§27.175 Demonstration of static longitudinal stability.

(a) Climb. Static longitudinal stability must be shown in the climb condition at speeds from V_Y -10 kt to V_Y +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)))

[Docket 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]