24 CFR § 241.555 - Security instrument and lien.
(a) The security instrument shall cover the entire property included in the project, shall be a lien on the real property of the project under the laws of the jurisdiction in which the project is located, and may be junior to such prior liens or mortgage indebtedness as the Commissioner may approve. The security instrument shall contain a provision that a default under the first mortgage is a default under the supplementary loan security instrument.
(b) For bond-financed projects where the bond resolution contains a provision prohibiting the creation of additional liens, the Commissioner may accept at his/her option:
(1) A first lien on another property whose fair market value as determined by the Commissioner equals or exceeds the amount of the loan insured under this part;
(2) A Collateral Account in an amount not less than the amount of the loan insured under this part funded with cash or negotiable bonds or securities backed by the full faith and credit of the United States Government; or
(3) Other security acceptable to the Commissioner.