In fact, Navy Federal stands out in the 2013 HMDA data as the lender that, by far, made the greatest number of higher priced mortgages in the country last year, twice that of its nearest competitor in the category, the Birmingham, Ala.-based Regions Bank.

According to HMDA data released by the Federal Financial Institutions Examination Council, in terms of loan volume, Navy Federal was among the top 25 mortgage lending institutions in the country.

Townes said the credit union did not think the HMDA data would trigger a fair housing exam because the loans are open to all its members, and because the product's lack of mortgage insurance and down payment meant the credit union required the higher interest rates to cover increased risks. One defense lenders have against suspected discrimination claims is a legitimate business reason for charging a higher rate.

But in March 2013, a letter to federally chartered credit unions from the NCUA indicated that having mortgage numbers that are sharply different from other lenders, so called statistical outliers, is precisely the sort of thing that can trigger a fair lending exam.

“(The) NCUA will review the federal credit union's annual HMDA report,” the agency said in its letter. “If a review of the HMDA report indicates that the federal credit union's lending practices fall outside the normal range for pricing, denials, withdrawals or lending terms when compared to other financial institutions, the federal credit union is considered a HMDA outlier. Federal credit unions that are HMDA outliers and demonstrate the potential for higher fair lending risk are subject to a fair lending exam in accordance with the FFIEC exam procedures.”

In addition to no required downpayment or mortgage insurance, Navy's HomeBuyers Choice loans can carry either fixed or adjustable interest rates. Sellers can also contribute up to 6% of the buyer's closing costs and Navy Federal will make the loans on properties up to $1 million, the credit union's website said.

The nation's largest credit union, headquartered in Vienna, Va., began offering the Homebuyers Choice loans in early 2013 after having offered no-money-down housing loans for some time under different names.