MOODY'S MAY DOWNGRADE PIEDMONT AVIATION <PIE> Moody's Investors Service Inc said it may downgrade 120 mln dlrs of debt of Piedmont Aviation Inc because of the airline's agreement to be acquired by USAir Group Inc <U>. The rating agency said its review would focus on the effect of the acquisition on Piedmont's financial leverage and its debt-service requirements. Moody's said it is also examining the potential use of the airline's borrowing capacity to finance the merger. Piedmont currently carries Baa-2 preferred stock and Prime-2 commercial paper.