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Modern aircraft systems employ numerous processors to achieve system functionality. In particular, engine controls and power distribution subsystems rely heavily on software to provide safety-critical functionality, and are expected to move toward multicore architectures. The computing hardware-layer of avionic systems must be able to execute many concurrent workloads under tight deterministic execution guarantees to meet the safety standards. Single-chip multicores are attractive for safety-critical embedded systems due to their lightweight form factor. However, multicores aggressively share hardware resources, leading to interference that in turn creates non-deterministic execution for multiple concurrent workloads. We propose an approach to remove on-chip interference via a set of methods to spatio-temporally partition shared multicore resources.

The exponential increase in the number of aircrafts and air travelers has triggered new innovations which aim to make airline services more reliable and consumer friendly. Quick and efficient maintenance actions with minimum downtime are the need of the hour. Areas that have a large potential for improvement in this regard are the real time use of diagnostic data, filtering/elimination of nuisance faults and machine learning capabilities with respect to maintenance actions. Although, numerous LRUs installed on the aircraft generate massive amounts of diagnostic data to detect any possible issue or LRU failure, it is seldom used in real time. The turnaround time for LRU maintenance can be greatly reduced if the results of the diagnostics conducted during LRU normal operation is relayed to ground stations in real-time. This enables the maintenance engineers to plan ahead and initiate maintenance actions well before the aircraft lands and becomes available for maintenance.

Formal Methods, and in particular Model Checking, are seeing an increasing use in the Aerospace domain. In recent years, Formal Methods are now commonly used to verify systems and software and its correctness as a way to augment traditional methods relying on simulation and testing. Recent updates to the relevant Aerospace regulations (e.g. DO178C, DO331 and DO333) now have explicit provisions for utilization of models and formal methods. At the system level, Model Checking has seen more limited uses due to the complexity and abstractions needed. In this paper we propose several methods to increase the capability of applying Model Checking to complex Aerospace Systems. An aircraft electrical power system is used to highlight the methodology. Automated model-based methods such as Cone of Influence and Timer Abstractions are described. Results of those simplifications, in combination with traditional Assume-Guarantee approaches will be shown for the Electric Power System application.

The complexity of software development is increasing unprecedentedly with every next generation of aircraft systems. This requires to adopt new techniques of software design and verification that could optimize the time and cost of software development. At the same time these techniques need to ensure high quality of software design and safety compliance to regulatory guidelines like DO-178C [1] and its supplements DO-330[2] and DO-331[3]. To arrive at new technologies one has to evaluate the alternate methods available for software design by developing models, integration of models, auto-code generation, auto test generation and also the performance parameters like time, effort, reuse and presentation needs to be evaluated. We have made an attempt to present summary of alternate design concept study, and edge of MBD over other design techniques.

Aircraft weight and center of mass are two critical design and operational parameters that have to be within a design envelope to ensure a safe and efficient operation of aircraft. Previous efforts to accurately determine aircraft weight and center of mass before takeoff using landing gear shock strut pressures have failed due to the distortion of measured pressures by shock strut seal friction. Currently, aircraft loading process is controlled with loading sheets and passenger/cargo weight estimation as there are no online measurement systems that can accurately and efficiently estimate aircraft weight and determine the center of mass location before takeoff. However, errors in loading sheets, shifting cargo and errors in weight estimation could lead to incorrect loading of aircraft and, consequently, increase the risk of accidents, particularly in cargo flights.

Cloud phase discrimination, coupled with measurements of liquid water content (LWC) and ice water content (IWC) as well as the detection and discrimination of supercooled large droplets (SLD), are of primary importance in aviation safety due to several high-profile incidents over the past two decades. The UTC Aerospace Systems Optical Ice Detector (OID) is a prototype laser sensor intended to discriminate cloud phase, to quantify LWC and IWC, and to detect SLD and differentiate SLD conditions from those of Appendix C. Phase discrimination is achieved through depolarization scattering measurements of a circularly polarized laser beam transmitted into the cloud. Optical extinction measurements indicate the liquid and ice water contents, while the differential backscatter from two distinct probe laser wavelengths implies an effective droplet size. The OID is designed to be flush-mounted with the aircraft skin and to sample the air stream beyond the boundary layer of the aircraft.

Carrier Injection Sensorless (CIS) rotor position estimation for electric machines depends on the rotor saliency “seen” from the stator terminals. Compared to permanent magnet and induction machines, wound field synchronous machine rotor saliency characteristics are more complex. At typical carrier frequencies subtransient characteristics dominate. Injecting positively rotating carrier voltages at the stator terminals of a machine having rotor saliency produces both positively and negatively rotating carrier currents. The impedances relating currents to injected carrier voltages are derived from the dq reference frame synchronous machine model. Analytical results are compared to simulation and limited test results for an aircraft starter/generator.

