User blog comment:Nintendogeek01/What's your favorite ME3 Normandy moment?/@comment-2127131-20120623090404/@comment-2127131-20120623160607

It's a bug. The criteria for all of the engine room chatter can on;y be heard if you are good friends with Ash, so if you have Kaidan in your playthrough you won't be able to hear it. Unless you do something with the game save.