[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: 14CFR25.321]



[Page 370]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

PART 25_AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES--Table 

of Contents

 

                           Subpart C_Structure

 

Sec. 25.321  General.



    (a) Flight load factors represent the ratio of the aerodynamic force 

component (acting normal to the assumed longitudinal axis of the 

airplane) to the weight of the airplane. A positive load factor is one 

in which the aerodynamic force acts upward with respect to the airplane.

    (b) Considering compressibility effects at each speed, compliance 

with the flight load requirements of this subpart must be shown--

    (1) At each critical altitude within the range of altitudes selected 

by the applicant;

    (2) At each weight from the design minimum weight to the design 

maximum weight appropriate to each particular flight load condition; and

    (3) For each required altitude and weight, for any practicable 

distribution of disposable load within the operating limitations 

recorded in the Airplane Flight Manual.

    (c) Enough points on and within the boundaries of the design 

envelope must be investigated to ensure that the maximum load for each 

part of the airplane structure is obtained.

    (d) The significant forces acting on the airplane must be placed in 

equilibrium in a rational or conservative manner. The linear inertia 

forces must be considered in equilibrium with the thrust and all 

aerodynamic loads, while the angular (pitching) inertia forces must be 

considered in equilibrium with thrust and all aerodynamic moments, 

including moments due to loads on components such as tail surfaces and 

nacelles. Critical thrust values in the range from zero to maximum 

continuous thrust must be considered.



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

35 FR 5672, Apr. 8, 1970; Amdt. 25-86, 61 FR 5220, Feb. 9, 1996]



                   Flight Maneuver and Gust Conditions