3D Space thruster force problem.

Simple spaceflight force, it needs tweaking.. But my problem is that it always adds the force applied relative to world, and not local rotation. How can I fix that?

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(Rigidbody))]
 public class PhysicsFlyer : MonoBehaviour
 {
     public float maxThrust = 15f;
     public float maxStrafe = 10f;
     public float engineForce = 2f;
     public float maxVelocityChange = 2f;
     public float accelerationSmooth = 20;
 
     private Vector3 velocityChange;
 
     void FixedUpdate()
     {
         velocityChange = new Vector3(Input.GetAxis("Horizontal") * engineForce, Input.GetAxis("Vertical") * engineForce, 0);
         if (velocityChange.magnitude > 1)
             velocityChange = velocityChange.normalized;
         velocityChange += new Vector3(0, 0, Input.GetAxis("Mouse ScrollWheel") * engineForce * 10);
         velocityChange.x = Mathf.Clamp(velocityChange.x, -maxStrafe, maxStrafe);
         velocityChange.y = Mathf.Clamp(velocityChange.y, -maxStrafe, maxStrafe);
         velocityChange.z = Mathf.Clamp(velocityChange.z, -maxThrust, maxThrust);
 
         rigidbody.AddForce(velocityChange, ForceMode.VelocityChange);
     }
 }