The following are required flight and navigational instruments:
(a) An airspeed indicator. For Category A rotorcraft with VNE
less than a speed at which unmistakable pilot cues provide overspeed
warning, a maximum allowable airspeed indicator must be provided. If
maximum allowable airspeed varies with weight, altitude, temperature, or
r.p.m., the indicator must show that variation.
(b) A sensitive altimeter.
(c) A magnetic direction indicator.
(d) A clock displaying hours, minutes, and seconds with a sweep-second
pointer or digital presentation.
(e) A free-air temperature indicator.
(f) A non-tumbling gyroscopic bank and pitch indicator.
(g) A gyroscopic rate-of-turn indicator combined with an integral
slip-skid indicator (turn-and-bank indicator) except that only a slip-skid
indicator is required on rotorcraft with a third altitude instrument
system that --
(1) Is useable through flight altitudes of ± 80 degrees of pitch and ±
120 degrees of roll;
(2) Is powered from a source independent of the electrical generating
(3) Continues reliable operation for a minimum of 30 minutes after
total failure of the electrical generating system;
(4) Operates independently of any other altitude indicating system;
(5) Is operative without selection after total failure of the
electrical generating system;
(6) Is located on the instrument panel in a position acceptable to the
Administrator that will make it plainly visible to and useable by any
pilot at his station; and
(7) Is appropriately lighted during all phases of operation.
(h) A gyroscopic direction indicator.
(i) A rate-of-climb (vertical speed) indicator.
(j) For Category A rotorcraft, a speed warning device when VNE
is less than the speed at which unmistakable overspeed warning is provided
by other pilot cues. The speed warning device must give effective aural
warning (differing distinctively from aural warnings used for other
purposes) to the pilots whenever the indicated speed exceeds VNE
plus 3 knots and must operate satisfactorily throughout the approved range
of altitudes and temperatures. (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), Dept. of Transportation Act (49 U.S.C.