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Technical Paper

ONICE2D and DROP3D SLD Capability Assessment

2011-06-13
2011-38-0088
In 1994, an ATR-72 crashed at Roselawn, Indiana, USA. It has been speculated that accident was due to Supercooled Large Droplet (SLD) icing. This accident led to a modification of the regulation rules with the definition of the Appendix O which includes freezing drizzle and freezing rain icing conditions. The associated NPRM (Notice of Proposed Rule Making) has been distributed to industry for comments on 29th June 2010 and could be applicable by beginning 2012. In order to comply with this new rule, the simulation tools, as Acceptable Means of Compliance, have to be improved and validated for these conditions. The paper presents the work performed within Airbus to review, improve and assess simulation tools capability to accurately predict physical phenomena related to SLD. It focuses in particular on splashing and bouncing phenomena which have been highlighted as the first order effects.
Technical Paper

Future Concept of Operations: The Airbus ADS-B Perspective

2010-09-30
2010-01-1660
This paper describes the Airbus plans to use ADS-B in the future concept of operations in both the European SESAR and the US NEXTGEN concepts of operations. It details the different steps that are currently considered by Airbus roadmap to deploy ADS-B services and functions. In particular, the following points are described: Use of ADS-B OUT in Non Radar Airspace Use of ADS-B IN and the associated Airbus functions to offer a better Air Traffic Situation Awareness (ATSAW) package: the various applications for airborne, in trail climb/descent procedures or enhanced visual acquisition are particularly detailed. Use of ADS-B for the future Spacing function as currently considered in the initial ASAS implementation for SESAR: the three “Remain Behind”, “Merge at Waypoint then Remain behind” and the “Heading then merge behind” applications are explained.
Technical Paper

On-line Estimation of Longitudinal Flight Parameters

2011-10-18
2011-01-2769
The introduction of Fly-By-Wire (FBW) and the increasing level of automation contribute to improve the safety of civil aircraft significantly. These technological steps permit the development of advanced capabilities for detecting, protecting and optimizing A/C guidance and control. Accordingly, this higher complexity requires extending the availability of aircraft states, some flight parameters becoming key parameters to ensure a good behaviour of the flight control systems. Consequently, the monitoring and consolidation of these signals appear as major issues to achieve the expected autonomy. Two different alternatives occur to get this result. The usual solution consists in introducing many functionally redundant elements (sensors) to enlarge the way the key parameters are measured. This solution corresponds to the classical hardware redundancy, but penalizes the overall system performance in terms of weight, power consumption, space requirements, and extra maintenance needs.
Technical Paper

Innovation Readiness: Past and Current Drivers in Aeronautical Engineering

2011-10-18
2011-01-2501
This paper proposes a rearview on aeronautical innovation, addresses some 2000-2010 new products, and suggests elements of future vision, serving passengers aspirations. Over 100 years, aeronautics brilliantly domesticated flight: feasibility, safety, efficiency, international travel, traffic volume and noise, allowing airlines to run a business, really connecting real people. Despite some maturations, new developments should extend the notion of passenger service. So far, turbofans became silent and widebodies opened ‘air-bus’ travel for widespread business, tourism or education. Today airports symbolize cities and vitalize regional economies. 2000-2010 saw the full double-decker, the new eco-friendly freighter and electronic ticketing. In technology, new winglets and neo classical engines soon will save short-range blockfuel. In systems and maintenance, integrated modular avionics and onboard data systems give new flexibility, incl by data links to ground.
Technical Paper

Advanced Diagnosis for Sustainable Flight Guidance and Control: The European ADDSAFE Project

