[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: 14CFR25.331]



[Page 370-371]

 

                     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. 25.331  Symmetric maneuvering conditions.



    (a) Procedure. For the analysis of the maneuvering flight conditions 

specified in paragraphs (b) and (c) of this section, the following 

provisions apply:

    (1) Where sudden displacement of a control is specified, the assumed 

rate of control surface displacement may not be less than the rate that 

could be applied by the pilot through the control system.

    (2) In determining elevator angles and chordwise load distribution 

in the maneuvering conditions of paragraphs (b) and (c) of this section, 

the effect of corresponding pitching velocities must be taken into 

account. The in-trim and out-of-trim flight conditions specified in 

Sec. 25.255 must be considered.



[[Page 371]]



    (b) Maneuvering balanced conditions. Assuming the airplane to be in 

equilibrium with zero pitching acceleration, the maneuvering conditions 

A through I on the maneuvering envelope in Sec. 25.333(b) must be 

investigated.

    (c) Pitch maneuver conditions. The conditions specified in 

paragraphs (c)(1) and (2) of this section must be investigated. The 

movement of the pitch control surfaces may be adjusted to take into 

account limitations imposed by the maximum pilot effort specified by 

Sec. 25.397(b), control system stops and any indirect effect imposed by 

limitations in the output side of the control system (for example, 

stalling torque or maximum rate obtainable by a power control system.)

    (1) Maximum pitch control displacement at VA. The 

airplane is assumed to be flying in steady level flight (point 

A1, Sec. 25.333(b)) and the cockpit pitch control is 

suddenly moved to obtain extreme nose up pitching acceleration. In 

defining the tail load, the response of the airplane must be taken into 

account. Airplane loads that occur subsequent to the time when normal 

acceleration at the c.g. exceeds the positive limit maneuvering load 

factor (at point A2 in Sec. 25.333(b)), or the resulting 

tailplane normal load reaches its maximum, whichever occurs first, need 

not be considered.

    (2) Specified control displacement. A checked maneuver, based on a 

rational pitching control motion vs. time profile, must be established 

in which the design limit load factor specified in Sec. 25.337 will not 

be exceeded. Unless lesser values cannot be exceeded, the airplane 

response must result in pitching accelerations not less than the 

following:

    (i) A positive pitching acceleration (nose up) is assumed to be 

reached concurrently with the airplane load factor of 1.0 (Points 

A1 to D1, Sec. 25.333(b)). The positive 

acceleration must be equal to at least

[GRAPHIC] [TIFF OMITTED] TC28SE91.033



where--



n is the positive load factor at the speed under consideration, and V is 

the airplane equivalent speed in knots.



    (ii) A negative pitching acceleration (nose down) is assumed to be 

reached concurrently with the positive maneuvering load factor (points 

A2 to D2, Sec. 25.333(b)). This negative pitching 

acceleration must be equal to at least

[GRAPHIC] [TIFF OMITTED] TC28SE91.034



where--



n is the positive load factor at the speed under consideration; and V is 

the airplane equivalent speed in knots.



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

35 FR 5672, Apr. 8, 1970; Amdt. 25-46, 43 FR 50594, Oct. 30, 1978; 43 FR 

52495, Nov. 13, 1978; 43 FR 54082, Nov. 20, 1978; Amdt. 25-72, 55 FR 

29775, July 20, 1990; 55 FR 37607, Sept. 12, 1990; Amdt. 25-86, 61 FR 

5220, Feb. 9, 1996; Amdt. 25-91, 62 FR 40704, July 29, 1997]