[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: 14CFR23.177]

[Page 192]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 23--AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES--Table of Contents
 
                            Subpart B--Flight
 
Sec. 23.177  Static directional and lateral stability.

    (a) The static directional stability, as shown by the tendency to 
recover from a wings level sideslip with the rudder free, must be 
positive for any landing gear and flap position appropriate to the 
takeoff, climb, cruise, approach, and landing configurations. This must 
be shown with symmetrical power up to maximum continuous power, and at 
speeds from 1.2 VS1 up to the maximum allowable speed for the 
condition being investigated. The angel of sideslip for these tests must 
be appropriate to the type of airplane. At larger angles of sideslip, up 
to that at which full rudder is used or a control force limit in 
Sec. 23.143 is reached, whichever occurs first, and at speeds from 1.2 
VS1 to VO, the rudder pedal force must not 
reverse.
    (b) The static lateral stability, as shown by the tendency to raise 
the low wing in a sideslip, must be positive for all landing gear and 
flap positions. This must be shown with symmetrical power up to 75 
percent of maximum continuous power at speeds above 1.2 VS1 
in the take off configuration(s) and at speeds above 1.3 VS1 
in other configurations, up to the maximum allowable speed for the 
configuration being investigated, in the takeoff, climb, cruise, and 
approach configurations. For the landing configuration, the power must 
be that necessary to maintain a 3 degree angle of descent in coordinated 
flight. The static lateral stability must not be negative at 1.2 
VS1 in the takeoff configuration, or at 1.3 VS1 in 
other configurations. The angle of sideslip for these tests must be 
appropriate to the type of airplane, but in no case may the constant 
heading sideslip angle be less than that obtainable with a 10 degree 
bank, or if less, the maximum bank angle obtainable with full rudder 
deflection or 150 pound rudder force.
    (c) Paragraph (b) of this section does not apply to acrobatic 
category airplanes certificated for inverted flight.
    (d) In straight, steady slips at 1.2 VS1 for any landing 
gear and flap positions, and for any symmetrical power conditions up to 
50 percent of maximum continuous power, the aileron and rudder control 
movements and forces must increase steadily, but not necessarily in 
constant proportion, as the angle of sideslip is increased up to the 
maximum appropriate to the type of airplane. At larger slip angles, up 
to the angle at which full rudder or aileron control is used or a 
control force limit contained in Sec. 23.143 is reached, the aileron and 
rudder control movements and forces must not reverse as the angle of 
sideslip is increased. Rapid entry into, and recovery from, a maximum 
sideslip considered appropriate for the airplane must not result in 
uncontrollable flight characteristics.

[Doc. No. 27807, 61 FR 5190, Feb. 9, 1996]