Avionics industry is moving towards fly-by wire aircrafts with less reliance on mechanical systems leading to increase in the complexity of in-flight hardware elements. RTCA/DO-254 and EUROCAE ED-80 plays a vital role in the design assurance of airborne electronic hardware. RTCA/ DO-254 and EUROCAE ED-80 are the industry standards for Design Assurance Guidance for Airborne Electronic Hardware. The two different agencies FAA and EU regulate and apply this design assurance guidance to the regulatory law in CFR and EASA CS respectively. This paper discusses the need for DO-254 /ED-80 certification in Aerospace industry, the advantages and benefits to the avionics manufacturers. The paper presents the study made on similarities and differences between DO-254/ED-80.

Airport environments consist of several moving objects both in the air and on the ground. In air moving objects include aircraft, UAVs and birds etc. On ground moving objects include aircraft, ground vehicles and ground personnel etc. Detecting, classifying, identifying and tracking these objects are necessary for avoiding collisions in all environmental situations. Multiple sensors need to be employed for capturing the object shape and position from multiple directions. Data from these sensors are combined and processed for object identification. In current scenario, there is no comprehensive traffic monitoring system that uses multisensor data for monitoring in all the airport areas. In this paper, for explanation purposes, a hypothetical airport traffic monitoring system is presumed that uses multiple sensors for avoiding collisions.

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.

Under a NASA-sponsored technology development project, a multi-disciplinary team consisting of industry, academia, and government organizations lead by Hamilton Sundstrand is developing an amine-based humidity and CO2 removal process and prototype equipment for Vision for Space Exploration (VSE) applications. Originally this project sought to research enhanced amine formulations and incorporate a trace contaminant control capability into the sorbent. In October 2005, NASA re-directed the project team to accelerate the delivery of hardware by approximately one year and emphasize deployment on board the Crew Exploration Vehicle (CEV) as the near-term developmental goal. Preliminary performance requirements were defined based on nominal and off-nominal conditions and the design effort was initiated using the baseline amine sorbent, SA9T.

Under a NASA sponsored technology development activity, Hamilton Sundstrand has designed, fabricated, tested and delivered a prototype solid amine-based carbon dioxide (CO2) and water (H2O) vapor removal system sized for Extravehicular Activity (EVA) operation. The prototype system employs two alternating and thermally-linked solid amine sorbent beds to continuously remove CO2 and H2O vapor from a closed environment. While one sorbent bed is exposed to the vent loop to remove CO2 and water vapor, the other bed is exposed to a regeneration circuit, defined as either vacuum or an inert sweep gas stream. A linear spool valve, coupled directly to the amine canister assembly, is utilized to simultaneously divert the vent loop flow and regeneration circuit flow between the two sorbent beds.

Under a NASA-sponsored technology development project, a multi-disciplinary team consisting of industry, academia, and government organizations led by Hamilton Sundstrand is developing an amine based humidity and carbon dioxide (CO2) removal process and prototype equipment for Vision for Space Exploration (VSE) applications. This system employs thermally linked amine sorbent beds operating as a pressure swing adsorption system, using the vacuum of space for regeneration. The prototype hardware was designed based on a two fault tolerant requirement, resulting in a single system that could handle the metabolic water and carbon dioxide load for a crew size of six. Two, full scale prototype hardware sets, consisting of a linear spool valve, actuator and amine sorbent canister, have been manufactured, tested, and subsequently delivered to NASA JSC. This paper presents the design configuration and the pre-delivery performance test results for the CAMRAS hardware.

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.

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.

Atmospheric monitoring is one of the most important elements in life support aboard U.S. Navy nuclear submarines. The Central Atmosphere Monitoring Systems have reliably served the U.S. Navy by accurately monitoring life gases and contaminants for nearly 30 years. However, as new knowledge of chemical effects on human health increases, the demand for monitoring additional compounds in these closed environments is also increasing. As a result, expanded capability for detecting trace compounds becomes more important and a next-generation monitoring system is warranted. In addition to improved analytical performance, the trend for submarine operation is to increase the degree of distribution and automation to minimize the resources needed for operation and maintenance. It is therefore desirable to incorporate the monitoring instrumentation into the atmosphere control system to provide real-time feedback and automated control.

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.

This paper addresses the issues of data reduction, visualization, clustering and classification for fault diagnosis and prognosis of the Liquid Cooling System (LCS) in an aircraft. LCS is a cooling system that consists of a left and a right loop, where each loop is composed of a variety of components including a heat exchanger, source control units, a compressor, and a pump. The LCS data and the fault correlation analysis used in the paper are provided by Hamilton Sundstrand (HS) - A United Technologies Company (UTC). This data set includes a variety of sensor measurements for system parameters including temperatures and pressures of different components, along with liquid levels and valve positions of the pumps and controllers. A graphical user interface (GUI) is developed in Matlab that facilitates extensive plotting of the parameters versus each other, and/or time to observe the trends in the 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.

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.