When I googled A320 P2F I found the following extract from "Air Cargo World":
>The technical challenge for EFW was resolving the issue of where to put the cargo door without aggravating the A320’s forward centre of gravity issue.
Aircraft stability involves balancing a number of factors including the centre of gravity (CG) and centre of pressure.
EFW’s head of aircraft conversion sales, Andreas Mayer, spoke to ACW and says: “We had the problem of a design decision to put a cargo door in the back, the A320 has a forward centre of gravity issue and putting structural reinforcement in the rear we would have cured that problem, but we created new problems by putting in a door at the rear because the structure was very weak at that area and we had to reinforce to a much greater extent and we were required to do a full fatigue test. Then we realised the aircraft is going into an unstable state, flutter, and it created…new technical challenges.”<
>Mayer explains: “We now have the door in the front. Our cargo door location is at two different locations for the A320 and A321, so we do not have the door in the same position.
“On the A321 it is further back due to the forward CG issue. We are trying to put the door as far back as possible without reducing loading clearance for the engine nacelle.”<
Does anyone know what the forward CG issue was/is? The text suggests it may be specific to a freighter version