Research projects - Large aeroplanes

Detailed description:

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).

Detailed description:

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.

Detailed description:

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.

Detailed description:

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.

Detailed description:

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.

Detailed description:

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.