I dont know how to start the hk 51 quest

[HaganK]

so I'm a sith warrior I just became level 50 and the quest for hk 51 hasn't shown up I am a subscriber as well what's going on?

[Jagaimee]

Okay...the HK-51 quest chain? Or the HK-55 quest?

 

To get HK-51, you need to travel to Section X on Belsavis. There should be a droid nearby, when you get there, that will give you a [Heroic 2+] mission, and that starts the very long HK-51 quest chain, which includes a couple of solo (or tactical, or Hard Mode) flashpoints. Note that you can solo the entirety of the HK-51 quest chain, despite the "[Heroic: 2+]" mission markers all over the place. It might be a pain in the behind to do so at a few points, but it's more than doable.

...for a far better explanation than what I just said, here's Dulfy's guide on the quest (which is SUPER helpful, thank you Dulfy!): http://dulfy.net/2012/10/11/swtor-patch-1-5the-hunt-for-hk-51companion-droid/

 

To get HK-55, you need to have completed Chapters 1-10 (correct me if I'm wrong on that) of Knights of the Fallen Empire, which takes place after the expansion Shadow of Revan and the planet Ziost (those are highly recommended to complete if it's your first character going through those expansions, as they set up...basically everything for Fallen Empire). Shadow of Revan can be started at level 55. Ziost is only available after Shadow of Revan is completed. And Fallen Empire can be started at level 60.

Also, to be eligible to get the HK-55 quest, you needed to be a subscriber on a certain date. And I can't, for the life of me, remember what that date was right now. Dang it.

[ButeoRegalis]

To get to Section X, use one of the special shuttle terminals you can find on pretty much any of the end-game planets and space stations. The terminals look a little like the mission terminal on your ship and transport you to any of the daily areas. I don't think you can get to Section X any other way.

 

E.g. on the Makeb space station, the terminal is across from the GTN terminal, next to one of the daily/weekly terminals. On Belsalvis, when you step off the shuttle, go down one level and the terminal is right next to the stairs, close to the shuttle.