560
14 CFR Ch. I (1–1–24 Edition)
§ 27.1501
rotor failure will neither endanger the
occupants nor adversely affect contin-
ued safe flight.
[Amdt. 27–2, 33 FR 964, Jan. 26, 1968]
Subpart G—Operating Limitations
and Information
§ 27.1501
General.
(a) Each operating limitation speci-
fied in §§ 27.1503 through 27.1525 and
other limitations and information nec-
essary for safe operation must be es-
tablished.
(b) The operating limitations and
other information necessary for safe
operation must be made available to
the crewmembers as prescribed in
§§ 27.1541 through 27.1589.
(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral 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)))
[Amdt. 27–14, 43 FR 2325, Jan. 16, 1978]
O
PERATING
L
IMITATIONS
§ 27.1503
Airspeed limitations: general.
(a) An operating speed range must be
established.
(b) When airspeed limitations are a
function of weight, weight distribution,
altitude, rotor speed, power, or other
factors, airspeed limitations cor-
responding with the critical combina-
tions of these factors must be estab-
lished.
§ 27.1505
Never-exceed speed.
(a) The never-exceed speed, V
NE,
must
be established so that it is—
(1) Not less than 40 knots (CAS); and
(2) Not more than the lesser of—
(i) 0.9 times the maximum forward
speeds established under § 27.309;
(ii) 0.9 times the maximum speed
shown under §§ 27.251 and 27.629; or
(iii) 0.9 times the maximum speed
substantiated for advancing blade tip
mach number effects.
(b) V
NE
may vary with altitude,
r.p.m., temperature, and weight, if—
(1) No more than two of these vari-
ables (or no more than two instru-
ments integrating more than one of
these variables) are used at one time;
and
(2) The ranges of these variables (or
of the indications on instruments inte-
grating more than one of these vari-
ables) are large enough to allow an
operationally practical and safe vari-
ation of V
NE
.
(c) For helicopters, a stabilized
power-off V
NE
denoted as V
NE
(power-
off) may be established at a speed less
than V
NE
established pursuant to para-
graph (a) of this section, if the fol-
lowing conditions are met:
(1) V
NE
(power-off) is not less than a
speed midway between the power-on
V
NE
and the speed used in meeting the
requirements of—
(i) § 27.65(b) for single engine heli-
copters; and
(ii) § 27.67 for multiengine heli-
copters.
(2) V
NE
(power-off) is—
(i) A constant airspeed;
(ii) A constant amount less than
power-on V
NE
; or
(iii) A constant airspeed for a portion
of the altitude range for which certifi-
cation is requested, and a constant
amount less than power-on V
NE
for the
remainder of the altitude range.
(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral 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)))
[Amdt. 27–2, 33 FR 964, Jan. 26, 1968, and
Amdt. 27–14, 43 FR 2325, Jan. 16, 1978; Amdt.
27–21, 49 FR 44435, Nov. 6, 1984]
§ 27.1509
Rotor speed.
(a)
Maximum power-off (autorotation).
The maximum power-off rotor speed
must be established so that it does not
exceed 95 percent of the lesser of—
(1) The maximum design r.p.m. deter-
mined under § 27.309(b); and
(2) The maximum r.p.m. shown dur-
ing the type tests.
(b)
Minimum power off. The minimum
power-off rotor speed must be estab-
lished so that it is not less than 105
percent of the greater of—
(1) The minimum shown during the
type tests; and
(2) The minimum determined by de-
sign substantiation.
(c)
Minimum power on. The minimum
power-on rotor speed must be estab-
lished so that it is—
(1) Not less than the greater of—
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