Impact on composite structures shows a different damage behaviour compared to metal structures. Due to the current short operational life time of composite aircraft the risks of impact damages on composite structures are unknown. This paper proposes a new method for quantitative risk analysis of low velocity impact damages on composite aircraft structures by combining a conventional risk analysis with the probability of detection of the damages. Real damage data of metal structures is used to estimate impactors and to predict damages on composite structures by means of an aircraft impact damage model. To create a large set of impact events and to conduct a more accurate analysis impactor data estimated from the real metal damage data is augmented. Three fuselage sections with a significant difference in amount of damages have been selected to compare the different risk results. The outcome of a conventional risk analysis and the outcome of the probability of detection of damages show that the section with the highest amount of damages results into the highest risk. However, the proposed method by combining the probability of detection of the damages with a conventional risk analysis shows different and more revealing results. The fuselage section with nearly 50% less damages compared to the section with the highest damages appears to be the highest risk section but the difference with the other fuselage sections is small. The proposed risk analysis method intends to be a useful tool for aircraft maintenance organisations for a different approach of assessing the risks of impact damages on composite structures.

Some aircraft damages require immediate attention. Typically, there are several alternative actions, resulting in varying outcomes. Application of MCDM was investigated to quickly choose the best scenario, as this is not always immediately apparent. In doing so, this research contributes to the state-of-the-art by a) considering alternative evaluation for multiple simultaneous operational occurrences and b) performing a comparative analysis of several MCDM methods in terms of applicability, suitability and robustness. WSM, TOPSIS and VIKOR have been identified as potentially appropriate. Using the criteria survivability, time and cost, different scenarios have been evaluated. It resulted that for single occurrences the outcome only varies for very extreme weight settings. In a multiple damage occurrences scenario, i.e. several aircraft competing for limited resources, differences have been found. While TOPSIS and VIKOR generate similar recommendations, WSM yields different results. Furthermore, it was found that VIKOR is not suited for the used heuristic approach, as it results in an ambiguous performance score of several solutions relative to each other. Its sensitivity makes its use in an operational environment questionable, as small changes easily lead to a different recommendation. Looking at the frequent use of a DSS in an operational environment as opposed to a strategic one, WSM is the best choice. This is due to its ease of implementation, its robustness and its simplicity.