Repair, Don't Replace: Vitrimer Tapes for Toroidal Propellers That Can Be Fixed On Site

What if a damaged composite propeller could be repaired quickly, safely, and sustainably on site instead of being replaced?

In its continuous effort for Innovation and Excellence, GMI AERO participates in the TorPropel EU R&D project, together with a constellation of distinguished EU entities, towards increasing repairability of composite materials. Also aligning with the circular economy's waste hierarchy principles, extending the lifespan of composites through repair and reuse is crucial.

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. To this end, an entire range of bonded composite repair and associated methodologies has been developed and made available to the market since almost 40 years, while innovative solutions are continuously adopted to face contemporary aircaft challenges, such as repair of A350 & B787 all-composite aircraft.

The advancement proposed by TorPropel includes the development of novel vitrimer tapes based on the 3R system, to be used for the rapid production of toroidal propellers that will be easy to repair and intrinsically recyclable. Resins based on vitrimer chemistry are examined, combining main advantages of current thermoset resins (processing conditions/temperature, mechanical properties) and thermoplastic resin (recycling, re-processability, repairability, welding). 

Standardized repair methodologies will be developed by GMI AERO based on existing protocols and vitrimer resins to ensure efficient maintenance and repair of toroidal propellers. State-of-the-art composite repair equipment such as ANITA hot bonders and OLGA positive pressure application device will be adapted for the performance of composite repairs to toroidal propellers, compliant to aeronautical standards.

Structural analysis of the toroidal propeller demonstrators will be conducted, following experimental testing, to evaluate their integrity with the use of advanced diagnostic techniques, such as U/S inspection and thermography. The objective is to detect any internal or surface damage performed during testing, under simulated operational conditions. The feasibility and effectiveness of repair methodology and associated equipment for composite propellers will be also validated, targeting to the restoration of the propellers to their original condition, through the advanced repair properties of the vitrimer based tapes.