	moody s may downgrade piedmont aviation pie moody s investors service inc said it may downgrade mln dlrs of debt of piedmont aviation inc because of the airline s agreement to be uired by usair group inc u the rating agency said its review would focus on the effect of the uisition 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 preferred stock and prime commercial paper reuter 
