THE AMERICAN Film Institute offers an impressive line-up this week beginning with two showings of the complete 212-minute version of William Wyler's Ben Hur on Friday at 8:15 and Saturday at 8:45. The gargantuan 1959 production netted MGM 11 Academy Awards, the most ever for a single film. More often than not, the "Ben Hur" you see on TV is a shorter, 165-minute version.

Coincidentally, Best Actor Charlton Heston will be at the Kennedy Center during both screenings but will not be able to introduce the film. He's directing and starring in "The Caine Mutiny Court Martial," which opened Thursday at the Eisenhower Theater. Heston is probably best remembered for his part in the action-packed chariot race, which was choreographed by rodeo-champion-turned-stuntman Yakima Canutt. Canutt, who won a special Oscar in 1966 for helping create the stuntman profession, died last Saturday in Hollywood at the age of 89.

On Saturday, the AFI begins another episode in the year-long celebration of the 50th anniversary of the Directors Guild of America. During the next four weeks, the theater will feature films made by producer, writer and director Joseph L. Mankiewicz, starting with his 1942 production Woman of the Year. George Stevens directed the brilliant social comedy, which stars Spencer Tracy, Katharine Hepburn and William Bendix. The series continues on Tuesday at 6:30 with another of Mankiewicz' productions, The Philadelphia Story, which was directed by George Cukor. It repeats the following day at 6:30.

To help celebrate the diamond anniversary of naval aviation, the AFI has added still more action flicks to its menu. On Monday at 8:45, see Warner Brothers' Wings of the Navy. The 1939 film, shot at the Navy's flight school in Pensacola, Florida, stars Olivia de Havilland, George Brent and John Payne. The 89-minute black-and-white feature is double billed with The Fleet That Came to Stay, 20 minutes of combat footage shot by Marine, Coast Guard and Navy cameramen, which shows Kamikaze attacks against American ships off Okinawa in 1945.

Then, on Thursday at 8:30, Frank Capra's 1931 Dirigible stars Fay Wray, Jack Holt and Ralph Graves. The film was shot at the Navy's dirigible base in Lakehurst, New Jersey, the same base where the Hindenburg exploded in 1937, killing 36 aboard and virtually putting an end to dirigible travel. The film is double-billed with Devil Dogs of the Air, starring James Cagney, Pat O'Brien and Margaret Lindsay.

But possibly the most emotionally packed AFI evening of the week comes Tuesday at 8:45 when independent filmmaker Manfred Kirchheimer introduces his award-winning documentary We Were So Beloved . . ., the story of more than 20,000 German Jews who settled in the Washington Heights section of New York City during Hitler's reign. German-born Kirchheimer, whose parents fled Germany in 1936 when he was five, is the film's producer, director, writer, narrator, cameraman and editor. He has gleaned film footage from several major collections and interviewed countless German transplants, including his family members. The film runs 145 minutes. Call the AFI box office at 785-4601; or the recording at 785-4600.

Don't let the crowds keep you from seeing a really good thing, the "Hollywood: Legend and Reality" exhibit at the Museum of American History. The seven-section display covers 70 years of Hollywood with more than 450 photographs, posters, costumes and such props as the tiny piano last played in Rick's Cafe from Casablanca, Citizen Kane's "Rosebud" sled (loaned by owner Steven Spielberg), and the rotating dummy head from "The Exorcist." The Smithsonian has resorted to passing out free admission tickets to weekend visitors in order to maintain an even traffic flow, but you shouldn't have any difficulties seeing the exhibit during the week. The museum is open every day from 10 to 5:30; the exhibit runs through June 15. Call 357-2700.

The Smithsonian Resident Associate Program's "Gems of Hollywood Genres" series, which is running in conjunction with "Legend and Reality," screens The Women in the Window on Wednesday at 7:30 in American History's Carmichael Auditorium. The 99-minute, black-and-white murder thriller stars Edward G. Robinson and Joan Bennett. Cost is $5 for RAP members; $6.50 nonmembers. Call 357-3030.

SHORT TAKES -- You won't have to rely on your memory to conjure up scenes of the famous New York World's Fair of 1939. The World of Tomorrow will do it all for you. Filmmakers Tom Johnson and Lance Bird use home movies, newsreels and photographs along with narration by Jason Robards in their 83-minute story of the fair that promised visitors a window into the future of technology. It screens free at noon on Friday at the National Archives Theater, Pennsylvania Avenue at Eighth Street NW. Call 523-3347.

The Brazilian-made The Hour of the Star gets its American premiere on Friday at the Brazilian-American Cultural Institute. Based on the book of the same name, Suzana Amaral's 96-minute movie has captured more than a dozen awards at international film festivals. The film is in Portuguese with English subtitles. A $5 donation is requested for the 8 p.m. screening at the 130-seat Cultural Institute theater, 4103 Connecticut Avenue NW. Call 362-8334.

The Baltimore Film Forum reports a record 25 percent increase in ticket sales to its month-long International Film Festival, which ended several weeks ago. More than 5,000 moviegoers in all were attracted to the festival, which included premieres for such movies as 28 Up and Sweet Liberty.

On Friday at 8 the Forum concludes its Italian-made picture series with Lina Wertmuller's unforgettable Seven Beauties. The 1976 film stars Giancarlo Giannini. On Thursday, "New French Cinema" begins a three-day run with two Baltimore premieres for the price of one: L'Acrobate (The Acrobat) and Le Voyage A Paimpol (Journey to Paimpol). They screen at 7:30 and 9:15, respectively. For a complete schedule, call 301/685-4170. All films screen at the Baltimore Museum of Art, 516 North Charles Street. Call 301/685-4170.

On Saturday afternoon at 2:30, local film critic Joel Siegel will introduce Herbert Ross' 1981 Pennies From Heaven, starring comedian Steve Martin, Bernadette Peters, Christopher Walken and Jessica Harper. It's all part of the ongoing free series "Through the Frame: Film Encounters the Painterly Image" at the National Gallery of Art's East Building. Call 842-6271.

FILM HISTORY -- Friday marks the day in 1431 that 19-year-old Joan of Arc, found guilty of sorcery, was burned at the stake in Rouen, France. It was 66 years ago Friday that the Lincoln Memorial was dedicated. Stars celebrating birthdays on Friday include the man of 1,000 voices, Mel Blanc, who turns 78; Jazz musician Benny Goodman, 77; the world's first transsexual, Christine Jorgensen, 60; actor Clint Walker, 59; and actor Michael J. Pollard, 47.

Saturday marks the day in 1889 that more than 2,200 people lost their lives in Pennsylvania's Johnstown Flood. The catastrophe led to one of Hollywood's earliest disaster films, The Johnstown Flood, a 70-minute silent movie made in 1926 and starring Janet Gaynor in her first feature-length film.

Saturday's birthdays include this year's Best Supporting Actor, Don Ameche, who turns 78. He won the Oscar for his role as a senior citizen in a Florida retirement home who finds the fountain of youth in the movie Cocoon. Also celebrating birthdays on Saturday are Prince Rainier of Monaco, who turns 63; Clint Eastwood, mayor of Carmel-by-the-Sea, Calif., 56; singer Peter Yarrow, 48; former New York Jets quarterback-turned actor Joe Namath, 43; actor Tom Berenger, 36; actor Gregory Harrison, 36; and actress-model Brooke Shields, 21.

Sunday's celebrity birthdays include actor Andy Griffith, who turns 60; singer Pat Boone, 52; and actor-comedian Cleavon Little, 47.