14 C.F.R. § 27.1505 Never-exceed speed.
Title 14 - Aeronautics and Space
(a) The never-exceed speed, V (1) Not less than 40 knots (CAS); and (2) Not more than the lesser of— (i) 0.9 times the maximum forward speeds established under §27.309; (ii) 0.9 times the maximum speed shown under §§27.251 and 27.629; or (iii) 0.9 times the maximum speed substantiated for advancing blade tip mach number effects. (b) V (1) No more than two of these variables (or no more than two instruments integrating more than one of these variables) are used at one time; and (2) The ranges of these variables (or of the indications on instruments integrating more than one of these variables) are large enough to allow an operationally practical and safe variation of V (c) For helicopters, a stabilized power-off V (1) V (i) §27.65(b) for single engine helicopters; and (ii) §27.67 for multiengine helicopters. (2) V (i) A constant airspeed; (ii) A constant amount less than power-on V (iii) A constant airspeed for a portion of the altitude range for which certification is requested, and a constant amount less than power-on V (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))) [Amdt. 27–2, 33 FR 964, Jan. 26, 1968, and Amdt. 27–14, 43 FR 2325, Jan. 16, 1978; Amdt. 27–21, 49 FR 44435, Nov. 6, 1984]
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart G—Operating Limitations and Information
Operating Limitations
§ 27.1505 Never-exceed speed.