title-14-part-27-sec27-1509

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]

PERATING

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

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

power-off V

denoted as V

(power-

off) may be established at a speed less
than V

established pursuant to para-

graph (a) of this section, if the fol-
lowing conditions are met:

(1) V

(power-off) is not less than a

speed midway between the power-on
V

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

(power-off) is—

(i) A constant airspeed;
(ii) A constant amount less than

power-on V

; 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

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—

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00570

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR

561

Federal Aviation Administration, DOT

§ 27.1521

(i) The minimum shown during the

type tests; and

(ii) The minimum determined by de-

sign substantiation; and

(2) Not more than a value determined

under § 27.33(a)(1) and (b)(1).

§ 27.1519

Weight and center of gravity.

The weight and center of gravity lim-

itations determined under §§ 27.25 and
27.27, respectively, must be established
as operating limitations.

[Amdt. 27–2, 33 FR 965, Jan. 26, 1968, as
amended by Amdt. 27–21, 49 FR 44435, Nov. 6,
1984]

§ 27.1521

Powerplant limitations.

(a)

General. The powerplant limita-

tions prescribed in this section must be
established so that they do not exceed
the corresponding limits for which the
engines are type certificated.

(b)

Takeoff operation. The powerplant

takeoff operation must be limited by—

(1) The maximum rotational speed,

which may not be greater than—

(i) The maximum value determined

by the rotor design; or

(ii) The maximum value shown dur-

ing the type tests;

(2) The maximum allowable manifold

pressure (for reciprocating engines);

(3) The time limit for the use of the

power corresponding to the limitations
established in paragraphs (b)(1) and (2)
of this section;

(4) If the time limit in paragraph

(b)(3) of this section exceeds two min-
utes, the maximum allowable cylinder
head, coolant outlet, or oil tempera-
tures;

(5) The gas temperature limits for

turbine engines over the range of oper-
ating and atmospheric conditions for
which certification is requested.

(c)

Continuous operation. The contin-

uous operation must be limited by—

(1) The maximum rotational speed

which may not be greater than—

(i) The maximum value determined

by the rotor design; or

(ii) The maximum value shown dur-

ing the type tests;

(2) The minimum rotational speed

shown under the rotor speed require-
ments in § 27.1509(c); and

(3) The gas temperature limits for

turbine engines over the range of oper-

ating and atmospheric conditions for
which certification is requested.

(d)

Fuel grade or designation. The min-

imum fuel grade (for reciprocating en-
gines), or fuel designation (for turbine
engines), must be established so that it
is not less than that required for the
operation of the engines within the
limitations in paragraphs (b) and (c) of
this section.

(e)

Turboshaft engine torque. For

rotorcraft with main rotors driven by
turboshaft engines, and that do not
have a torque limiting device in the
transmission system, the following
apply:

(1) A limit engine torque must be es-

tablished if the maximum torque that
the engine can exert is greater than—

(i) The torque that the rotor drive

system is designed to transmit; or

(ii) The torque that the main rotor

assembly is designed to withstand in
showing compliance with § 27.547(e).

(2) The limit engine torque estab-

lished under paragraph (e)(1) of this
section may not exceed either torque
specified in paragraph (e)(1)(i) or (ii) of
this section.

(f)

Ambient temperature. For turbine

engines, ambient temperature limita-
tions (including limitations for winter-
ization installations, if applicable)
must be established as the maximum
ambient atmospheric temperature at
which compliance with the cooling pro-
visions of §§ 27.1041 through 27.1045 is
shown.

(g)

Two and one-half-minute OEI power

operation. Unless otherwise authorized,
the use of 2

⁄

-minute OEI power must

be limited to engine failure operation
of multiengine, turbine-powered rotor-
craft for not longer than 2

⁄

minutes

after failure of an engine. The use of
2

⁄

-minute OEI power must also be lim-

ited by—

(1) The maximum rotational speed,

which may not be greater than—

(i) The maximum value determined

by the rotor design; or

(ii) The maximum demonstrated dur-

ing the type tests;

(2) The maximum allowable gas tem-

perature; and

(3) The maximum allowable torque.
(h)

Thirty-minute OEI power operation.

Unless otherwise authorized, the use of
30-minute OEI power must be limited

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00571

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR