The aircraft will load up in a 'ready for takeoff' state unless:

• You are loading a previously saved Arrow III flight, in which case the aircraft configuration will be restored to what it was when that flight was saved
• You are switching from another aircraft with the engine off, in which case the aircraft will be configured in a cold & dark state
• You have enabled cockpit state saving from the Add-ons > Just Flight PA28R Arrow III menu within the simulator, in which case the aircraft configuration will be restored to what it was when you last flew the Arrow III

You can switch to a cold & dark state using the power icon on the 2D panel selector or the 'Cold and dark' option in the menu bar.