Read all about the knights of the Empire in the Knightly Orders Guide.
...since the 6th edition HBVG hit automatically.
Good for you! It hit automatically, but the number of hits were halved at long range.
As Warlord said, not in 6th, where an Engineer could only serve as an extra crewman. It would not have made a difference either, since the 6th edition HBVG hit automatically. The 7th AB changed that - not for the better, and I never took it in 7th.