Avionics 2001

Citation

(2002), "Avionics 2001", Aircraft Engineering and Aerospace Technology, Vol. 74 No. 2. https://doi.org/10.1108/aeat.2002.12774bac.001

Avionics 2001

The ERA Conference held in Bristol addressed a variety of interesting topics and was supported by international companies and organisations whose expertise was in the forefront of the presentations. The conference was divided into four sessions, the first opening paper being Avionics Development – Changing Technology for Changing Problems, by ERA Technology and North Atlantic Instruments, Europe. The paper looks at the lessons learnt and puts into perspective the significant developments in electronics and civil avionics. It shows how the different business and technology drivers have shaped todays avionics industry. In the 1970s the drivers were the advances in technology arising from military developments, coupled with improvements in aeronautics leading to larger aircraft and the phenomenal growth in long-haul flights needing better aircraft availability.

In order to meet these requirements, the completely new system architecture of the 1980s brought their own challenges of standardisation and certification. For the 1990s, the challenge arose from the end the Cold War and subsequent loss of the availability of military qualified components. This loss resulted in the relatively small sector avionics market becoming reliant upon a massive and highly volatile, short-filed consumer market for the components needed for Integrated Modular Avionics (IMA).

This contribution also outlines the lessons, sometimes painful, that industry, suppliers and customers, have had to learn when providing avionics systems to meet customers expectations in a rapidly changing commercial environment. By revising the lessons learnt, the paper raises the awareness of newcomers in the industry of past issues that often are the same old problem re-emerging in a different guise. Particular attention is given in the concluding part of the paper to ensure that there is an understanding of the overall system requirements; that the timescale for developing a standard must be less than the development timescale of the product it is supposed to be supporting; full use is made of component advisory services; and the requirements shopping list when making the selection of a data bus to support IMA is largely determined by the size and role of the aircraft.

TRW Aeronautical Systems reported on a two-stage program. HiTEAM 1 was concluded in 1998. The HiTEAM 2 project is currently in its third year. Together with TRW which provides the high temperature electronics, smart actuators and life assessment, Rolls-Royce provides environmental requirements capture and on engine life assessment and Calidus provides passive thermal management, mechanical design and life assessment.

Up to 500 conductors could be used to interface between jet engine sensors, actuators flight control computers and the centralised FADEC. Evolving systems are beginning to apply distributed architecture where smart actuators and sensors replace the centralised control electronics. In such architecture the electronic product is installed inside the actuator or sensor housing. A fully distributed fueldraulic jet engine system would reduce the conductor count from 500 to 8 for duplex control and offer harness weight saving, connector pin reduction, fault detection, a simple FADEC and life cycle cost benefits.

Although there are distinct advantages to distributed control technologies, the one disadvantage is that the electronic product is installed in a harsh environment. Higher temperatures, vibration levels and vastly reduced space envelope contribute to the engineering challenge. The paper summarises the work performed by the HiTEAM 2 consortium led by TRW Aeronautical Systems which will deliver: a 200 C electronic product (with 300 C investigation) together with a smart fuel metering actuator, passive thermal clamp, fire and overheat jacket, Rolls-Royce engine core installation for product life testing, optical position sensor, and a more electric power switch survey.

Boeing Air Traffic Management reported on Required Systems Performance and detailed a tool to characterise airspace and enable transition to improved operations. The evolution towards a CNS/ATM environment is based on the idea that permits maximum flexibility and efficiency of the user while satisfying the high-level airspace requirements for safety and capacity. This extends the current ICAO and RTCA RNP airspace characterisations. In this new CNS/ATM- based system concept, the establishment of system performance, integrity and availability as fundamental, definable, measurable and reliable factors for each system element is essential.

