[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR27.175]

[Page 566-567]
 
                     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 567]]

    (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]