CTD in Beech King Air when I go
to descend.
If you want help, it might be easier if you give more detail.
I was in cruise level and decide to travel to phase of descend; and when I was on descend, all began to fail: AP, speed plummeted… The aircraft was uncontrollable.
A CTD is something completely different from what you are describing now.
A panel screenshot might help with troubleshooting.