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14 CFR Ch. I (1–1–19 Edition)

§ 27.1509

(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—
(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:

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