Presidential Airways, the low-fare airline that began operating in the Washington area last month, reported a third-quarter net loss of $3 million (38 cents a share).

The Reston-based company, which uses Washington Dulles International Airport as its hub, attributed the loss to developmental and pre-operating expenses.

"The quarterly results are encouraging and consistent with the developmental expenses expected for an airline in its pre-operational phase," said Collister Johnson Jr., Presidential's senior vice president for finance and administration.

Since Presidential Airways was formed in March, the company has reported a net loss of $3.6 million (73 cents).

Johnson said that the strength of Presidential's cash position should ensure adequate resources to cover start-up expenses and initial operating losses. Presidential raised $19.8 million in equity capital from its initial public offering on Sept. 6., and the company previously had raised $13.7 million in private placements.

Presidential operates more than 20 flights a day from Dulles to five cities -- Boston, Hartford, Conn., Cincinnati, Indianapolis and Miami.

*After winning a judgment against the government of Iran for a canceled contract, Questech Inc. reported net earnings of $415,236 (27 cents a share) for the third quarter. This compared with earnings of $278,552 (18 cents) for the same period in 1984. Revenue rose to $12.53 million from $8.34 million in the 1984 third quarter.

Questech recently was awarded about $1.47 million by the Iran-U.S. claims tribunal at The Hague because of the cancellation of contractual activities with the Imperial Iranian Air Force. The company said that, pending final calculations about litigation costs, $630,000 of the award has been recorded as income in the third quarter.

Questech, which is based in McLean, provides professional, scientific and engineering services in advanced technologies, primarily in the fields of national security, aeronautics, energy and industrial modernization.