A new technique that mimics the natural healing process could enable damaged aircraft to automatically mend themselves, even during flight.

The technique, developed by aerospace engineers at Bristol University, is based on the bruising and bleeding/healing process seen in humans, and has the potential to be used wherever fibre-reinforced polymer (FRP) composites are used.

The technique involves filling the hollow glass fibres contained in FRP composites with resin or hardener. When the fibres break, perhaps due to a tiny hole or crack appearing in an aircraft, the resin and hardener ‘bleeds’ out, enabling the composite to recover up to 80 – 90 per cent of its original strength – allowing the plane to function at its normal operational load.

By mixing dye into the resin, any ‘self-mends’ would show as coloured patches that could be easily pinpointed during subsequent ground inspections, and a full repair carried out if necessary.

Project leader, Dr Ian Bond, explained: “This approach can deal with small-scale damage that’s not obvious to the naked eye but which might lead to serious failures in structural integrity if it escapes attention.

“It’s intended to complement rather than replace conventional inspection and maintenance routines, which can readily pick up larger-scale damage, caused by a bird strike, for example.”

It is hoped that the Engineering and physical Sciences Research Council funded project, will be commercially available with in the next four years.