At the end of "The Delta Discovery," the Phantom Ranger leaves two messages for the Rangers—one to let them know he's continuing the search for Zordon and the other one specifically for Cassie.
"I'll be alright, Cassie. Please, don't forget me. I'll see you soon!"
"From Out of Nowhere, Part 2", as Andros repairs Alpha 6's damaged voice.
Andros: Alpha, what is your mission? Alpha 6: My mission is to protect the Power Rangers. And their quest: to protect the universe from the forces of evil. One goal, one team known as the Power Rangers!