THE Washington Opera is about to launch the most ambitious season of opera in Washington history: 56 performances of eight operas to be performed in 70 days.

Even the pairing of two of the offerings on a double bill does not diminish the scale of the project. Three operas will be performed five times each in the Opera House: Mozart's "Magic Flute," Puccini's "La Boheme" and Verdi's "Macbeth." They will be conducted by Max Rudolf, Cal Stewart Kellogg and John Mauceri.

In the Terrace Theater the company will, in 10 performances starting Saturday night, revive its successful production of Rossini's "Barber of Seville," a great hit there last season, and present 10 performances of Donizetti's "L'Elisir d'Amore," eight of Stravinsky's "The Rake's Progress," and 13 of the double bill of "Monsieur Choufleuri" by Offenbach and the Gilbert and Sullivan "Trial by Jury." And therein lies the rub.

Three of these offerings at the Terrace Theater are comic operas. If it makes sense to bring back the "Barber," it is not good balance to present a Donizetti comedy in the same few weeks. And when, to these two attractions, you add a double bill of a bit of fluff by Offenbach twinned with a Gilbert and Sullivan operetta, you have reduced the total weight of the 41 nights in the Terrace Theater to something very close to an unacceptable lightness.

To pair Offenbach's romp with Gilbert and Sullivan is to bring in an element that -- peace, Savoyards! -- has no business in the Washington Opera scheme of things. Furthermore, the double bill suggests that there is some dearth of superb, exciting, vital works that belong in a gem of a theater like the Terrace, whereas precisely the opposite is true.

Nevertheless, if judgment was lacking in the selection of some of the operas, it was more than evident in the selection of some of the principals: Gian Carlo Menotti, one of the great names in today's opera world, and one of its supreme masters of stagecraft, is the stage director for "Boheme." While he is known for the dramatic intensity with which he stages his own operas, Menotti, who staged Puccini's "Manon Lescaut" for the Metropolitan last season, brings the singular approach of the composer-director to any such assignment.

And Max Rudolf, one of the world's senior conductors, will conduct Mozart's "Magic Flute." He is one of the few men who is as at home in the opera house as on a symphony platform. For years he was one of the top administrative figures at the Metropolitan Opera, from which post he moved to Cincinnati to be music director of its symphony orchestra.

In a direct and welcome return to the policies that guided the Opera Society of Washington throughout its early years, the company is engaging almost all (though wisely not all) young American singers.

It is a daring move on the local company's part to present Verdi's first great Shakespearean drama, since many in the audience will have seen the unforgettable production of this work on the same stage five years ago when La Scala brought its magnificent Zeffirelli-produced "Macbeth" with Shirley Verrett and Piero Cappuccilli under the baton of Claudio Abbado. That production, in turn, had been preceded by an earlier Opera Society of Washington presentation.

Stravinsky's sole full-length opera, "The Rake's Progress," is enjoying some revivals this year, thanks to the centennial of its composer's birth. But again there is a question about putting it up in the Terrace Theater when it has already enjoyed a production by the Opera Society of Washington on the Opera House stage. Stravinsky certainly never urged that it be confined to smaller houses. On the contrary, he conducted its world premiere in Venice's exquisite Fenice Theater, and it has been heard from the stage of the Metropolitan under Fritz Reiner's baton, and in a brilliant production, much praised by the composer, by the Hamburg Opera.

It is entirely possible that the "Rake" will appear in a welcome new light in the intimate reaches of the Terrace Theater. For one thing, its text may come across more distinctly there. However, one must remember that even when the libretto, the work of W.H. Auden and Chester Kallman, is clearly sung, its meanings, alas, are often cloudy.