The Secretary is authorized to make expenditures to correct, or to reimburse the owner for the correction of, structural or other major defects which so seriously affect use and livability as to create a serious danger to the life or safety of inhabitants of any one, two, three, or four family dwelling which is covered by a mortgage insured under section
1715z of this title or which is located in an older, declining urban area and is covered by a mortgage insured under section
1709 or
1715l of this title on or after August 1, 1968, but prior to January 1, 1973, and which is more than one year old on the date of the issuance of the insurance commitment, if