[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR25.103]

[Page 351-352]
 
                     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 352]]

    (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]