The 20-year-old, who made his senior United debut in last November's Europa League clash with Astana, embarks on his first temporary move away from the club.
The centre-back will be hoping to impress and receive regular game-time with the Ammies, who have made an unbeaten start to their League Two campaign.
Bernard has featured in all of the Under-23s' five games this season including the EFL Trophy victory over his new club in the team's opening fixture of the campaign.
The move is United’s seventh outward loan from the Professional Development Phase during the window as the Academy continues to prioritise individual player development and give younger players the opportunity to prove themselves in Premier League 2.