a layer of protective film 19 see fig2 and 4 the protective film 19 is centralised and orientated with respect to the crater when applied and defines an oval aperture 20 therein some 5 mm greater in measurement thereacross than the corresponding dimension of the patch see fig3 it will be observed from fig4 that both the protective film 19 and the peel off protective film 2 exhibit alignment markings 21 22 in a longitudinal direction and 23 24 in a transverse direction alignment of these marks during placement of the patch over the crater considerably simplifies the accurate placement of the patch to ensure optimum structural strength of the repair it will be observed that the peel off protective film 2 as shown in fig4 has adhesive ears 25 26 27 28 for secure location of the patch 1 with respect to the structure 11 during cure of the resin adhesive the protective films 2 and 19 are of course peeled off the patch and surface 17 and discarded once the patch is cured in position returning to fig2 and 3 liquid adhesive 15 is evenly spread over the bonding surface 4 of the patch and that part of the surface 17 of the structure.