[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: 14CFR25.147]

[Page 353-354]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES--Table of Contents
 
                            Subpart B--Flight
 
Sec. 25.147  Directional and lateral control.

    (a) Directional control; general. It must be possible, with the 
wings level, to yaw into the operative engine and to safely make a 
reasonably sudden change in heading of up to 15 degrees in the direction 
of the critical inoperative engine. This must be shown at 1.3 
VSR1 for heading changes up to 15 degrees (except that the 
heading change at which the rudder pedal force is 150 pounds need not be 
exceeded), and with--
    (1) The critical engine inoperative and its propeller in the minimum 
drag position;
    (2) The power required for level flight at 1.3 VSR1, but 
not more than maximum continuous power;
    (3) The most unfavorable center of gravity;
    (4) Landing gear retracted;
    (5) Flaps in the approach position; and
    (6) Maximum landing weight.
    (b) Directional control; airplanes with four or more engines. 
Airplanes with four or more engines must meet the requirements of 
paragraph (a) of this section except that--
    (1) The two critical engines must be inoperative with their 
propellers (if applicable) in the minimum drag position;
    (2) [Reserved]
    (3) The flaps must be in the most favorable climb position.
    (c) Lateral control; general. It must be possible to make 20 deg. 
banked turns, with and against the inoperative engine, from steady 
flight at a speed equal to 1.3 VSR1, with--
    (1) The critical engine inoperative and its propeller (if 
applicable) in the minimum drag position;
    (2) The remaining engines at maximum continuous power;
    (3) The most unfavorable center of gravity;
    (4) Landing gear (i) retracted and (ii) extended;
    (5) Flaps in the most favorable climb position; and
    (6) Maximum takeoff weight.
    (d) Lateral control; airplanes with four or more engines. Airplanes 
with four or more engines must be able to make 20 deg.

[[Page 354]]

banked turns, with and against the inoperative engines, from steady 
flight at a speed equal to 1.3 VSR1, with maximum continuous 
power, and with the airplane in the configuration prescribed by 
paragraph (b) of this section.
    (e) Lateral control; all engines operating. With the engines 
operating, roll response must allow normal maneuvers (such as recovery 
from upsets produced by gusts and the initiation of evasive maneuvers). 
There must be enough excess lateral control in sideslips (up to sideslip 
angles that might be required in normal operation), to allow a limited 
amount of maneuvering and to correct for gusts. Lateral control must be 
enough at any speed up to VFC/MFC to provide a 
peak roll rate necessary for safety, without excessive control forces or 
travel.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-42, 
43 FR 2321, Jan. 16, 1978; Amdt. 25-72, 55 FR 29774, July 20, 1990; 
Amdt. 25-108, 67 FR 70827, Nov. 26, 2002]