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Technical Paper

A350XWB Icing Certification Overview

2015-06-15
2015-01-2111
The intent of this paper is to provide a general overview of the main engineering and test activities conducted in order to support A350XWB Ice and Rain Protection Systems certification. Several means of compliance have been used to demonstrate compliance with applicable Certification Basis (CS 25 at Amendment 8 + CS 25.795 at Amendment 9, FAR 25 up to Amendment 129) and Environmental protection requirements. The EASA Type Certificate for the A350XWB was received the 30th September 2014 after 7 years of development and verification that the design performs as required, with five A350XWB test aircraft accumulating more than 2600 flight test hours and over 600 flights. The flight tests were performed in dry air and measured natural icing conditions to demonstrate the performance of all ice and rain protection systems and to support the compliance demonstration with CS 25.1419 and CS25.21g.
Journal Article

ARP4754A/ ED-79A - Guidelines for Development of Civil Aircraft and Systems - Enhancements, Novelties and Key Topics

2011-10-18
2011-01-2564
ARP4754A/ED-79A guidelines addresse the development cycle for aircraft and systems that implement aircraft functions. The current trend in system design is an increasing level of integration between aircraft functions and the systems that implement them. While there can be considerable value gained when integrating systems with other systems, the increased complexity yields increased possibilities for errors, particularly with functions that are performed jointly across multiple systems. Following the Aviation Rulemaking Advisory Committee (ARAC) recommendations to respond to this increased integration which referenced ARP4754/ED-79 in advisory materials for compliance to 14CFR/CS 25.1309 (see AMC 25.1309, published in 2002 and AC25.1309-Arsenal draft) the use of ARP4754A/ED79A in aircraft certification has become increasingly widespread.
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

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.
Journal Article

Blind Bolts Developments

2011-10-18
2011-01-2755
There is an ever growing demand for blind fastener in the aerospace industry. This demand is driven not only by the advantages of single sided installation, but also by the potential to fully automate their installation process. Blind fasteners can easily be integrated with innovative end-effectors that combine drilling, installation and inspection systems, enabling the reduction of process cycle times and their associated cost savings. Clearly the advantages of single sided installation are a key benefit, but it cannot be forgotten that currently the mechanical performance of these systems is reduced compared with conventional threaded or swaged parallel shank fasteners. There are other important drawbacks existing around them which could penalise significantly the optimised design and performance of the structures. Specific key characteristics that take into account some of these drawbacks have been established by Airbus which will be referenced in this paper.
Book

Care and Repair of Advanced Composites, Second Edition

2005-06-22
This second edition has been extensively updated to keep pace with the growing use of composite materials in commercial aviation. A worldwide reference for repair technicians and design engineers, the book is an outgrowth of the course syllabus that was developed by the Training Task Group of SAE's Commercial Aircraft Composite Repair Committee (CACRC) and published as SAE AIR 4938, Composite and Bonded Structure Technician Specialist Training Document. Topics new to this edition include: Nondestructive Inspection (NDI) Methods Fasteners for Composite Materials A Method for the Surface Preparation of Metals Prior to Adhesive Bonding Repair Design Although this book has been written primarily for use in aircraft repair other applications including marine and automotive are also covered.
Technical Paper

Combination of Experimental and Computational Approaches to A320 Wing Assembly

2017-09-19
2017-01-2085
The paper is devoted to the simulation of A320 wing assembly on the base of numerical experiments carried out with the help of ASRP software. The main goal is to find fasteners’ configuration with minimal number of fastening elements that provides closing of admissible initial gaps. However, for considered junction type initial gap field is not known a priori though it should be provided as input data for computations. In order to resolve this problem the methodology of random initial gap generation based on available results of gap measurements is developed along with algorithms for optimization of fasteners' configuration on generated initial gaps. Presented paper illustrates how this methodology allows optimizing assembly process for A320 wing.
Technical Paper

