[Code of Federal Regulations]

[Title 14, Volume 1]

[Revised as of January 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 14CFR25.147]



[Page 359-360]

 

                     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; roll capability. With the critical engine 

inoperative, roll response must allow normal maneuvers. Lateral control 

must be sufficient, at



[[Page 360]]



the speeds likely to be used with one engine inoperative, to provide a 

roll rate necessary for safety without excessive control forces or 

travel.

    (e) Lateral control; airplanes with four or more engines. Airplanes 

with four or more engines must be able to make 20[deg] 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.

    (f) 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; Amdt. 25-115, 69 FR 40527, 

July 2, 2004]