Its the Ai CPG clicking the Slave button on the TEDAC. In order for me not to hear it after shutdown I make sure that the George Ai is Unslaved before shutting down. I know I am like nearly 2 years late to this convo but yeah... thats the answer lol.
Edit: if its not the slave button it might be another TEDAC button that the Ai is pressing so just fiddle with the George Ai and before shutting down and you will come right