Internal frame packs are generally characterized by having several various sized pocket compartments into which a metal support frame is placed.  Typically, tubular sleeves are sewn onto the inside of the largest, lower compartment of the pack into which metal strips or stays are slidably, placed.  The stays are commonly made of high grade aluminum which is bent to the vertical contours of the wearers back.  Usually the stays are attached onto a sheet of plastic which provides a rigid surface.  On the outside of this rigid surface the shoulder straps and waist belt are attached, so that the weight of the load in the pack is transferred to the waist belt of the user, and not the shoulders.  An important benefit of an internal frame pack is that it fits closely to the body of the user.  This close fit provides a low center of gravity, and the separate strips or stays of the internal frame allow the pack to move with the user (torsional flex). 
U.S. Pat.  No.  8,678,258 discloses a vertically and horizontally flexible backpack back support frame having a Y-shaped configuration to conform to the shape of a back of a user.  The back support frame is attached to the back of a backpack by inserting it into a pocket on the back of backpack.  Backpack straps, belts, and padding attach reversibly and pivotably to the back support frame when the back support frame is in the pocket.  However, to remove the back support frame from the pocket the straps and belts need to be removed first. 
What is needed is an attachment system for the back support frame which does not require the use of a pocket and which allows the support frame to be removed from the backpack without the need to remove belts, straps, and padding from the support frame.