Title 14: Aeronautics and Space
PART 23—AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES
Subpart G—Operating Limitations and Information
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§ 23.1505 Airspeed limitations.
(a) The never-exceed speed VNE must be established so that it is—
(1) Not less than 0.9 times the minimum value of VD allowed under §23.335; and
(2) Not more than the lesser of—
(i) 0.9 VD established under §23.335; or
(ii) 0.9 times the maximum speed shown under §23.251.
(b) The maximum structural cruising speed VNO must be established so that it is—
(1) Not less than the minimum value of VC allowed under §23.335; and
(2) Not more than the lesser of—
(i) VC established under §23.335; or
(ii) 0.89 VNE established under paragraph (a) of this section.
(c) Paragraphs (a) and (b) of this section do not apply to turbine airplanes or to airplanes for which a design diving speed VD/MD is established under §23.335(b)(4). For those airplanes, a maximum operating limit speed (VMO/MMO-airspeed or Mach number, whichever is critical at a particular altitude) must be established as a speed that may not be deliberately exceeded in any regime of flight (climb, cruise, or descent) unless a higher speed is authorized for flight test or pilot training operations. VMO/MMO must be established so that it is not greater than the design cruising speed VC/MC and so that it is sufficiently below VD/MD and the maximum speed shown under §23.251 to make it highly improbable that the latter speeds will be inadvertently exceeded in operations. The speed margin between VMO/MMO and VD/MD or the maximum speed shown under §23.251 may not be less than the speed margin established between VC/MC and VD/MD under §23.335(b), or the speed margin found necessary in the flight test conducted under §23.253.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23–7, 34 FR 13096, Aug. 13, 1969]
