14 CFR 25.177 - Static lateral-directional stability.

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There are 12 Updates appearing in the Federal Register for 14 CFR 25. View below or at eCFR (GPOAccess)
§ 25.177 Static lateral-directional stability.
(a) The static directional stability (as shown by the tendency to recover from a skid with the rudder free) must be positive for any landing gear and flap position and symmetric power condition, at speeds from 1.13 VSR1, up to VFE, VLE, or VFC/MFC (as appropriate for the airplane configuration).
(b) The static lateral stability (as shown by the tendency to raise the low wing in a sideslip with the aileron controls free) for any landing gear and flap position and symmetric power condition, may not be negative at any airspeed (except that speeds higher than VFE need not be considered for flaps extended configurations nor speeds higher than VLE for landing gear extended configurations) in the following airspeed ranges:
(1) From 1.13 VSR1 to VMO/MMO.
(2) From VMO/MMO to VFC/MFC, unless the divergence is—
(i) Gradual;
(ii) Easily recognizable by the pilot; and
(iii) Easily controllable by the pilot.
(c) The following requirement must be met for the configurations and speed specified in paragraph (a) of this section. In straight, steady sideslips over the range of sideslip angles appropriate to the operation of the airplane, the aileron and rudder control movements and forces must be substantially proportional to the angle of sideslip in a stable sense. This factor of proportionality must lie between limits found necessary for safe operation. The range of sideslip angles evaluated must include those sideslip angles resulting from the lesser of:
(1) One-half of the available rudder control input; and
(2) A rudder control force of 180 pounds.
(d) For sideslip angles greater than those prescribed by paragraph (c) of this section, up to the angle at which full rudder control is used or a rudder control force of 180 pounds is obtained, the rudder control forces may not reverse, and increased rudder deflection must be needed for increased angles of sideslip. Compliance with this requirement must be shown using straight, steady sideslips, unless full lateral control input is achieved before reaching either full rudder control input or a rudder control force of 180 pounds; a straight, steady sideslip need not be maintained after achieving full lateral control input. This requirement must be met at all approved landing gear and flap positions for the range of operating speeds and power conditions appropriate to each landing gear and flap position with all engines operating.
[Amdt. 25-135, 76 FR 74654, Dec. 1, 2011]

Title 14 published on 2014-01-01

The following are only the Rules published in the Federal Register after the published date of Title 14.

For a complete list of all Rules, Proposed Rules, and Notices view the Rulemaking tab.

  • 2014-04-18; vol. 79 # 75 - Friday, April 18, 2014
    1. 79 FR 21845 - Installed Systems and Equipment for Use by the Flightcrew; Correction
      GPO FDSys XML | Text
      DEPARTMENT OF TRANSPORTATION, Federal Aviation Administration
      Final rule; corrections.
      This correction is effective April 18, 2014.
      14 CFR Part 25

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United States Code

Title 14 published on 2014-01-01

The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 14 CFR 25 after this date.

  • 2014-04-18; vol. 79 # 75 - Friday, April 18, 2014
    1. 79 FR 21845 - Installed Systems and Equipment for Use by the Flightcrew; Correction
      GPO FDSys XML | Text
      DEPARTMENT OF TRANSPORTATION, Federal Aviation Administration
      Final rule; corrections.
      This correction is effective April 18, 2014.
      14 CFR Part 25