Research projects - Large aeroplanes

In the view of changing aircraft operation envelope due to increasing performance of modern aircraft and having in mind a potential climate change and consequent changing environmental operating conditions the objective of this research project aimed at studying of the variety of fundamental scientific issues related to the microphysical properties and structure of deep convective cloud systems over land and over the warm tropical ocean, and the engineering and scientific issues related to characteristics of these convective clouds.

Secondly the project aimed at validating of the environment envelope in the proposed amendments of certification rules or compliance in mixed phase and glaciated icing conditions including the identification of areas which require a further amendment / extension of the envelope and the definition of necessary actions for a more detailed flight test characterisation with in particular determination of the composition of cloud masses at high altitude with the appropriate precision.

Contributing on one hand to the improvement of aviation safety, the results also allow to be used as a unique resource for further fundamental research, for new industrial developments of engines, air data systems, and detection and/or awareness technologies to be fitted on aircraft and able to alert the flight crew when entering particular icing conditions.

The objective of the study was to provide EASA with data and analyses that would assist EASA in writing and publishing guidance material on the subject of the use of multi-core processors in safety-critical airborne systems. These systems would be of Development Assurance Levels (DAL) A, B or C in compliance with CS 25.1309 (a) and (b), ED-79A / ARP4574A, ED-12B / DO-178B, ED-80 / DO-254 and EASA Certification Memoranda 001 and 002 for Airborne Electronic Hardware (AEH) and Software.

The study identified the types of multi-core processors being produced now and in the near future by some of the major processor manufacturers. It described the internal architectures of those processors and the types of software architecture that can be implemented for the processors.

The study provided details of some of the features of multi-core processors that EASA had identified as having potentially adverse effects. It suggested some criteria related to those processor features that could be used in deciding whether or not a processor was suitable for use in airborne safety-critical applications.

The study provided a set of recommendations regarding processor selection and the handling of those multi-core processor features that could be problematical for their use in safety-critical systems. It also reviewed the existing EASA AEH Certification Memorandum and made some suggestions on how the section on COTS processors might be applied to multi-core processors.

The objective of this study was to survey the different tools currently in use for the development of programmable Airborne Electronic Hardware which are or will be used in safety critical applications, assess their functionalities and configurability options, and derive detailed recommendations and guidelines for their effective and safe use in the development of programmable devices and, in particular, concerning their configuration options. By this, the primary intent was to assess the best-practices and known issues in using a set of commercial tools from a survey of past experiences and consultation of designers and tool editors.

The study does encompass the typical tasks supported by tools including design (conceptual and detailed design), validation and verification processes and this for development assurance levels A, B and C defined by EUROCAE ED-80. The current set of commercial tools used for the development of civil aviation applications were considered, involving a consultation of aircraft and equipment manufacturers in support of the tool selection.

The objective of this study was to compile the results of studies and work done, as well as any instructions and directives issued by civil aviation authorities to date, concerning the principles and guidelines relative to the design of checklists and working methods in the cockpit so as to allow European operators and manufacturers and National Aviation Authorities to have clear references on the state of the art in the design and application of checklists.

The study, supported by the European Human Factors Advisory Group (EHFAG), takes into account normal, abnormal and emergency check lists with priority to commercial air transport, but attention is also given to rotorcraft (commercial operation) and business aviation and reference material such as UK CAA CAP 676.

It is commonly recognised that significant damages, e.g. delamination, blind-side fibre damage (damage modes which can further weaken the existing undamaged critical failure modes), may be difficult to detect visually in composite structures, e.g. NVD (Non-Visible Damage), BVID (Barely Visible Damage).

A particular concern is low velocity high-energy blunt impact, e.g. by ground vehicle impact. This problem may worsen due to ground vehicle shock absorbers (introduced to reduce damage to metallic structure) which have the potential to make damage detection more difficult.

