Gloria Winters, who personified youthful, clean-cut American innocence in the 1950s children’s television series “Sky King,” died Aug. 14 at her home in Vista, Calif., just north of San Diego. She was in her late 70s.

The cause was complications of pneumonia, her family told The Los Angeles Times.

“Sky King” was a contemporary Western about an Arizona rancher and pilot, the title character, who ran into the likes of jewel smugglers, bank robbers and gangsters. Winters played Sky’s blond, baby-faced, perky but earnest and unfailingly helpful teenage niece, Penny, who often became involved in the adventures.

She played the role in 72 episodes from 1952 to 1959. (Kirby Grant, who played Sky King, died in 1985.)

Although she retired from show business after “Sky King” went off the air, during its run Winters also did guest acting roles in numerous 1950s series, including “Richard Diamond, Private Detective,” “Racket Squad” and “Death Valley Days.” She had made her credited television debut as Babs, the dreamy-eyed teenage daughter, in the first season (1949-50) of the working-class sitcom “The Life of Riley,” when Jackie Gleason played Riley. William Bendix played the role in later seasons.