GRP repair
Repair of GRP structure is well understood but the skills are not widespread, take the aircraft to a reputable repair company and you can be assured of a safe repair.
The problems come when un or semi-skilled people work on these aircraft simply becase you can't inspect the repair once it it finnished without NDT kit or taking thie repair apart. It is inspection that is the issue with used GRP aircraft NOT the airworthiness of properly conducted repairs.