Never once during those episodes has the United States defaulted on interest payments on the national debt nor has it had to suspend or reduce Social Security payments, although the prospect of both calamities occurring is always used to scare the American public into supporting an unconditional increase in the debt limit fairly quickly after the debt ceiling is reached.
McKinnie committed to paying back the principal, plus interest, which he defaulted on (by missing a scheduled payment) soon after executing the loan documents.