The proposed concept of Required System Performance (RSP) is the means to facilitate the assessment of airspace operational characteristics and the derivation of separation minima. RSP establishes a complete set of performance, integrity, continuity and availability specifications. It has been embraced by the industry standards body RTCA, and was acknowledged by the ICAO Separation Panel. It is used as the basis for new tasks by RTCA to its special committees to develop the technical criteria for RCP (Required Communication Performance) and RMP (Required Monitoring Performance) components of the proposed concept. When finally developed and accepted, RSP will provide an effective and meaningful tool and methodology for a more rapid development and design of airspace operations.

Dy 4 System Inc, Canada posed the question: Will COTS Open Architecture Equipment Find a Place in Civil Avionics? Civil Off-the Shelf (COTS) open architecture equipment has become generally pervasive in the military world of avionics because of its lower initial project development cost, time to market, and the ability to perform planned technology inserts over the lifetime of the equipment. Its consideration and use is a legislative requirement, particularly in North America, but can the same cost and time saving be applied to civil avionics where proof of the safety case is paramount?

COTS in civil avionics has already come a long way. The use of COTS components is now accepted practice and a lot of work has been done by the operating system vendors to make their products acceptable to the certification authorities. The careful adoption of guidelines on targeted product lines by the suppliers of embedded computing assemblies will make the next level of COTS implementation, a practical and Cost-saving alternative to total in-house development. One thing is certain – the cost of bespoke system development and sustainment will make the case for adopting the right sort of COTS increasingly more attractive. The paper demonstrates that this is now becoming a viable and beneficial reality.

Also from TRW Aeronautical Systems was integrating Reliability Improvements into the Design process (Figure 1). Encouraging electronic engineers to consider how their designs operate in the field, and more importantly, lessons that can be learned if they fail, is imperative to successfully achieving reliable deigns. This process may take time and education but will ultimately result in both functional and reliability improvements. Simple analysis techniques are described that may be used by engineers during the early stage of their design. One example is data collection. In-service data is an extremely rich source of information, but it must be managed in a way that can provide the necessary information for successful system intervention, both in the short and long term. This is illustrated in the accompanying figure. With increasing customer focus on reliability requirements and design practices evolving to accommodate changes in component development, the time is right to change the way in which design engineers think about reliability.

Figure 1 In-service data monitoring process

Applications and projects

In the second session the initial paper dealt with HUMS Experience in Military applications and was presented by Smiths Aerospace. Over the past 5 years the adoption of helicopter Health and Usage Monitoring Systems (HUMS) has increasingly expanded from civil offshore helicopters to military helicopters. This transition from the environment in which HUMS technology for helicopters was originally developed has created both new challenges and new opportunities to maximise the benefits of system ownership.

Representative of a typical system is the UK MOD GenHUM system installed on the Chinook helicopter. It has the functions of cockpit voice and flight data recording; rotor track and balance; and transmission health monitoring of vibration, chip warnings, and oil temperature and pressure. From civil experience some of the key lessons leaned are: the importance of effective operational infrastructure; management of false alarms; potential safety benefits from the use of HUMS; and involvement of the helicopter OEM in "backing" HUMS.

Experience with civil HUMS has clearly demonstrated that in terms of both improving safety and providing maintenance benefits, the systems have been effective. In a military environment, the additional challenges in implementing HUMS are primarily data collection on military flight profiles; management of HUMS data for deployed aircraft; and maintenance of expertise in an environment where personnel rotate routinely. Experience to date suggests that there are no fundamental reasons why the military user should not achieve the success of HUMS in the civil offshore sector.

A Demonstration Project on Achieving Information Dominance with Legacy Avionics was given by the Boeing Company. Advances in commercial information technology (broadband, wireless LANs, optical switches and routers, processors) have the potential to enable new tactical architectures characterised by high speed links, high capacity networks and high- performance processors that can transform "data" into usable and timely information readily available to aircrews.

USAF has evolved the concept of Joint Battlespace Infosphere (JBI) as a means to realise information dominance. In the JBI, weapon systems and supporting command and control elements can be considered nodes or IP addresses on a wide area network. However, the cost of replacing legacy sensors, communication links C3 systems, and onboard mission system is prohibitive. For the terminus of the information network the embedded mission avionics system – the cost of deploying a "legacy-free" infrastructure is truly staggering – much akin to the last few kilometres in an information network bringing broadband to the end-user.

