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Federal Aviation Regulations

Sec. 23.1545 — Airspeed indicator.

(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) For the never-exceed speed V NE,a radial red line.

(2) For the caution range, a yellow arc extending from the red line specified in paragraph (b)(1) of this section to the upper limit of the green arc specified in paragraph (b)(3) of this section.

(3) For the normal operating range, a green arc with the lower limit at V S1with maximum weight and with landing gear and wing flaps retracted, and the upper limit at the maximum structural cruising speed V NOestablished under §23.1505(b).

(4) For the flap operating range, a white arc with the lower limit at V S0at the maximum weight, and the upper limit at the flaps-extended speed V FEestablished under §23.1511.

(5) For reciprocating multiengine-powered airplanes of 6,000 pounds or less maximum weight, for the speed at which compliance has been shown with §23.69(b) relating to rate of climb at maximum weight and at sea level, a blue radial line.

(6) For reciprocating multiengine-powered airplanes of 6,000 pounds or less maximum weight, for the maximum value of minimum control speed, VMC, (one-engine-inoperative) determined under §23.149(b), a red radial line.

(c) If V NEor V NOvary with altitude, there must be means to indicate to the pilot the appropriate limitations throughout the operating altitude range.

(d) Paragraphs (b)(1) through (b)(3) and paragraph (c) of this section do not apply to aircraft for which a maximum operating speed V MO/ M MOis established under §23.1505(c). For those aircraft there must either be a maximum allowable airspeed indication showing the variation of V MO/ M MOwith altitude or compressibility limitations (as appropriate), or a radial red line marking for V MO/ M MOmust be made at lowest value of V MO/ M MOestablished for any altitude up to the maximum operating altitude for the airplane.

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23–3, 30 FR 14240, Nov. 13, 1965; Amdt. 23–7, 34 FR 13097, Aug. 13, 1969; Amdt. 23–23, 43 FR 50593, Oct. 30, 1978; Amdt. 23–50, 61 FR 5193, Feb. 9, 1996]

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