The A frame is the piece on top of the fuselage sticking up in the air like a big finger. There are actually two of them required on the fuselage to support the huge wings. You can see quite clearly in the other pictures where the wings are attached, how important they are to the plane's structure.
2726 Yorks Cor Rd.
RR1 Metcalfe, Ont, KOA 2PO