[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: 14CFR27.427]

[Page 547]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 27--AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT--Table of Contents
 
                    Subpart C--Strength Requirements
 
Sec. 27.427  Unsymmetrical loads.

    (a) Horizontal tail surfaces and their supporting structure must be 
designed for unsymmetrical loads arising from yawing and rotor wake 
effects in combination with the prescribed flight conditions.
    (b) To meet the design criteria of paragraph (a) of this section, in 
the absence of more rational data, both of the following must be met:
    (1) One hundred percent of the maximum loading from the symmetrical 
flight conditions acts on the surface on one side of the plane of 
symmetry, and no loading acts on the other side.
    (2) Fifty percent of the maximum loading from the symmetrical flight 
conditions acts on the surface on each side of the plane of symmetry but 
in opposite directions.
    (c) For empennage arrangements where the horizontal tail surfaces 
are supported by the vertical tail surfaces, the vertical tail surfaces 
and supporting structure must be designed for the combined vertical and 
horizontal surface loads resulting from each prescribed flight 
condition, considered separately. The flight conditions must be selected 
so the maximum design loads are obtained on each surface. In the absence 
of more rational data, the unsymmetrical horizontal tail surface loading 
distributions described in this section must be assumed.

[Admt. 27-26, 55 FR 7999, Mar. 6, 1990, as amended by Amdt. 27-27, 55 FR 
38966, Sept. 21, 1990]

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