The pleas Wednesday could bring LeBlanc 15 years imprisonment and a dishonorable discharge. He is fighting other allegations in court that could double his jail time, the San Antonio Express-News reported.
LeBlanc is accused of nine charges and 12 specifications of misconduct, including the sexual assault of a woman after she graduated from basic training, and is one of 32 basic training instructors charged in an ongoing scandal at the base, the newspaper said.
The U.S. Air Force reported Wednesday the number of victims in the scandal had risen from 59 to 62 recruits and technical training students, all but three of whom are women.
The guilty pleas Wednesday concerned an incident of sex with a basic training recruit, and an affair LeBlanc called "open and notorious" with a technical school student. the newspaper said.
"I completely disrespected my wife and my marriage," LeBlanc said during the proceedings.