Section 27.1509

14 CFR Ch. I (1-1-19 Edition)

(ii) Section 27.67 for multiengine helicopters.
(2) VNE (power-off) is - 
(i) A constant airspeed;
(ii) A constant amount less than
power-on VNE; or
(iii) A constant airspeed for a portion
of the altitude range for which certification is requested, and a constant
amount less than power-on VNE for the
remainder of the altitude range.
(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) 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]

Section 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. determined under Section 27.309(b); and
(2) The maximum r.p.m. shown during the type tests.
(b) Minimum power off. The minimum
power-off rotor speed must be established 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 design substantiation.
(c) Minimum power on. The minimum
power-on rotor speed must be established 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 design substantiation; and
(2) Not more than a value determined
under Section 27.33(a)(1) and (b)(1).

spaschal on DSK3GDR082PROD with CFR

Section 27.1519

Weight and center of gravity.

The weight and center of gravity limitations determined under SectionSection 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]

Section 27.1521

Powerplant limitations.

(a) General. The powerplant limitations 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 during 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 minutes, the maximum allowable cylinder
head, coolant outlet, or oil temperatures;
(5) The gas temperature limits for
turbine engines over the range of operating and atmospheric conditions for
which certification is requested.
(c) Continuous operation. The continuous 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 during the type tests;
(2) The minimum rotational speed
shown under the rotor speed requirements in Section 27.1509(c); and
(3) The gas temperature limits for
turbine engines over the range of operating and atmospheric conditions for
which certification is requested.
(d) Fuel grade or designation. The minimum fuel grade (for reciprocating engines), 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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