Dell PowerEdge C6220 Hardware Owner's Manual page 209

Figure 3-64. Removing and Installing the Upper Middle Plane
1 screw (8) 2 upper middle plane
13 Remove the screws that secure the mid-plane holder support to the
chassis. See Figure 3-65.
14 Lift the mid-plane holder support out of the chassis. See Figure 3-65.
Installing System Components | 209