Dimensional Analysis to Parameterise Ice Accretion on Mesh Strainers

2011-10-18
2011-01-2795
Water is always present in jet fuel, usually in a mixture of forms. At very low temperatures this phenomenon can lead to the formation of ice crystals within the aircraft fuel system, which can then stay in suspension within the entire volume of fuel. Pumps within the fuel system transfer fuel around the system. Pumps such as boost pumps that are typically used in fuel systems are protected by a weave type filter mesh at the inlet. Ice accretion on the surface of this mesh has operational implications as it can cause non optimal fuel flow. In this investigation, two fundamental tools are being used: 1) a high fidelity MATLAB model of a mesh strainer, pick-up line and pump, and 2) a test rig of the modelled system. The model is being used to investigate fuel system performance when exposed to fuel containing water/ice contaminants at cold temperatures.
Technical Paper

EMA Aileron COVADIS Development

2011-10-18
2011-01-2729
In the frame of the COVADIS project (flight control with distributed intelligence and systems integration) supported by the DPAC and where Airbus and Sagem are partners, an electromechanical actuator (EMA) developed and produced by Sagem (SAFRAN group) flew for the first time in January 2011 as an aileron primary flight control of the Airbus A320 flight test Aircraft. With this new type of actuator, in the scope of the preparation of the future Airbus Aircraft, the perspectives of using EMA technologies for the flight control systems is an important potential enabler in the more electrical aircraft. The paper deals with the development phase of this actuator from the definition phase up to the flight tests campaign. It is focused on : COVADIS project context (flight control with distributed intelligence and systems integration), The challenges of the definition phase, Test results presentation (ground and flight).
Technical Paper

Eco-efficient Materials for Aircraft Application

2011-10-18
2011-01-2742
Due to the importance of fulfilling the actual and upcoming environmental legislation, it is an Airbus main target to develop eco-efficient materials. Under consideration of the economical effects, these processes will be implemented into the production line. This paper gives an overview of Airbus and its partners research work, the results obtained within the frame of the European funded, integrated technology demonstrator (ITD) ECO Design for Airframe. This ITD is part of the joint technology initiative Clean Sky. Developments with different grade of maturity from “upstream” as the investigation of materials from renewable recourses up to materials now in use in production as low volatile organic compounds cleaner are under investigation. As a basis for future eco-efficient developments an approach for a quantitative life cycle assessment will be demonstrated.
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

Extended Non-Destructive Testing of Composite Bonds

2011-10-18
2011-01-2514
Composite materials are increasingly being used in the manufacturing of structural components in aeronautics industry. A consequent light-weight design of CFRP primary structures requires adhesive bonding as the optimum joining technique but is limited due to a lack of adequate quality assurance procedures. The successful implementation of a reliable quality assurance concept for adhesive bonding within manufacturing and in-service environments will provide the basis for increased use of lightweight composite materials for highly integrated aircraft structures thus minimizing rivet-based assembly. The expected weight saving for the fuselage airframe is remarkable and therefore the driver for research and development of key-enabling technologies. The performance of adhesive bonds mainly depends on the physico-chemical properties of adherend surfaces.
Technical Paper

Fixturing and Tooling for Wing Assembly with Reconfigurable Datum System Pickup

2011-10-18
2011-01-2556
The aerospace manufacturing sector is continuously seeking automation due to increased demand for the next generation single-isle aircraft. In order to reduce weight and fuel consumption aircraft manufacturers have increasingly started to use more composites as part of the structure. The manufacture and assembly of composites poses different constraints and challenges compared to the more traditional aircraft build consisting of metal components. In order to overcome these problems and to achieve the desired production rate existing manufacturing technologies have to be improved. New technologies and build concepts have to be developed in order to achieve the rate and ramp up of production and cost saving. This paper investigates how to achieve the rib hole key characteristic (KC) in a composite wing box assembly process. When the rib hole KC is out of tolerances, possibly, the KC can be achieved by imposing it by means of adjustable tooling and fixturing elements.
Journal Article