Boeing and the Air Force Research Laboratory have defined a demonstration project - IEIST – Insertion of Embedded Infosphere Support Technologies – that explicitly addresses technology for "opening up" resource constrained legacy systems to exploit the evolving JBI. IEIST includes a set of demonstrations that are designed to showcase the situational awareness benefits of these technologies in time critical scenarios with both manned and unmanned platforms.

Aircraft Electronic Technical Logbook and Real-Time Data Management was given by Core-Data Ltd, UK. One of the major challenges facing the aerospace sector over the next few years is the ability to capture, manage and analyse data in a "real-time" mode. Core-Data is developing solutions that will provide currency if data in both an operational and maintenance environment. One such solution is the electronic technical logbook (ETL) which is described in this paper.

This enables all the data currently captured by manual methods (e.g. Techlog data, Delay/ Cancellation reports, Engine Health Monitoring (EHM), to be sent directly and transferred to existing systems. There are principally threadware options available in the implementation of an ETL; palm, handheld and laptop devices, all having a minimum specification. The software on the PED is fully customised to satisfy the individual customer procedural requirements. The data has to be managed effectively and the intelligent aspect of the Core-Data solution provides the knowledge from the data captured.

From ERA Technology came Portable Electronic Devices (PED) and Electromagnetic Compatibility (EMC) Hazards to Aircraft Avionics. Since the early 1960s there have been reports that electromagnetic (EMC) disturbances from items of aircraft passengers carry-on portable electronic devices (PED), such as computers, games and stereos, can affect the performance of aircraft navigation, communication and flight management systems. This paper reviews the history of PED interference to aircraft systems and gives an overview of some of the work which has been undertaken to determine whether or not there is a real problem.

Over the years RTCA and EUROCAE have undertaken a considerable amount of work into the PED interference problem. One of the difficulties is the inability to replicate (under controlled laboratory conditions), the PED aircraft incidents reported by the various airlines. The report also states that "While a small list of suspected incidents of such interference has been generated, the findings indicated that the probability of interference to installed aircraft systems from PEDs singly or in multiples, is low at this time.

The recommendations in the report included: the use of any PED is prohibited in aircraft during any critical phase of flight; and the use of any PED which has the capability to intentionally transmit electromagnetic energy is prohibited in aircraft at all times unless testing has been conducted to ascertain its safe use. From the results of investigations there is a possibility of interference from PEDs affecting aircraft systems via coupling to the aircraft antennas. There are however, a number of factors which in the worst case would require the following conditions to coincide:

^.PED interference signal must be at the same frequency as the aircraft receiver;

^.PED interference signal is at or above the maximum permitted emission limit;

^.PED is located at position of high coupling to the aircraft antenna;

^.Aircraft is receiving a weak wanted signal (i.e. at long range).

System and methodology

TRW Aeronautical System began the third session with Using the REMM methodology which stated the fact that customers demand reliable products and such demands are reflected in the product specification and requirement documents. Indeed contractual obligations are being introduced to ensure that the supplier meets the cost of unreliability. This paper describes the work undertaken under a collaborative project funded by the UK DTI (CARAD) entitled Reliability Enhancement Methodology and Modelling (REMM). The paper shows how REMM can enhance product reliability, illustrating how the methodology can be used by a number of different disciplines. An example is the challenges associated with design for reliability and demonstrates how the REMM tool will encourage designers to consider what might go wrong.

The REMM project was completed in June 2001 and a second phase has commenced for a further 3-year period. REMM 2 is primarily concerned with continuing, expanding and extending the work carried out in the initial phase. This will ensure the significant achievements of REMM are developed to the point where they are capable of being exploited by the partners and extended to other high reliability actions of industry.

