[Code of Federal Regulations]

[Title 14, Volume 1]

[Revised as of January 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 14CFR25.103]



[Page 349-350]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

PART 25_AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES--Table 

of Contents

 

                            Subpart B_Flight

 

Sec. 25.103  Stall speed.



    (a) The reference stall speed, VSR, is a calibrated 

airspeed defined by the applicant. VSR may not be less than a 

1-g stall speed. VSR is expressed as:

[GRAPHIC] [TIFF OMITTED] TR26NO02.001



where:

VCLMAX = Calibrated airspeed obtained when the load factor-

corrected lift coefficient

[GRAPHIC] [TIFF OMITTED] TR26NO02.002



    is first a maximum during the maneuver prescribed in paragraph (c) 

of this section. In addition, when the maneuver is limited by a device 

that abruptly pushes the nose down at a selected angle of attack (e.g., 

a stick pusher), VCLMAX may not be less than the speed 

existing at the instant the device operates;

nZW = Load factor normal to the flight path at 

VCLMAX

W = Airplane gross weight;

S = Aerodynamic reference wing area; and

q = Dynamic pressure.



    (b) VCLMAX is determined with:

    (1) Engines idling, or, if that resultant thrust causes an 

appreciable decrease in stall speed, not more than zero thrust at the 

stall speed;

    (2) Propeller pitch controls (if applicable) in the takeoff 

position;

    (3) The airplane in other respects (such as flaps and landing gear) 

in the condition existing in the test or performance standard in which 

VSR is being used;

    (4) The weight used when VSR is being used as a factor to 

determine compliance with a required performance standard;

    (5) The center of gravity position that results in the highest value 

of reference stall speed; and

    (6) The airplane trimmed for straight flight at a speed selected by 

the applicant, but not less than 1.13VSR and not greater than 

1.3VSR.



[[Page 350]]



    (c) Starting from the stabilized trim condition, apply the 

longitudinal control to decelerate the airplane so that the speed 

reduction does not exceed one knot per second.

    (d) In addition to the requirements of paragraph (a) of this 

section, when a device that abruptly pushes the nose down at a selected 

angle of attack (e.g., a stick pusher) is installed, the reference stall 

speed, VSR, may not be less than 2 knots or 2 percent, 

whichever is greater, above the speed at which the device operates.



[Doc. No. 28404, 67 FR 70825, Nov. 26, 2002]