I thought I responded to this when you first posted it a while back. The organization referred to was the 3502d Base Unit, Army Air Forces (Technical School). This was a training unit permanently assigned at Chanute and had nothing to do with helicopters. The "expert" who gave you your "best answer so far" obviously adhers to the ages-old practice of "if you don't know the answer, make one up". This is common among "experts" (and is one of the main reasons I hope never to become one).