Atmospheric Radiation Environment was presented by Matra BAe Dynamics. This noted that trends in flight altitudes, avionics designs and electronic component technology are engendering markedly enhanced susceptibility to atmospheric neutron radiation in modern aircraft. It is possible for individual neutron from this environment to upset or even destroy microcircuits. The radiation intensity increases sharply with altitude and this is the trend to build devices which operate at even lower voltages with ever smaller memory cells and feature sizes tend to exacerbate the intrinsic susceptibility of the devices.

The Radiation Effects Group of Matra BAE Dynamics has been developing a picosecond pulsed laser system for simulating Single Event Effects (SEEs) in microcircuits since 1998 and the paper describes this facility and explains its application to the hardening of avionics against SEEs by filtering out the more susceptible component types from future avionics system design.

Matra BAe Dynamics have established the Single Event Radiation Effects in Electronic Laser (SEREEL) facility, the major ub-systems of which are outlined in the illustration. The laser system has been designed to be capable of achieving large numbers of pulses across a microchip, i.e. under computer control, so as rapidly to generate upset and latchup cross-section curves, in order to provide an efficient screening tool for SEE susceptibility. It is concluded that there is a need for a relatively inexpensive bulk SEE screening facility for Single Effects susceptibility in microcircuits to maintain reliability and safety in future avionics designs.

Bell Technologies Inc, USA gave a paper on the Upscreening of Commercial Temperature Range Integrated Circuits – A Test Lab Perspective. Many manufacturers of integrated circuits are offering fewer industrial and military temperature range parts due to a reduced demand and increased demand for commercial temperature devices. Bell Technologies has gained a unique insight into the problems encountered by companies who require extended temperature range parts. Work has been undertaken with these companies in achieving a solution that assures an on-going supply of parts that are compatible with their requirements.

At Bell Technologies, test lab experience has been considerable over twelve years. In some cases, extended temperature range parts have been available from the manufacturers, but, either because of high pricing or unavailability of the right quantity, some users chose to order commercial temperature parts and have upscreening performed by a testing laboratory. The results of upscreening have shown variations in yield from lot to lot but more recently however, the variations in yield were the result of die revisions that were not characterised for extended temperature performance by the manufacturer.

Replacement of Obsolete ASICs and ICs was by Micro Circuit Engineering, UK and Actel Europe UK and noted that in the semiconductor marketplace, product lifespan continues to be compressed and both standard and ASIC products are being made obsolete at an ever increasing rate. The paper describes the process route available for replacing obsolete ASICs including ASIC redesign and the use of customised Field Programmable Gate Arrays (FPGAs) to avoid an extensive and expensive circuit redesign operation. The factors involved in replacement of the obsolete ASSIC are considered along with the difficulties that may be encountered.

In facing the problem of replacing obsolete digital ASICs, there are two main routes available if components have to be re-produced with the same package footprint and alternative components are not available. They are: Re-design using current ASIC technologies, and using FPGA die in custom packages, the latter being attractive for low volume applications.

Diverse topics

The fourth and last session opened with LROPS – Long Range and Extended Range by Airbus, France. Long range and extended range operations are governed by standards that no longer correspond to the performance and reliability of new products and their future utilisation on new routes. LROPS (Long Range Operations) is the name of the Regulatory Working Group set up by the JAA to review the needs of the operators, the experience and technology related with long range and extended range operations and the proposal of future standards. LROPS should apply to all two, three and four-engined aircraft' and replace the old two-engines-out performance rules as well as ETOPS. Airbus regularly participates in the regulatory work programmes of the JAA, FAA and ICAO.

The challenge for the years ahead is that by 2010 traffic growth in extreme areas will present a serious challenge of operational safety. If the rate of cruise diversions is not significantly improved, six flights may have to be diverted every year to airfields in extreme area (Arctic, Himalaya, etc). At such difficult locations, the situation would not be acceptable. There has to be a new design approach to design out the causes of en-route diversions through advanced technology.