If you want to get the first column everytime then in my opinion, you have to check whether i is equl to zero the first time and then move accordingly.:
i=i+4
Next
When the i starts as 0, it is going to take : KM51124844G01 as a value
when you assign the i = i+4 then the i is going to count 4 more positions in the array depending on how many items the array has. For the second assembly after 4 positions it is going to have KM400740009G02 as a value. Again.... it is important to mention that this will only work only if for each Line:
KM51124844G01| 1.000 PC|FLAT CABLE FIXING ASSY,IMC SLING|1001.47|
the array is reserve 4 values per line.
I really hope this will help you!