BiDebA

BiDebA

GMI cooperates with EU Partners in the field of

Biobased Adhesives to create

Debondable Composite Patches for aeronautical applications

A Constellation of distinguished EU entities

In its continuous effort for Innovation and Excellence, GMI Aero participates in the Biobased Debondable Adhesives - BiDebA project, co-funded by Interreg NWE. Together with four more prestigious entities from a total of three EU countries – Flanders Make (BE), Avans University of Applied Sciences (NL), TU Delft | University of Technology (NL) and ACRATS (NL), GMI Aero will be actively working towards the development of Biobased Debondable Adhesives and associated methodology, equipment and toolings, for application in the Transportation sector.

Aiming at Circular Economy

Aligning with the circular economy's waste hierarchy principles, extending the lifespan of composites through repair and reuse is crucial. The major challenge lies in the inextricable bonding of composite materials through adhesives. Conventional adhesives exhibit a two-fold challenge: 

1) they are primarily produced from fossil fuels and are therefore non-renewable.

2) Once applied, they hinder detachment and hence further repair, reuse, and recycling. 

Addressing this challenge is particularly desirable in the North-West Europe region, which has the largest composite and adhesive market share in Europe. BiDebA aims to develop one solution for circular composite repair by engineering bio-based adhesives, derived from renewable resources, to facilitate effortless detachment of the parts on command.

Bio-based adhesive formulations

BiDebA novel approach draws inspiration from historical materials and integrates recent developed bio-based adhesive formulations into existing pilot-scale debonding and composite repair setups from the project’s partners. Finally, this will result in one pilot scale demonstrator. Through transnational pilot-scale demonstrations on a representative use case, BiDebA will showcase the applicability of this novel approach for non-structural composite parts. The project focuses on the transportation sector, the largest consumer of composites, and more specifically companies involved in composite repair. Via these demonstrations in the region that represents the largest market share, BiDebA aims to convince companies to adopt these technologies in their products and processes, and hence to advance the repair of composite materials.

Composite Repair in Aeronautics

The goal of any commercial aircraft maintenance and repair crew is the fastest safe return of the aircraft to service — especially in view of the fact that the cost in lost revenue of an unscheduled AOG (aircraft on the ground) is, on average, $100,000 per day. No wonder, then, that in the run-up to the launches of the Airbus A380 and Boeing 787, much has been made of airline and maintenance and repair organization (MRO) concern about how aircraft composites would be repaired. Considering that the average permanent composite repair, as permitted in Structural Repair Manuals (SRMs), takes roughly 15 hours, according to SAE's Commercial Airline Composite Repair Committee (CACRC), in-situ composite repairs performed at the flight line can cause flight delays and cancellations. It's a dilemma made more challenging by fast gate turnarounds — between 30 and 60 minutes for domestic flights — and an overwhelming lack of line mechanics with specialized composites training. But aircraft OEMs, airlines and MROs are crafting strategies to minimize ground time, simplify repair regimes and make composite materials and processes accessible to technicians who are more accustomed to working with metals.

The most disruptive repair situation, in terms of downtime, is the unscheduled repair. Impact damage, hail damage, and moisture ingress/intrusion are the most common types of damage to composite structures that cause an aircraft to be taken abruptly out of service. Most repair materials have a finite shelf life, and MROs perform a balancing act to keep adequate repair materials on hand without having extremely high material waste. Each operator must forecast material use well in advance because "currently, lead times of more than 20 weeks are not uncommon. Operators with multiple fleet types often face the challenge of stocking multiple types of the same material, such as three different types of 350°F/177°C carbon fabric prepreg."

The concept of Quick Composite patch Repair (QCR) enabled through BiDeBa

Many repairs to composite structures carried out by aircraft line maintenance technicians are low-temperature (room temperature to 150°F/66°C) wet layups, which are typically temporary or time-limited repairs. These technicians, who are typically generalists with minimal training in composites repair, must diagnose and correct both minor and major aircraft damage at the gate. A room-temperature wet layup repair requires no disassembly and no external heat sources, such as hot-bonding equipment, which would require more extensive training to pro operate and can be hazardous when used on a fueled aircraft. Another consideration that aircraft manufacturers are dealing with is the issues involving low energy impacts, such as a tool drop. This type of impact may cause the structure to be slightly damaged within the laminate, while no damage is visible on the exterior. If the damage is not visible then it may not be detected, and in turn not repaired, until a heavy check is performed – one that is designed to detect this level of damage.