[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: 14CFR27.175]



[Page 575-576]

 

                     TITLE 14--AERONAUTICS AND SPACE

 

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

 

PART 27_AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT--Table 

of Contents

 

                            Subpart B_Flight

 

Sec. 27.175  Demonstration of static longitudinal stability.



    (a) Climb. Static longitudinal stability must be shown in the climb 

condition at speeds from 0.85 VY to 1.2 VY, with--

    (1) Critical weight;

    (2) Critical center of gravity;

    (3) Maximum continuous power;

    (4) The landing gear retracted; and

    (5) The rotorcraft trimmed at VY.

    (b) Cruise. Static longitudinal stability must be shown in the 

cruise condition at speeds from 0.7 VH or 0.7 VNE, whichever is less, to 

1.1 VH or 1.1 VNE, whichever is less, with--



[[Page 576]]



    (1) Critical weight;

    (2) Critical center of gravity;

    (3) Power for level flight at 0.9 VH or 0.9 VNE, whichever is less;

    (4) The landing gear retracted; and

    (5) The rotorcraft trimmed at 0.9 VH or 0.9 VNE, whichever is less.

    (c) Autorotation. Static longitudinal stability must be shown in 

autorotation at airspeeds from 0.5 times the speed for minimum rate of 

descent to VNE, or to 1.1 VNE (power-off) if VNE (power-off) is 

established under Sec. 27.1505(c), and with--

    (1) Critical weight;

    (2) Critical center of gravity;

    (3) Power off;

    (4) The landing gear--

    (i) Retracted; and

    (ii) Extended; and

    (5) The rotorcraft trimmed at appropriate speeds found necessary by 

the Administrator to demonstrate stability throughout the prescribed 

speed range.

    (d) Hovering. For helicopters, the longitudinal cyclic control must 

operate with the sense and direction of motion prescribed in Sec. 

27.173 between the maximum approved rearward speed and a forward speed 

of 17 knots with--

    (1) Critical weight;

    (2) Critical center of gravity;

    (3) Power required to maintain an approximate constant height in 

ground effect;

    (4) The landing gear extended; and

    (5) The helicopter trimmed for hovering.



(Secs. 313(a), 601, 603, 604, and 605 of the Federal Aviation Act of 

1958 (49 U.S.C. 1354(a), 1421, 1423, 1424, and 1425); and sec. 6(c) of 

the Dept. of Transportation Act (49 U.S.C. 1655(c)))



[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27-2, 33 

FR 963, Jan. 26, 1968; Amdt. 27-11, 41 FR 55468, Dec. 20, 1976; Amdt. 

27-14, 43 FR 2325, Jan. 16, 1978; Amdt. 27-21, 49 FR 44433, Nov. 6, 

1984; Amdt. 27-34, 62 FR 46173, Aug. 29, 1997]