Modern airliners utilise substantially more composite materials than in the past. For example, composites in primary and secondary structural parts of the Boeing 787 account for approximately 50% of the total airframe weight, as opposed to approximately 10% for the older generation Boeing 777.

The maintenance programmes for aircraft composite structures are still evolving to become more effective, to detect reliably potential defects, and more efficient, to facilitate productivity within the maintenance, repair and overhaul (MRO) service providers.

In turn, MRO personnel are expected to understand the safety implications arising from poor handling, damage reporting and repair practices on composite structures. Any limitations in knowledge around these safety-related matters, which might originate from limited awareness and/or insufficient training, can have a significant impact on the effectiveness of maintenance tasks.

Moreover, the relatively short in-service experience with airframe composite materials and non-standardised repair techniques have been identified as safety concerns. The maintenance workforce is predominantly accustomed to inspecting and repairing metallic aircraft structures, having less appreciation on the differences between composites and metals, especially in relation to non-visible or barely visible impact damage.

The paper ’Handling, Inspection and Repair of Aircraft Composites: A Pilot Study on the Awareness of Maintenance Personnel’ explored the level of awareness and understanding of aircraft MRO personnel around handling, inspection and repair of aircraft composite structures, as well as on damage reporting in the case of non-visible or barely visible impact damage. This research study from the University of Limerick sought to unveil issues related with the technical/engineering judgement capacity of the maintenance personnel working with composites and to explore the need for specialised education and training.

A questionnaire-based survey was conducted within a single aircraft MRO facility, with 40 licenced aircraft maintenance staff participating in this study. Despite the limited size of the study’s participants, this research revealed some issues with an importance for safety and productivity:

• The source of impact during in-hangar and outside hangar maintenance, as well as the impacted areas on the aircraft can differ. In the hangar, wing/flap area and the aircraft lower surface are the most heavily impacted according to the responses of the participants. Situational awareness is considered the most profound mitigator against impact damage.
• The high percentage of participants that would refer to their engineering manager for instructions on how to handle damage on composites is highlighted (approximately 70%–90%). This may be attributed to the lack of specialised documentation, or the less prescriptive format of the existing instructions contained in aircraft manuals. However, these results cannot be generalised to wider population, due to limitations associated with the sample size.
• The majority of respondents (approximately 60%) did not report the anticipated value range of the load carrying capacity lost due to impact damage on typical composite structures used in aircraft. This is indicative of a lack of specialised knowledge around these topics.
• Facilities/resources are highlighted as the most important aspect in the transition to fleets of more-composite aircraft, followed by training and situational awareness. The potential lack of special tools, apparatus and methods to inspect and maintain aircraft composites appears to be a concern among the aviation practitioners surveyed.
• While most of the participants responded that are not involved in the repair of composites, the results indicate that there is a general knowledge on the typical repairs and inspection techniques. However, almost all respondents agree on the need for specialised knowledge and training for the handling, repair and inspection of composites. An inclination towards training, as opposed to knowledge has also been indicated, though, again, this cannot be generalised to a broader population.

This study has also identified the need for extant work, which is currently planned by researchers at the University of Limerick.

’Handling, Inspection and Repair of Aircraft Composites: A Pilot Study on the Awareness of Maintenance Personnel’ by C. M. Jong, A. J. Comer, A. V. Chatzi, and K. I. Kourousis. This open access paper appears in Volume 128 – Issue 1320 of The Aeronautical Journal.

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