---
kind: "section"
citation: "14 C.F.R. § 27.175"
title: "14"
number: "27.175"
heading: "Demonstration of static longitudinal stability."
url: "https://uscodex.org/cfr/14/27.175"
---

# §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 VY.
- (b) **Cruise.** Static longitudinal stability must be shown in the cruise condition at speeds from 0.8 VNE − 10 kt to 0.8 VNE + 10 kt or, if VH is less than 0.8 VNE, from VH −10 kt to VH + 10 kt, with—
  - (1) Critical weight;
  - (2) Critical center of gravity;
  - (3) Power for level flight at 0.8 VNE or VH, whichever is less;
  - (4) The landing gear retracted; and
  - (5) The rotorcraft trimmed at 0.8 VNE or VH, whichever is less.
- (c) **V—** NE. Static longitudinal stability must be shown at speeds from VNE − 20 kt to VNE with—
  - (1) Critical weight;
  - (2) Critical center of gravity;
  - (3) Power required for level flight at VNE −10 kt or maximum continuous power, whichever is less;
  - (4) The landing gear retracted; and
  - (5) **The rotorcraft trimmed at V<I>NE</I> − 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.**

## Notes

### Amendments

[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]

### Authority

Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704.

### Source

Source: Docket No. 5074, 29 FR 15695, Nov. 24, 1964, unless otherwise noted.

### Amendments

[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]