Once a lender extends a loan that is guaranteed or insured under the Program, BIA has no responsibility for decisions concerning it, except for:

(a) Any approvals required under this part;

(b) Any decisions reserved to BIA under conditions of BIA's guaranty certificate or insurance coverage; and

(c) Decisions concerning a loan that the lender has assigned to BIA or to which BIA is subrogated by virtue of paying a claim based on a guaranty certificate or insurance coverage.