ice detection systems existed for much of this time. Interim policy on ice detection systems has been issued through the form of AC 20-73A as well as FAA Issue Papers and EASA Certification Review Items to deal mainly with Primary Ice Detection Systems. A few years ago, the FAA released an update to 14 CFR 25.1419 through Amendment 25-129 which provided the framework for the usage of ice detection systems on aircraft. As a result of the ATR-72 crash in Roselawn, Indiana due to Supercooled Large Droplets (SLD) along with the Air France Flight 447 accident and numerous engine flame-outs due to ice crystals, both the FAA and EASA have developed new regulations to address these concerns.

Turbulence is by far the number one concern of anxious passengers and a cause for airline injuries. Apart from causing discomfort to passengers, it also results in unplanned downtime of aircrafts. Currently the Air Traffic Control (ATC) and the meteorological weather charts aid the pilot in devising flight paths that avoid turbulent regions. Even with such tailored flight paths, pilots report constant encounters with turbulence. The probability of turbulence avoidance can be increased by the use of predictive models on historical and transactional data. This paper proposes the use of predictive analytics on meteorological data over the geographical area where the aircraft is intended to fly. The weather predictions are then relayed to the cloud server which can be accessed by the aircraft planned to fly in the same region. Predictive algorithms that use Time series forecasting models are discussed and their comparative performance is documented.

In the last two decades, an aerospace industry trend in the secondary power distribution concept has been dominated by power electronics technology which includes power converters and Power Control Modules based on Solid State Power Control (SSPC) switching elements. These Power Control Modules, grouped around microprocessor based controllers and combined in a single electronic chassis, have become a backbone of electrical power distribution systems on all major commercial and military transport aircraft. Due to the resistive properties of the semiconductor-based SSPC devices, whose behaviors can be described as nonlinear functions of ambient operating temperature, power distribution system integration with SSPCs is challenged and heavily affected by operating temperatures and power dissipation limits. Although aircraft compartments where Power Control Modules are located are considered temperature and pressure controlled, high ambient operating temperatures are possible and expected.

There are many identical large solid-state switching Multi-Purpose Motor Controllers on board of one of the More Electric Aircrafts (MEA). The controllers drive over twice as many different machines with wide torque and speed ranges. The common motor controllers are installed in a central location. The machines are located at diverse and distant positions. Power is delivered and routed from the controllers to machines via a large network comprising of unshielded feeders and multiplexing units. The controllers are required to produce sine wave voltage output to machines, and draw clean power from the source to meet Power Quality (PQ) and Electromagnetic Interference (EMI) requirements. There are significant aircraft level weight savings with that concept. However, designing such a clean motor controller was a major power density challenge beyond switches, accounting for high torque main propulsion engine start and high speed Cabin Air Compressors.

In modern aircraft power systems, active power converters are promising replacements for transformer rectifier units concerning efficiency and weight. To assess the benefits of active power converters, converter design and optimization should be carefully done under the operation requirements of aircraft applications: electromagnetic interference (EMI) standards, power quality standards, etc. Moreover, certain applications may have strict limits on other converter specifications: weight, size, converter loss, etc. This paper presents the methodology for performance optimization of different active power converters (active front-ends, isolated DC/DC converters and three-phase isolated converters) for aircraft applications. Key methods for power converter component (e.g. inductors, semiconductor devices, etc.) performance optimization and loss calculation are introduced along with the converter optimization procedure.

This paper presents an overview of a project called “Modelling and Simulation Tools for Systems Integration on Aircraft (MISSION)”. This is a collaborative project being developed under the European Union Clean Sky 2 Program, a public-private partnership bringing together aeronautics industrial leaders and public research organizations based in Europe. The provision of integrated modeling, simulation, and optimization tools to effectively support all stages of aircraft design remains a critical challenge in the Aerospace industry. In particular the high level of system integration that is characteristic of new aircraft designs is dramatically increasing the complexity of both design and verification. Simultaneously, the multi-physics interactions between structural, electrical, thermal, and hydraulic components have become more significant as the systems become increasingly interconnected.

In Aerospace Industry, the major challenge is to meet the safety and quality of subsystem / system elements to comply with the standards defined by regulatory authorities for product certification. Engineering test labs are created to provide such precision oriented test platforms ranging from component level to fully integrated test labs/test systems, standalone or distributed network. Even after massive initial capital investment and with the evolution of technologies followed by principles of practice in establishing test facilities, industry is facing open challenges in meeting the performance parameters like productivity, optimum usage, accessibility, monitoring, control and ease of maintenance to list a few. It's very important to standardize the test facilities to optimize time to market and reduce the product cost. This paper discusses test infrastructure architectural factors to setup Seamless, Reliable, Available, Globally Accessible and Remotely Manageable Test Labs.

Auto transformer rectifier units (ATRUs) are commonly used in aircraft applications such as electric actuation for harmonic mitigation due to their high reliability and relative low cost. However, those components and the magnetic filter components associated to it are the major contributors to the overall size and weight of the system. Optimization of the magnetic components is essential in order to minimize weight and size, which are major market drivers in aerospace industry today. This requires knowledge of the harmonic content of the current. This can be obtained by simulation, but the process is slow. In order to enable fast and efficient design space exploration of optimal solutions, an algebraic calculation process is proposed in this paper for multi-pulse ATRUs (e.g. 12-pulse and 18-pulse rectifiers), starting from existing solution proposed for 6 pulse rectifier in the literature.

