Title 14 - Aeronautics and Space
Volume: 1Date: 2023-01-01Original Date: 2023-01-01Title: Section 27.175 - Demonstration of static longitudinal stability.Context:
Title 14 - Aeronautics and Space. CHAPTER I - FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION. SUBCHAPTER C - AIRCRAFT. PART 27 - AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT. Subpart B - Flight. - Flight Characteristics.
§ 27.175
Demonstration of static longitudinal stability.
(a)
Climb.
Static longitudinal stability must be shown in the climb condition at speeds from Vy − 10 kt to Vy + 10 kt with—
(1) Critical weight;
(2) Critical center of gravity;
(3) Maximum continuous power;
(4) The landing gear retracted; and
(5) The rotorcraft trimmed at
V
Y.
(b)
Cruise.
Static longitudinal stability must be shown in the cruise condition at speeds from 0.8 V
NE
− 10 kt to 0.8 V
NE
+ 10 kt or, if V
H
is less than 0.8 V
NE
, from V
H
−10 kt to V
H
+ 10 kt, with—
(1) Critical weight;
(2) Critical center of gravity;
(3) Power for level flight at 0.8 V
NE
or V
H
, whichever is less;
(4) The landing gear retracted; and
(5) The rotorcraft trimmed at 0.8 V
NE
or V
H
, whichever is less.
(c)
V
NE.
Static longitudinal stability must be shown at speeds from V
NE
− 20 kt to V
NE
with—
(1) Critical weight;
(2) Critical center of gravity;
(3) Power required for level flight at V
NE
−10 kt or maximum continuous power, whichever is less;
(4) The landing gear retracted; and
(5) The rotorcraft trimmed at V
NE
− 10 kt.
(d)
Autorotation.
Static longitudinal stability must be shown in autorotation at—
(1) Airspeeds from the minimum rate of descent airspeed−10 kt to the minimum rate of descent airspeed + 10 kt, with—
(i) Critical weight;
(ii) Critical center of gravity;
(iii) The landing gear extended; and
(iv) The rotorcraft trimmed at the minimum rate of descent airspeed.
(2) Airspeeds from best angle-of-glide airspeed−10 kt to the best angle-of-glide airspeed + 10 kt, with—
(i) Critical weight;
(ii) Critical center of gravity;
(iii) The landing gear retracted; and
(iv) The rotorcraft trimmed at the best angle-of-glide airspeed.
(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; Amdt. 27–44, 73 FR 10999, Feb. 29, 2008]