2011-10-18
2011-01-2804
The state-of-practice for aircraft manufacturers to diagnose guidance & control faults and obtain full flight envelope protection at all times is to provide high levels of dissimilar hardware redundancy. This ensures sufficient available control action and allows performing coherency tests, cross and consistency checks, voting mechanisms and built-in test techniques of varying sophistication. This hardware-redundancy based fault detection and diagnosis (FDD) approach is nowadays the standard industrial practice and fits also into current aircraft certification processes while ensuring the highest level of safety standards. In the context of future “sustainable” aircraft (More Affordable, Smarter, Cleaner and Quieter), the Electrical Flight Control System (EFCS) design objectives, originating from structural loads design constraints, are becoming more and more stringent.
Technical Paper

Characterization of Hypervisors for Security-Enhanced Avionics Applications

2011-10-18
2011-01-2805
Traditionally, software in avionics has been totally separated from open-world software, in order to avoid any interaction that could corrupt critical on-board systems. However, new aircraft generations need more interaction with off-board systems to offer extended services, which makes these information flows potentially dangerous. In a previous work, we have proposed the use of virtualization to ensure dependability of critical applications despite bidirectional communication between critical on-board systems and untrusted off-board systems. We have developed a test bed to assess the performance impact induced by the use of virtualization. In this work, various configurations have been experimented that range from a basic machine without an OS up to the complete architecture featuring a hypervisor and an OS running in a virtual machine. Several tests (computation, memory, network) are carried out, and timing measures are collected on different hypervisors.
Technical Paper

Flight Parameter Estimation for Augmented Flight Control System Autonomy

2011-10-18
2011-01-2801
In the framework of the aircraft global optimization, for future and upcoming programs, current research interests include more Electrical Flight Control System (EFCS) autonomy for a more easy-to-handle aircraft. A possible solution is to increase the number of redundant flight parameter sensors but to the detriment of the aircraft weight and so to the cost and performances. This paper proposes an algorithm using PLS (Partial Least Squares) to estimate a flight parameter from independent sensor measurements. The estimates are then used as so-called “software” or “virtual” sensors, allowing aircraft weight saving. This algorithm is based on an iterative processing and thus can be used in real time in the embedded flight control computer. Furthermore, the resulting flight parameter estimates can be used to detect failures. Different detection strategies are proposed and results show that this method can lead to robust detections.
Technical Paper

Evaluation of Small Scale Icing Tunnel Test Results

2007-09-24
2007-01-3328
A test has been performed using a scaled aircraft wing section in an icing tunnel facility. The model had an electro-thermal ice protection system installed. The tests performed considered both anti-icing and de-icing modes of operation. The results have been assessed using numerical codes and the effect of model scaling has been considered. The non-scaled skin thickness of the model was found to modify the predicted behaviour of a full-scale installation, predominantly due to lateral conduction effects. The extent of this has been assessed and recommendations are made as to the performance that may be expected at full-scale.
Technical Paper

Minimizing Impact on Climate in Aircraft Design

2007-09-17
2007-01-3807
A two-level approach for the consideration of climate change in the aircraft design process is proposed. Depending on the availability of suitable atmospheric metrics, the methodology has been put into practice only recently. The assessment of technology and design changes is enabled with regard to the impact of aircraft on climate. First example applications show that the methodology is not yet ready for full industrial application, but that it can give useful hints for the orientation of aircraft concepts for the future aviation system.
Technical Paper

Aeronautical Fuel Cell System Application and Associated Standardization Work

2006-11-07
2006-01-3093
Airbus is a leading aircraft manufacturer with the position as technology driver and a distinct customer orientation, broad commercial know-how and high production efficiencies. It is constantly working on further and new development of its products from ecological and economical points of view. Fuel Cell Systems (FCS) on board of an aircraft provide a good opportunity to address both aspects. Based on existing and upcoming research results it is necessary to find trend-setting measures for the industrial implementation and application of this technology. Past and current research efforts have shown good prospects for the industrial implementation and application of the fuel cell technology. Being an efficient source of primarily electric power the fuel cell would be most beneficial when used in conjunction with electrical systems.
Journal Article

