14 C.F.R. § 27.1545 Airspeed indicator.
Title 14 - Aeronautics and Space
(a) Each airspeed indicator must be marked as specified in paragraph (b) of this section, with the marks located at the corresponding indicated airspeeds. (b) The following markings must be made: (1) A red radial line— (i) For rotocraft other than helicopters, at V (ii) For helicopters at V (2) A red cross-hatched radial line at V (3) For the caution range, a yellow arc. (4) For the safe operating range, a green arc. (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))) [Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27–14, 43 FR 2325, Jan. 16, 1978; 43 FR 3900, Jan. 30, 1978; Amdt. 27–16, 43 FR 50599, Oct. 30, 1978]
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart G—Operating Limitations and Information
Markings and Placards
§ 27.1545 Airspeed indicator.