Presidential Airways, a new low-cost airline that uses Washington-Dulles International Airport as its hub, reported continuing red ink in the last three months of its first year of operation.

The carrier said it lost $5.3 million (54 cents a share) in the three months ended Dec. 31, on operating revenue of $7.0 million. The company also reported a net loss of $8.9 million ($1.48) since its incorporation last March 5.

"Revenues were impacted slightly by price discounting in effect throughout a substantial part of the fourth quarter due to competitive response generated by Presidential's entry into the marketplace," said Collister Johnson Jr., senior vice president for finance and administration.

Johnson said, however, that termination of discounting by Presidential and its competitors in February is expected to produce higher yields.

*Star Technologies Inc., a manufacturer of high-speed scientific computers that is undergoing a significant restructuring, reported dramatically increased losses for the quarter that ended Dec. 31.

The company, which is based in Sterling, Va., said it lost $5.7 million (43 cents a share), more than four times the $1.3 million (11 cents) it lost in the same period in 1984.

The company said its quarterly losses included $1.5 million in one-time costs associated with previously initiated restructuring actions, as well as inventory adjustments during the quarter. The company said its overall employment has been reduced 50 percent since mid-1985 as a result of the restructuring.