Need Help for aeroplane scrip

Hi guys, for some reason my aeroplane script will not allow me to pitch upwards can you guys have alook at it thanks.

 var flyer : Transform;

var flyerRigidbody : Rigidbody; var seaLevelTransform : Transform;

// Assorted control variables. These mostly handle realism settings, change as you see fit. var accelerateConst: float = 5; // Set these close to 0 to smooth out acceleration. Don't set it TO zero or you will have a division by zero error. var decelerateConst: float = 0.065; // I found t$$anonymous$$s value gives semi-realistic deceleration, change as you see fit.

 /*    The ratio of MaxSpeed to Speed Const determines your true max speed. The formula is maxSpeed/SpeedConst = True Speed. 
     T$$anonymous$$s way you wont have to scale your objects to make them seem like they are going fast or slow.
     MaxSpeed is what you will want to use for a GUI though.
 */ 
 static var maxSpeed : float = 100;        
 var speedConst : float = 50;
 
 var throttleConst : int = 50;
 var raiseFlapRate : float = 1;                        // Smoother when close to zero
 var lowerFlapRate : float = 1;                        // Smoother when close to zero
 var maxAfterburner : float = 5;                // The maximum thrust your afterburner will produce
 var afterburnerAccelerate : float = 0.5;
 var afterburnerDecelerate : float = 1;
 var liftConst : float = 7.5;                    // Another arbitrary constant, change it as you see fit.
 var angleOfAttack : float = 15;            // Effective range: 0 <= angleOfAttack <= 20
 var gravityConst = 9.8;                // An arbitrary gravity constant, there is no particular reason it has to be 9.8...
 var levelFlightPercent : int = 25;
 var maxDiveForce : float = 0.1;
 var noseDiveConst : float = 0.01;
 var minSmooth : float = 0.5;
 var maxSmooth : float = 500;
 var maxControlSpeedPercent : float = 75;        // When your speed is withen the range defined by these two variables, your s$$anonymous$$p's rotation sensitivity fluxuates.
 var minControlSpeedPercent : float = 25;        // If you reach the speed defined by either of these, your s$$anonymous$$p has reached it's max or min sensitivity.

// Rotation Variables, change these to give the effect of flying anyt$$anonymous$$ng from a cargo plane to a fighter jet. var lockRotation : boolean; // If t$$anonymous$$s is checked, it locks pitch roll and yaw constants to the var rotationConst. var lockedRotationValue : int = 120; var pitchConst = 100; var rollConst = 100; var yawConst = 100;

// Airplane Aerodynamics - I strongly reccomend not touc$$anonymous$$ng these... private var nosePitch : float; private var trueSmooth : float; private var smoothRotation : float; private var truePitch : float; private var trueRoll : float; private var trueYaw : float; private var trueThrust : float; static var trueDrag : float;

// Misc. Variables static var afterburnerConst : float; static var altitude : int;

// HUD and Heading Variables. Use these to create your insturments. static var trueSpeed : int; static var attitude : int; static var incidence : int; static var bank : int; static var heading : int;

// Let the games begin! function Start () { trueDrag = 0; afterburnerConst = 0; smoothRotation = minSmooth + 0.01; if (lockRotation == true) { pitchConst = lockedRotationValue; rollConst = lockedRotationValue; yawConst = lockedRotationValue; Screen.showCursor = false; } }

function Update () {

 // * * T$$anonymous$$s section of code handles the plane's rotation.
 
 var pitch = -Input.GetAxis ("Pitch") * pitchConst;
 var roll = Input.GetAxis ("Roll") * rollConst;
 var yaw = -Input.GetAxis ("Yaw") * yawConst;

 pitch *=  Time.deltaTime;
 roll *= -Time.deltaTime;
 yaw *= Time.deltaTime;
 
