[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR25.251]

[Page 361]
 
                     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. 25.251  Vibration and buffeting.

    (a) The airplane must be demonstrated in flight to be free from any 
vibration and buffeting that would prevent continued safe flight in any 
likely operating condition.
    (b) Each part of the airplane must be demonstrated in flight to be 
free from excessive vibration under any appropriate speed and power 
conditions up to VDF/MDF. The maximum speeds shown 
must be used in establishing the operating limitations of the airplane 
in accordance with Sec. 25.1505.
    (c) Except as provided in paragraph (d) of this section, there may 
be no buffeting condition, in normal flight, including configuration 
changes during cruise, severe enough to interfere with the control of 
the airplane, to cause excessive fatigue to the crew, or to cause 
structural damage. Stall warning buffeting within these limits is 
allowable.
    (d) There may be no perceptible buffeting condition in the cruise 
configuration in straight flight at any speed up to VMO/
MMO, except that stall warning buffeting is allowable.
    (e) For an airplane with MD greater than .6 or with a 
maximum operating altitude greater than 25,000 feet, the positive 
maneuvering load factors at which the onset of perceptible buffeting 
occurs must be determined with the airplane in the cruise configuration 
for the ranges of airspeed or Mach number, weight, and altitude for 
which the airplane is to be certificated. The envelopes of load factor, 
speed, altitude, and weight must provide a sufficient range of speeds 
and load factors for normal operations. Probable inadvertent excursions 
beyond the boundaries of the buffet onset envelopes may not result in 
unsafe conditions.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 
35 FR 5671, Apr. 8, 1970; Amdt. 25-72, 55 FR 29775, July 20, 1990; Amdt. 
25-77, 57 FR 28949, June 29, 1992]