Text in force at CS27-10: from CS27-10, effective 8 Feb 2023.
(a) Each airspeed indicator must be marked as specified in sub-paragraph (b), with the marks located at the corresponding indicated airspeeds.
(b) The following markings must be made:
(1) A red radial line:
(i) For rotorcraft other than helicopters, at VNE; and
(ii) For helicopters at VNE (power-on).
(2) A red cross-hatched radial line at VNE (power-off) for helicopters, if VNE (power-off) is less than VNE (power-on).
(3) For the caution range, a yellow range arc.
(4) For the safe operating range, a green or unmarked range arc.
ED Decision 2023/001/R · Source