 // Smot$$anonymous$$ng Rotations...    
 if ((smoothRotation > minSmooth)&&(smoothRotation < maxSmooth))
 {
     smoothRotation = Mathf.Lerp (smoothRotation, trueThrust, (maxSpeed-(maxSpeed/minControlSpeedPercent))* Time.deltaTime);
 }
 if (smoothRotation <= minSmooth)
 {
     smoothRotation = smoothRotation +0.01;
 }
 if ((smoothRotation >= maxSmooth) &&(trueThrust < (maxSpeed*(minControlSpeedPercent/100))))
 {
     smoothRotation = smoothRotation -0.1;
 }
 trueSmooth = Mathf.Lerp (trueSmooth, smoothRotation, 5* Time.deltaTime);
 truePitch = Mathf.Lerp (truePitch, pitch, trueSmooth * Time.deltaTime);
 trueRoll = Mathf.Lerp (trueRoll, roll, trueSmooth * Time.deltaTime);
 trueYaw = Mathf.Lerp (trueYaw, yaw, trueSmooth * Time.deltaTime);



 

// T$$anonymous$$s next block handles the thrust and drag. var throttle = (((-(Input.GetAxis ("Throttle"))+1)/2)*100);

 if ( throttle/speedConst >= trueThrust)
 {
     trueThrust = Mathf.SmoothStep (trueThrust, throttle/speedConst, accelerateConst * Time.deltaTime);
 }
 if (throttle/speedConst < trueThrust)
 {
     trueThrust = Mathf.Lerp (trueThrust, throttle/speedConst, decelerateConst * Time.deltaTime);
 }    

 rigidbody.drag = liftConst*((trueThrust)*(trueThrust));
 
 if (trueThrust <= (maxSpeed/levelFlightPercent))
 {
     
     nosePitch = Mathf.Lerp (nosePitch, maxDiveForce, noseDiveConst * Time.deltaTime);
 }
 else
 {
     
     nosePitch = Mathf.Lerp (nosePitch, 0, 2* noseDiveConst * Time.deltaTime);
 }
 
 trueSpeed = ((trueThrust/2)*maxSpeed);
 

// ** Additional Input

 // Airbrake
 if (Input.GetButton ("Airbrake"))
 {
     trueDrag = Mathf.Lerp (trueDrag, trueSpeed, raiseFlapRate * Time.deltaTime);        
     
 }
 
 if ((!Input.GetButton ("Airbrake"))&&(trueDrag !=0))
 {
     trueDrag = Mathf.Lerp (trueDrag, 0, lowerFlapRate * Time.deltaTime);
 }
 
 
 // Afterburner
 if (Input.GetButton ("Afterburner"))
 {
     afterburnerConst = Mathf.Lerp (afterburnerConst, maxAfterburner, afterburnerAccelerate * Time.deltaTime);        
 }
 
 if ((!Input.GetButton ("Afterburner"))&&(afterburnerConst !=0))
 {
     afterburnerConst = Mathf.Lerp (afterburnerConst, 0, afterburnerDecelerate * Time.deltaTime);
 }
 
 
 // Adding nose dive when speed gets below a percent of your max speed    
 if ( ((trueSpeed - trueDrag) + afterburnerConst) <= (maxSpeed*levelFlightPercent/100))
 {
     noseDiveConst = Mathf.Lerp (noseDiveConst,maxDiveForce, (((trueSpeed - trueDrag) + afterburnerConst) - (maxSpeed * levelFlightPercent/100)) *5 *Time.deltaTime);
     flyer.Rotate(noseDiveConst,0,0,Space.World);        
 }
 
 
 // Calculating Flight Mechanics. Used mostly for the HUD.
 attitude = parseInt(-((Vector3.Angle(Vector3.up, flyer.forward))-90));
 bank = parseInt(((Vector3.Angle(Vector3.up, flyer.up))));    
 incidence = attitude + angleOfAttack;
 heading = parseInt(flyer.eulerAngles.y);
 
 if ( seaLevelTransform != null )
 {
 altitude = (flyer.transform.position.y - seaLevelTransform.transform.position.y);
 }
 //Debug.Log ((((trueSpeed - trueDrag) + afterburnerConst) - (maxSpeed * levelFlightPercent/100)));

} // End function Update( );

function FixedUpdate () { if (trueThrust <= maxSpeed) { // Horizontal Force transform.Translate(0,0,((trueSpeed - trueDrag)/100 + afterburnerConst)); }

 flyerRigidbody.AddForce (0,(rigidbody.drag - gravityConst),0);
 transform.Rotate (truePitch,-trueYaw,trueRoll);