On 25 October 2013, the crew of a Bombardier CRJ 900 made an unstable visual daytime approach to San Sebastian which culminated in a hard landing of sufficient severity to trigger an inspection in accordance with the AMM. The inspection did not occur and the aircraft made a further revenue flight before the hard landing was reported and substantial landing gear damage was discovered. The unstable approach at a Category 'C' airport was found to have been flown by the First Officer contrary to applicable regulatory requirements.