(a) A loan to be eligible for insurance shall be on real estate held:

(1) In fee simple; or

(2) On the interest of the lessee under a lease for not less than ninety-nine years which is renewable; or

(3) Under a lease having a period of not less than “twenty-five” years to run from the date the loan is executed.

(b) The property constituting security for the loan transaction must be held by an eligible borrower as herein defined and must at the time the loan is insured be free and clear of all liens other than those specifically approved by the Commissioner.