failed HD in RAID 5 array

I can’t seem to find a solid answer to my problem. I had a disk fail in a RAID 5 array. After putting in the new disk, the system refuses to add the disk to the array. I can’t get it to do it manually, and it didn’t do it automatically. The disks are non hot-swappable SCSI drives. The SCSI BIOS does give me the option of making the drive a hot swap. Is there a way I should be adding the drive to the array manually, or should I just make the new drive a hot swap?