[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: 14CFR27.339]

[Page 545]
 
                     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. 27.339  Resultant limit maneuvering loads.

    The loads resulting from the application of limit maneuvering load 
factors are assumed to act at the center of each rotor hub and at each 
auxiliary lifting surface, and to act in directions, and with 
distributions of load among the rotors and auxiliary lifting surfaces, 
so as to represent each critical maneuvering condition, including power-
on and power-off flight with the maximum design rotor tip speed ratio. 
The rotor tip speed ratio is the ratio of the rotorcraft flight velocity 
component in the plane of the rotor disc to the rotational tip speed of 
the rotor blades, and is expressed as follows:
[GRAPHIC] [TIFF OMITTED] TC28SE91.083

where--

V= The airspeed along flight path (f.p.s.);
a= The angle between the projection, in the plane of symmetry, of the 
axis of no feathering and a line perpendicular to the flight path 
(radians, positive when axis is pointing aft);
omega= The angular velocity of rotor (radians per second); and
R= The rotor radius (ft).

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27-11, 
41 FR 55469, Dec. 20, 1976]