A Model-based Solution to Robust and Early Detection of Control Surface Runaways

2011-10-18
2011-01-2803
This paper discusses the design of a model-based fault detection scheme for robust and early detection of runaways in aircraft control surfaces servo-loop. The proposed scheme can be embedded within the structure of in-service monitoring systems as a part of the Flight Control Computer (FCC) software. The final goal is to contribute to improve the performance detection of unanticipated runaway faulty profiles having very different dynamic behaviors, while retaining a perfect robustness. The paper discusses also the tradeoffs between adequacy of the technique and its implementation level, industrial validation process with Engineering support tools, as well as the tuning aspects. The proposed methodology is based on a combined data-driven and system-based approach using a dedicated Kalman filtering. The technique provides an effective method ensuring robustness and good performance (well-defined real-time characteristics and well-defined error rates).
Technical Paper

Mathematical Model of Water Contamination in Aircraft Fuel Tanks

2011-10-18
2011-01-2540
Water is a contaminant that can lead to fuel system icing, microbial contamination, corrosion and fuel quantity gauging problems and therefore an efficient water management system is required in order to maximise the performance of an aircraft's fuel system. This paper describes a time-transient aircraft fuel tank model with water contamination, due to the principal mechanisms of dissolution, suspension, condensation and transportation. The tank model presented is a component of the NEPTUNE fuel system model which was developed for Airbus using the A380 as an example aircraft. A description of the physics of water contaminated fuel is given and of how this has been incorporated into a mathematical model of an aircraft fuel tank. A modular approach is demonstrated which enables interconnecting fuel tanks to be configured in larger systems in a flexible and easily understood manner.
Technical Paper

Sensitivity of SAE Total Pressure Intake Distortion Descriptors to Pressure Fluctuations at the Engine-Intake Interface Plane

2011-10-18
2011-01-2544
A methodology to evaluate the sensitivity of total pressure intake distortion descriptors defined by SAE ARP 1420 to individual pressure fluctuations in the Aerodynamic Interface Plane -AIP- has been developed. Individual pressure fluctuations were simulated as a white noise using a random number generator with a Gaussian distribution of known standard deviation. Monte Carlo experiments were performed perturbing different steady total pressure patterns on the AIP with random signals of different RMS values. Instantaneous distortion descriptors were calculated and statistically characterized. General correlations were obtained applying maximum value statistics to relate the maximum expected distortion increment to the RMS of the individual pressure fluctuations, the mean total pressure on the AIP and the number of samples.
Technical Paper

Model-Based Safety Assessment for the Three Stages of Refinement of the System Development Process in ARP4754A

2011-10-18
2011-01-2548
Model Based Safety techniques have been developed for a number of years, though the models have not been customised to help address the safety considerations/ actions at each refinement level. The work performed in the MISSA Project looked at defining the content of “safety models” for each of the refinement levels. A modelling approach has been defined that provides support for the initial functional hazard analysis, then for the systems architectural definition level and finally for the systems implementation level. The Aircraft functional model is used to apportion qualitative and quantitative requirements, the systems architectural level is used to perform a preliminary systems safety analysis to demonstrate that a system architecture can satisfy qualitative and quantitative requirements.
Technical Paper

On the Synthesis and Validation of Safety Assessment Models

2011-10-18
2011-01-2549
Safety is one of the most important aspects of which we are concerned with in the field of aerospace-systems development. There are a variety of safety assessment activities that are performed throughout a system's lifecycle. Multiple interrelated safety analysis artifacts are generated from the process. However, requirements and guidance for the synthesis and validation of the results of this analysis are insufficient and are not explicit. In traditional system development processes, certification coordination, safety assessment, requirements validation, and implementation verification are generally treated as supporting processes, which are concurrent and interactively dependent throughout the iterative development of a system. In SAE ARP4754A, these processes are stressed as integral processes with traceability between safety requirements and the dependencies between safety assessment activities highlighted as an important concern.
Technical Paper

Development of a High Temperature Power Module Technology with SiC Devices for High Density Power Electronics