Flexible Tooling for Wing Box Rib Clamping and Drilling

2011-10-18
2011-01-2639
Currently the wing box rib assembly process requires the manual location and temporary fixing of components within product specific jig or fixtures for drilling. After drilling and reaming, parts are separated, cleaned, deburred prior to adding sealant, reclaiming and final bolting, but this may significantly increase cost, manufacturing lead-time, reduces flexibility and cannot usually be economically modified for use on other aircraft types. Due to potential increase in demand for the next generation single isle aircraft, existing tooling solutions have to be improved and new technologies have to be developed. This paper describes the development and testing of flexible tooling to provide clamping and support for drilling wing box ribs to mating rib posts within a restricted environment. Results are presented along with a discussion of the problems that may be encountered during clamping trials.
Technical Paper

Flight Test Identification Methods for Loads Models and Applications

2011-10-18
2011-01-2763
The Loads discipline contributes to the aircraft structural design by delivering shear, moment and torque (SMT, loads) all across the airframe resulting from application of aircraft airworthiness requirements as laid down in the CS 25/FAR 25 regulations and in some domestic ones. Loads computation considers the maneuver and gust conditions prescribed therein as well as other special design conditions. It is based on very detailed modeling, accounting for aerodynamics in all configurations, mass properties, flexibility of the airframe, flight control laws and retarded laws, hydraulic actuation, and specification of flight control system failure conditions. The resulting shear loads are processed and refined (e.g. nodal loads) and taken into account by the stress department for structural design.
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

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

Innovative Jet Pump Ice Protection System for A400M

2015-06-15
2015-01-2136
A system has been designed for the A400M wherein engine air intake ice protection is provided by hot air bled from the engine cooled by air from inside the nacelle with a jet pump. Two variants of the system were developed. The first had an active temperature and pressure control downstream of the jet pump, and the second was without temperature control. Maximum temperature was a constraint for the design of the system since the engine air intake is manufactured in aluminum. In addition, several other constraints appeared during the detailed design of the system; the tight space allocation inside the nacelle limited the length of the jet pump, the low temperature provided by the engine bleed in flight idle limited the secondary flow used to cool the engine bleed, and the complex air distribution needed to supply air to the intake areas.
Technical Paper

Interface Management in Wing-Box Assembly

2011-10-18
2011-01-2640
Gaps between structural components have been a common problem since the start of aviation. This has usually been caused by the manufacturing tolerances of the components in question not being sufficiently tight. An example where such issues arise is in the assembly of a wing skin to rib feet to form an aircraft wing-box, where it is commonly found that, whilst some rib feet are in contact with the wing skin, others are spaced from it. Yet a strong connection between the wing skin and the rib feet is important to maintain the structural strength of the wing-box. To eliminate the existing gaps, the current approach, used in many manufacturing production lines, involves filling in the gaps to the required shape by applying liquid or solid shim to the rib feet. This is a relatively long and expensive process. To overcome these current inherent difficulties in interface management, a method to eliminate the shimming requirement between component interfaces is presented.
Journal Article

Optimal Control to Recover a Safe Situation from Low/High-Energy Situation in Approach

2011-10-18
2011-01-2618
The main study illustrated in this paper deals with the computation of commands which allow an aircraft to recover a nominal energy trajectory from a low/high energy state during the approach phase. The commands taken into account in this paper are the slat/flap aerodynamic control surfaces which allow the aircraft to maintain the best lift performance for low velocities during the approach phase. In this study, it is supposed that the aircraft maintains a known vertical trajectory, simplified by a constant ground slope, while no engines and airbrakes are used. A non-linear optimization approach is studied in this paper and two methods are tested: a) Hermite-Simpson, trapezoidal collocation methods, b) Sequential numerical integration method. These different methods are tested and simulation results are given for comparison, with different initial velocities permitting to change the initial energy state.
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