Stephanie Hayden -- Collapses After Dr. Phil Taping

'Sons of Guns' star Stephanie Hayden opened up to Dr. Phil about her father allegedly raping her and her sister -- and seconds after the interview she fainted and blacked out.

Stephanie sat down with Dr. Phil last week in Los Angeles -- and sources tell us Stephanie fell unconscious into her husband's arms as she walked away from the interview.

We're told someone called 911, but Stephanie had regained consciousness by the time EMTs arrived.
She had mentioned being stressed about discussing Will Hayden's rape case.

As for the interview ... we're told she divulged details for the first time ... about the abuse she claims to have suffered.

The interview airs Thursday. Her father remains behind bars.