[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: 14CFR23.175]



[Page 197-198]

 

                     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. 23.175  Demonstration of static longitudinal stability.



    Static longitudinal stability must be shown as follows:

    (a) Climb. The stick force curve must have a stable slope at speeds 

between 85 and 115 percent of the trim speed, with--

    (1) Flaps retracted;

    (2) Landing gear retracted;

    (3) Maximum continuous power; and

    (4) The airplane trimmed at the speed used in determining the climb 

performance required by Sec. 23.69(a).

    (b) Cruise. With flaps and landing gear retracted and the airplane 

in trim with power for level flight at representative cruising speeds at 

high and low altitudes, including speeds up to VNO or 

VMO/MMO, as appropriate, except that the speed 

need not exceed VH--

    (1) For normal, utility, and acrobatic category airplanes, the stick 

force curve must have a stable slope at all speeds within a range that 

is the greater of 15 percent of the trim speed plus the resulting free 

return speed range, or 40 knots plus the resulting free return speed 

range, above and below the trim speed, except that the slope need not be 

stable--

    (i) At speeds less than 1.3 VS1; or

    (ii) For airplanes with VNE established under Sec. 

23.1505(a), at speeds greater than VNE; or

    (iii) For airplanes with VMO/MMO established 

under Sec. 23.1505(c), at speeds greater than VFC/

MFC.

    (2) For commuter category airplanes, the stick force curve must have 

a stable slope at all speeds within a range of 50 knots plus the 

resulting free return speed range, above and below the trim speed, 

except that the slope need not be stable--

    (i) At speeds less than 1.4 VS1; or

    (ii) At speeds greater than VFC/MFC; or

    (iii) At speeds that require a stick force greater than 50 pounds.

    (c) Landing. The stick force curve must have a stable slope at 

speeds between 1.1 VS1 and 1.8 VS1 with--



[[Page 198]]



    (1) Flaps in the landing position;

    (2) Landing gear extended; and

    (3) The airplane trimmed at--

    (i) VREF, or the minimum trim speed if higher, with power 

off; and

    (ii) VREF with enough power to maintain a 3 degree angle 

of descent.



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