Airfoil with body and cover panel

An airfoil comprising:

• a metal body having holes, the holes having undercuts;
• a cover panel carried on the metal body;
• and
• push fasteners extending through the cover panel and locking the cover panel on the metal body, each of the push fasteners including flexible barbs, wherein upon insertion of the fasteners into the holes the flexible barbs compress to fit into the holes and then decompress upon reaching the undercuts such that the flexible barbs engage the undercuts and prevent retraction of the fasteners from the holes to thereby lock the panel on the metal body,
• wherein the push fasteners include heads that are embedded in recesses in the cover panel, and further comprising a film disposed on the cover panel, the film extending across the recesses such that the film encloses the recesses.