Airport Limo Inc. has applied for permission to raise its fare for bus service between Washington and Dulles International Airport an average of nearly 11 percent, pushing the present $7 cost for a trip to or from downtown up to $7.75.

In its application to the Washington Metropolitan Area Transit Commission, the firm said it would lose $8,263 in the coming year without a fare increase. With the increase, it forecast a profit of $175,810. The commission's general counsel, Gregory Paul Barth, said he expects the commission to act on the application this month without holding a public hearing.

Airport Limo, which on April 1, 1980, took over service to both National and Dulles International airports previously operated by another carrier, also requested raises in fares between the city and National and between the two airports.

Under its proposal, the fare between National and Dulles would be $7.75, the same as the fare between Dulles and two downtown terminals, the Capital Hilton and Washington Hilton hotels. The fare from Dulles to the Sheraton Washington Hotel, now $7.25, would rise to $8. The fare from National to either of the Hilton hotels would rise from $3.25 to $3.50, and to the Sheraton it would go from $3.75 to $4.