Cold spray repair extends life of aircraft wing skins

Background

Aircraft operate in demanding environments that can challenge the integrity of wing skins, particularly around rivet joints. Extended aircraft groundings, such as during Covid-19, highlighted the need for durable repair methods that maintain structural performance and keep aircraft in service for longer.

Conventional repair methods involve epoxy fillers, which patch corroded areas but are brittle and prone to further damage, and doubler plates, which are extra metal layers riveted over weakened sections. While these approaches can extend service life, they also add weight, reduce fuel efficiency and eventually limit further repair options.

For operators and maintenance teams, this presented an opportunity to explore advanced repair methods that would reduce downtime, improve durability and support more sustainable maintenance practices.

Challenge

Traditional approaches can mean repeated interventions, added costs and increased material use. The industry was therefore looking for a more durable and efficient solution that would:

 

• offer stronger corrosion resistance than epoxy filler
• avoid the added weight of doubler plates,
• extend component life, and
• integrate seamlessly with standard maintenance, repair, and overhaul (MRO) processes

What did NMIS do?

Working in collaboration with global aerospace companies as part of the ReMake Programme, engineers from the National Manufacturing Institute Scotland (NMIS) developed a novel cold spray repair process, a large-scale additive manufacturing technique, designed for direct on-wing application.

Cold spray was identified as the most suitable additive repair technique due to its low operating temperature. Unlike other deposition methods, it can be applied inside hangars without major disassembly, making it practical for maintenance, repair and overhaul (MRO) operations.

A range of materials were assessed for the repair process, including AA7075 (a high-strength aerospace-grade aluminium alloy) and commercially pure aluminium. These materials underwent mechanical and environmental testing to compare their performance with traditional epoxy-based repairs. To enhance durability, particularly under the low-pressure cold spray conditions, ceramic-reinforced variants were also trialled. The use of lower pressures was key to enabling more portable use of the equipment in the hangar.

A wing skin repair process was produced, showing the full workflow – corrosion removal, cold spray application, blending, and surface restoration.

The process was carefully refined to ensure strong adhesion, minimise defects, and accurately rebuild damaged areas, with full traceability recorded from the start to support future integration with digital product passports.