This paper proposes a method of optimizing aircraft system architectures by considering the efficiencies of each energy conversion step necessary to fulfill the intended function. In addition, these conversion efficiencies need to be evaluated at all critical operating points for the systems involved (e.g. engine, generator, loads, etc.). The methodology starts with examining the energy sources on the aircraft, the energy loads and the energy transfer efficiencies between the sources and the loads. Modern aircraft architecture trends are broadly addressed along with a framework for applying this methodology, but specific aircraft are not analyzed due to the proprietary nature of some of the conversion efficiency data.

This paper addresses the issue of fault diagnosis in the heat exchanger of an aircraft Air Conditioning System (ACS). The heat exchanger cools the air by transferring the heat to the ram-air. Due to a variety of biological, mechanical and chemical reasons, the heat exchanger may experience fouling conditions that reduces the efficiency and could considerably affect the functionality of the ACS. Since, the access to the heat exchanger is limited and time consuming, it is preferable to implement an early fault diagnosis technique that would facilitate Condition Based Maintenance (CBM). The main contribution of the paper is pre-flight fault assessment of the heat exchanger using a combined model-based and data-driven approach of fault diagnosis. A Simulink model of the ACS, that has been designed and validated by an industry partner, has been used for generation of sensor data for various fouling conditions.

In aerospace industry, the concept of Integrated Vehicle Health Management (IVHM) has gained momentum and is becoming need of the hour for entire value chain in the industry. The expected benefits of lesser time for maintenance reduced operating cost and ever busy airports are motivating aircraft manufacturers to come up with tools, techniques and technologies to enable advanced diagnostic and prognostic systems in aircrafts. At present, various groups are working on different systems and platforms for health monitoring of an aircraft e.g. SHM (Structural Health Monitoring), PHM (Prognostics Health Monitoring), AHM (Aircraft Health Monitoring), and EHM (Engine Health Monitoring) and so on. However, these approaches are mostly restricted to federated architecture where faults and failures for standalone line replaceable units (LRUs) are logged inside the unit in fault storage area and are retrieved explicitly using maintenance based applications for fault and failure diagnostics.

Multi core platforms offer high performance at low power and have been deemed as future of size, weight and power constrained applications like avionics safety critical applications. Multi core platforms are widely used in non-real time systems where the average case performance is desired like in consumer electronics, telecom domains. Despite these advantages, multi core platforms (hardware and software) pose significant certification challenges for safety critical applications and hence there has been limited usage in avionics and other safety critical applications. Many multicore platform solutions which can be certified to DO-254 & DO 178B Level A are commercially available. There is a need to evaluate these platforms w.r.t certification requirements before deploying them in the safety critical systems thereby reducing the program risks. This paper discusses the advantages of multi core platforms in terms of performance, power consumption and weight/size.

Today's digital avionics systems leverage the use of the Embedded COTS (Commercial Off The Shelf) hardware to fit the need of small form factor, low power, reduced time to market and reduced development time with efficient use of DO-254 for compliance of product. COTS modules are entering in digital avionics systems such as COM (Computer On Module)/SOM (System On Module)/SIP (System In Package) with huge advancement in semiconductor and packaging industry. In today's scenario COTS are very useful for DAL (Development Assurance Level) C and below as the efforts on compliance for DAL A and B are huge. This paper proposes to use these for DAL A and B as well, where one can get enormous benefit on efforts of compliance and time to market. This paper makes an attempt to explain the current scenario of the Embedded COTS usage in Avionics Systems.

Avionics industry is moving towards more electric & lightweight aircrafts. Electromagnetic effects becomes significantly challenging as materials starts moving towards composite type. Traditional methods for controlling EMC will not be sufficient. This shift increases the complexity of in-flight hardware elements for EMI/EMC control. This paper discusses the need for EMI/EMC Control and brings out the analysis & applicability of various EMI/EMC standards in aerospace, commercial and industrial electronic products, provides comparative study with respect to levels. The study include various sections of DO-160 and applicable guidelines for controlling EMI/EMC with respect to LRU (Line Replaceable Unit) & wire/cable harnesses. Also presents guidelines with respect to shielding of components, selection of components, grounding schemes, filter topologies and layout considerations.

The Aircraft System Health Management (ASHM) tool is a UTC developed web application that provides access to Aircraft Condition Monitoring Function (ACMF) reports and Flight Deck Effects (FDE) records for Boeing 787®, A320®, and A380® aircraft. The tool was built with a flexible architecture to field a range of off-board diagnostics and prognostics modules designed to transform an abundance of data into actionable and timely knowledge about fleet health. This paper describes the system architecture and implementation with a focus on “lessons learned” in applying diagnostic and prognostics algorithms to available fleet data. Key topics include ensuring analytic robustness, design for cross-enterprise collaboration and defining a workable approach to testing, validating and deploying prognostics and diagnostics models with various degrees of complexity. A case study is provided related to fluid leak detection within an environmental control subsystem.