Remove custom packet send to server for part placement since this is triggered again on the server automatically by forge.

src/main/java/appeng/items/parts/ItemMultiPart.java

@@ -168,7 +168,7 @@ public final class ItemMultiPart extends AEBaseItem implements IPartItem, IItemG
 	{
 		if( this.getTypeByStack( is ) == PartType.InvalidType )
 		{
-			return EnumActionResult.PASS;
+			return EnumActionResult.FAIL;
 		}
 
 		return AEApi.instance().partHelper().placeBus( is, pos, side, player, hand, w );

src/main/java/appeng/parts/PartPlacement.java

@@ -399,7 +399,6 @@ public class PartPlacement
 		else
 		{
 			player.swingArm( hand );
-			NetworkHandler.instance.sendToServer( new PacketPartPlacement( pos, side, getEyeOffset( player ), hand ) );
 		}
 		return EnumActionResult.SUCCESS;
 	}