The objective of the study is to improve the understanding of impact damages to composite structure (principal structure element) and their detection with a particular focus on high-energy blunt impact (within the bounds of CS-25 allowable damage limits (ADL) dimensions) occurring during ground operations.

The recent rapid increases in the use of composite materials in Principal Structural Elements (PSE), particularly in CS-25 designs, has driven a generic expectation that the use of such materials should not reduce the level of safety provided by existing more conventional materials. The properties of metallic and composite structures can nevertheless differ significantly, e.g. composite materials are heterogeneous, so typically exhibit significantly more anisotropic behaviour (including more failure modes), than a metallic structure.

The LIBCOS study "Impact Behaviour of Loaded Composite Structure" assesses the comparative behaviour of composite and metallic structures concerning damage tolerance to high-velocity foreign object impacts (e.g. bird strike, hail, tyre rubber and metal fragments) and under various flight loads (tension and compression).

The joint EUROCAE ED-12B / RTCA DO-178B standard, Software considerations in airborne systems and equipment certification, is recognised as an acceptable mean of compliance for the certification of safety critical software on-board large aircraft (EASA CS-25). However, this standard does not fully encompass several new technologies and methods that have been developed since its publication and are currently used by aircraft and equipment manufacturers.

The SOMCA study assesses the application of Model-based software development techniques to perform structural coverage analysis at model level, with a focus on the detection and characterisation of unintended functions. The assessment covers as well the pre-requisites, the recommended acceptance criteria and practices to use model coverage analysis in relation to certification activities.

The EASA requirements for supplemental oxygen in large aircraft cabin (CS 25.1443) correspond to constant flow oxygen systems and test methodologies available at the inception of the rule forty years ago.

The aim of this study was to develop both equivalent requirements and associated Acceptable Means of Compliance (AMC) using the measurement of arterial oxygen saturation (SaO2) of hemoglobin as a more efficient way to assess the performance of oxygen systems to be installed in aircraft. Additionally, the revised requirement will be independent of the technology used.

This study has provided a survey of hail physical characteristics and hail size distribution properties. It also attempts to present the hail threat based to some extent upon correlation between global meteorological models and limited existing data. The extreme values provide worst case estimates for hail density and relative frequency as a function of size. The probability tables can be used as an estimate of the worst case probabilities of intercepting hail of different sizes for use in designing aircraft structures. The tables also indicate that multiple hits from smaller hailstones are potentially a problem that aircraft designers need to consider.

A review has been produced of the use of composites in aircraft production, the existing test standards that are relevant for hail threat, the mechanical characteristics of ice and the damage caused to test composite structures. This has been carried out for a range of relevant hail sizes and impact velocities.

This report is intended to provide input for the development of a harmonised hail threat and simulation definition.

The study focuses on understanding the following: the composite damage metrics and the variables that influence damage detection e.g. colour, finish, lighting, cleanliness, angle at which the inspection is conducted relative to the surface. This requires consideration of the reliability of detection in relation to these variables.

It may be necessary to consider metrics, other than the classic dent or assumed delamination in a no-growth test, and to exploit all variables to maximise the chances of finding damage. Reliable damage detection needs to be achieved without generating nuisance findings.

There is a trend in the aviation industry to adopt so-called System-on-Chip (SoC) technology at a high scale integration level also in airborne critical applications. The SoC are mostly available as Commercial of-the-shelf (COTS) devices. Due to the high production rate and production volume they cost significantly less than those developed intentionally for aviation applications.

The subject of the study is to investigate the safety implications of the use of System- On-Chip (SoC) technology in airborne critical applications which is implemented and integrated using Commercial Of-the-Shelf (COTS) cores and devices that were not designed for critical application or that were not designed following ED-80.

The study focused on an assessment of the actual SoC and core supplier's best practices with respect to design assurance level and ED-80 objectives, and the foreseen evolutions of these practices. A survey was performed concerning data related to SoC cores available on the market with the intent to provide details on development assurance data (design documentation, verification, errata management) which would allow a safe use of these SoC in airborne systems.