[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: 14CFR25.253]



[Page 367-368]

 

                     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. 25.253  High-speed characteristics.



    (a) Speed increase and recovery characteristics. The following speed 

increase and recovery characteristics must be met:

    (1) Operating conditions and characteristics likely to cause 

inadvertent speed increases (including upsets in pitch and roll) must be 

simulated with the airplane trimmed at any likely cruise speed up to 

VMO/MMO. These conditions and characteristics include gust upsets, 

inadvertent control movements, low stick force gradient in relation to 

control friction, passenger movement, leveling off from climb, and 

descent from Mach to airspeed limit altitudes.

    (2) Allowing for pilot reaction time after effective inherent or 

artificial speed warning occurs, it must be shown



[[Page 368]]



that the airplane can be recovered to a normal attitude and its speed 

reduced to VMO/MMO, without-

    (i) Exceptional piloting strength or skill;

    (ii) Exceeding VD/MD, VDF/MDF, or the structural limitations; and

    (iii) Buffeting that would impair the pilot's ability to read the 

instruments or control the airplane for recovery.

    (3) With the airplane trimmed at any speed up to VMO/

MMO, there must be no reversal of the response to control 

input about any axis at any speed up to VDF/MDF. 

Any tendency to pitch, roll, or yaw must be mild and readily 

controllable, using normal piloting techniques. When the airplane is 

trimmed at VMO/MMO, the slope of the elevator 

control force versus speed curve need not be stable at speeds greater 

than VFC/MFC, but there must be a push force at 

all speeds up to VDF/MDF and there must be no 

sudden or excessive reduction of elevator control force as 

VDF/MDF is reached.

    (b) Maximum speed for stability characteristics, VFC/

MFC. VFC/MFC is the maximum speed at 

which the requirements of Sec. Sec. 25.143(f), 25.147(e), 25.175(b)(1), 

25.177, and 25.181 must be met with flaps and landing gear retracted. It 

may not be less than a speed midway between VMO/

MMO and VDF/MDF, except that for 

altitudes where Mach number is the limiting factor, MFC need 

not exceed the Mach number at which effective speed warning occurs.



[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 

35 FR 5671, Apr. 8, 1970; Amdt. 25-54, 45 FR 60172, Sept. 11, 1980; 

Amdt. 25-72, 55 FR 29775, July 20, 1990; Amdt. 25-84, 60 FR 30750, June 

9, 1995]