---
kind: "section"
citation: "14 C.F.R. § 27.1509"
title: "14"
number: "27.1509"
heading: "Rotor speed."
url: "https://uscodex.org/cfr/14/27.1509"
---

# §27.1509. Rotor speed.

- (a) **Maximum power-off (autorotation).** The maximum power-off rotor speed must be established so that it does not exceed 95 percent of the lesser of—
  - (1) The maximum design r.p.m. determined under [§ 27.309(b)](/cfr/14/27.309.md?p=b); and
  - (2) The maximum r.p.m. shown during the type tests.
- (b) **Minimum power off.** The minimum power-off rotor speed must be established so that it is not less than 105 percent of the greater of—
  - (1) The minimum shown during the type tests; and
  - (2) **The minimum determined by design substantiation.**
- (c) **Minimum power on.** The minimum power-on rotor speed must be established so that it is—
  - (1) **Not less than the greater of—**
    - (i) The minimum shown during the type tests; and
    - (ii) The minimum determined by design substantiation; and
  - (2) Not more than a value determined under § [27.33(a)(1)](/cfr/14/27.33.md?p=a-1) and [(b)(1)](/cfr/14/27.33.md?p=b-1).

## Notes

### 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.