EDIT: OH FOR FOOKS SAKE ALL THE IMAGES HAVE NOT COME OUT IN THE POSITION OF THE POST THEY WERE SUPPOSED TO…SORRY ABOUT THAT.
If you have a flying object like a ship or plane rather than a flying humanoid character its probably easier and better to just make your own flying version from a standard pawn if you want full 360 rotation. It probably takes less effort than using the flying mode and trying to understand what all that does. Plus you don’t get those problems you seem to be having with turning at high speeds.
Unfortunately I’m not at my computer to put an image of my blueprints up but basically I fire an event in the pawns tick that controls the movement applied by the input (don’t put the input itself in the pawn put it in the player controller so the AI can use the pawn aswell without you having to make a specific AI version, then pass the input from the controller to the pawn).
I’ll try to write a simple walkthrough to get you started, I can always show you my blueprints when I get home later on. (in fact I’ve just managed to install UE4 on a rather splendidly **** computer so i’ll post some screenshots, bear in mind though these arn’t my blueprints they’re just me doing them as I write this as a visual aid)
you’ll need some float variables in your pawn:
-Pitch Input
-Yaw Input
-Roll Input
-Thrust Input
-Pitch Speed
-Yaw Speed
-Roll Speed (optional if you want the roll speed to be different to the turn speed)
-Thrust speed (personally I make a throttle that does some calculations to get the thrust speed but for simplicities sake we’ll just use a constant value)
-Assign default values to pitch speed, yaw speed, roll speed, thrust speed
The general idea is that input values read from 0 to 1, you then multiple the input value by the (for example) pitch speed to get the amount of pitch applied, then add this value to the pawn by using either the blueprint node ‘SetTorque’ or alternatively (and the one I use as it seems to work better) ‘setAngularVelocity’. All the variables ‘pitch speed’, ‘roll speed’ etc are essentially the maximum amount of turn that can be applied per frame, so if the player was holding the pitch axis on the controller all the way down the pitch input value would be returning the value of ‘1’, which applied to the ‘pitch speed’ would give you the maximum pitching speed.
Hope this waffle is making sense so far…
We’ll do the player controller first:
-Create your axis and button mappings in the project settings. Surprisingly I don’t have a joystick/gamepad at work so I’ve just mapped keyboard controls 
-Create the input events in your controller blueprint and send the values to the pawn. I also have a pawn reference variable that gets set at ‘Begin Play’ in the player controller that you’ll need to cast to as you’ll need that to send the custom input values to your custom pawn.
e.g.
Get the pitch axis input then store that value in the pawns variable ‘pitch input’
-Do that for all your axis and buttons
Now to the pawn:
-Create a function (you can do an event instead but I prefer functions to keep it clean and manageable) called something like ‘SetTurnMovement’.
-Open the function and in here you’ll do all the code for turning the ship
-You basically want to create a vector that is made from the values of pitch, yaw and roll then add them to a node that uses physics to turn the flying object. Worth ticking that ‘add to current’ on the ‘Set Physics Angular Velocity’ node to begin with as you’ll probably find your values are to low to move the object and it’ll look like nothing is working, that’ll take some tweaking so best to start from a place where the ship actually turns so you know it’s all working before you fine tune the values.
Now in the main blueprint of your pawn add a ‘tick’ event and make that fire the function you just created:
-Also make sure that in the components part of the pawn blueprint you set the component that is moving (i assume a static or skeletal mesh) is set to ‘simulate physics’. Also you’ll find all the other settings you need in there to control the handling of the flying object at the physics level, for example angular damping which will make it harder to turn/slow the ship down quicker when turning. All the inertia and spacey movement type stuff basically.
I can’t be bothered in all honesty to do the thrust aswell as it’s now lunch time I’ve spent so long putting this together, it’s just the same thing as the turning function but put in your ‘thrust input’ and ‘thrust speed’. Also instead of ‘Set Physics Angular Velocity’ node use either the ‘add impulse’ or ‘set physics linear velocity’ nodes.
