Federal Government job disability

My husband is 100% T&P retired AF. He also works for the federal government. About 2 months ago he got an injury ( not work related) and has been out of work. He said that there is no Short Term Disability available to him and that he has to file for Social security disability. This can take a very long time if he were to get approved, meanwhile he isn't earning a pay check from his job. They have him on FMLA His boss is of no help at all and there isn't really any HR department that he can contact. I just can't believe that there isn't any type of disability available to someone who has a medical accident and can't work. Any advise? Thanks