2011-10-18
2011-01-2620
This paper presents the development of a high density packaging technology for wide band gap power devices, such as silicon carbide (SiC). These devices are interesting candidates for the next aircraft power electronic converters. Effectively they achieve high switching frequencies thanks to the low losses level. High switching frequencies lead to reduce the passive components size and to an overall weight reduction of power converters. Moreover, SiC devices may enable operation at junction temperatures around 250°C. The cooling requirement is much less stringent than for usual Si devices. This might considerably simplify the cooling system, and reduce the overall weight. To achieve the integration requirements for SiC devices, classical wire bonding interconnection is replaced by a stacked packaging using bump interconnection technologies, called sandwich. These technologies offer two thermal paths to drain heat out and present more power integration possibilities.
Technical Paper

Eclipse Framework for an Integrated IMA Tool Chain

2011-10-18
2011-01-2635
Development for the Integrated Modular Avionics (IMA) platform is complex owing to the variety of equipment, vendors and non-uniform tools. The development should be simplified by a model-based harmonized tool environment by means of an integrated set of tools of different type, origin and purpose. Eclipse's flexible and modular architecture seems adequate as a framework for such a harmonized IMA development environment. This article evaluates how Eclipse could practically be utilized for this purpose. The IMA process and development requirements like concurrency, different process roles, and multiple tools are mapped to the Eclipse framework. In addition, open-source extensions for model-based engineering and application development are integrated in the tools chain. In order to test the performance, openness and compatibility of Eclipse and the tools from the IMA development process, six current and future tools are integrated into a prototype of a common Eclipse instance.
Technical Paper

How Tools and Process Improved Diagnostic and Prognostic Reaction Time

2015-09-15
2015-01-2589
Modern aircraft, such as A380 or A350 for Airbus, are very well connected in flight to ground stations through wireless communications. For maintenance and operations purpose, the aircraft is programmed to send regularly information such as flight reports based on the BITE messages (Built-In Test Equipment) or standard reports based on the value of physical parameters. Moreover, Airbus is capable of sending requests (called uplinks) to the aircraft to retrieve the value of different parameters in almost real-time. This ability, associated with adequate process, improves significantly the reaction time of the diagnostic and prognostic solutions that Airbus can provide to its customers. Traditionally Health Monitoring is considered useful when the Potential to Functional failure (P-F) interval is greater than one flight cycle.
Technical Paper

Ranking of Thick Ice Shapes Based on Numerical Simulation for Certification

2019-06-10
2019-01-1944
The objective of this paper is to present a numerical method to rank thick ice shapes for aircraft by comparing the ice accretion effects for different icing scenarios in order to determine the more critical ice shape. This ranking allows limiting the demonstration of the aerodynamic characteristics of the aircraft in iced condition during certification to a reduced number of ice shapes. The usage of this numerical method gives more flexibility to the determination of the critical ice shapes, as it is not dependent of the availability of physical test vehicles and/or facilities. The simulation strategy is built on the Lattice Boltzmann Method (LBM) and is validated based on a representative test case, both in terms of aircraft geometry and ice shapes. Validation against existing experimental results shows the method exhibits an adequate level of reliability for the ranking of thick ice shapes.
Technical Paper

Applying a Concept for Robot-Human Cooperation to Aerospace Equipping Processes

2011-10-18
2011-01-2655
Significant effort has been applied to the introduction of automation for the structural assembly of aircraft. However, the equipping of the aircraft with internal services such as hydraulics, fuel, bleed-air and electrics and the attachment of movables such as ailerons and flaps remains almost exclusively manual and little research has been directed towards it. The problem is that the process requires lengthy assembly methods and there are many complex tasks which require high levels of dexterity and judgement from human operators. The parts used are prone to tolerance stack-ups, the tolerance for mating parts is extremely tight (sub-millimetre) and access is very poor. All of these make the application of conventional automation almost impossible. A possible solution is flexible metrology assisted collaborative assembly. This aims to optimise the assembly processes by using a robot to position the parts whilst an operator performs the fixing process.
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