(iii) 0.9timesthe maximum speedsubstantiatedfor advancingbladetip mach number e.ects.]

(b)
VNE may vary with altitude, r.p.m., temperature, and weight, if–

(1)
No morethantwo ofthe variables(or no morethantwoinstrumentsintegrating morethan one ofthese variables) are used at onetime; and

(2)
The rangesof these variables(or of theindications oninstrumentsintegrating more than one of these variables) are large enough to allow an operationally practical and safe variation of VNE.

(c)
For helicopters, a stabilized power-o. VNE denoted as VNE (power-o.) may be established at a speed less than VNE establishedpursuanttoparagraph(a) of this section, if the following conditions are met :

(1)
VNE (power-o.)is not less than a speed midway between the power-on VNE and the speed used in meeting the requirements of–

(i)
Sec. 27.65(b) for single engine helicopters; and

(ii)
Sec. 27.67 for multiengine helicopters.

(2)
VNE (power-o.)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 certi-.cation is requested, and a constant amount less than power-on VNE for the remainder of the altitude range.
Amdt. 27-21, E.. 12/6/84
FAR 27.1509 : Rotor speed
(a)
Maximum power-o. (autorotation). The maximum power-o. 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 Sec. 27.309(b); and

(2)
The maximum r.p.m. shown during the type tests.

(b)
Minimum power o.. The minimum power-o. rotor speed must be established so thatitis notlessthan105percent of thegreater of–

(1)
The minimum shownduring thetypetests; and

(2)
The minimum determined by design substantiation.

(c)
Minimumpower on.The minimumpower-on rotor speed mustbe established so that it is–

(1)
Not less than the greater of–

(i)
The minimum shownduring thetypetests; and

(ii)
The minimum determined by design substantiation; and

(2)
Not morethan a valuedetermined underSec.27.33(a)(1) and(b)(1).

FAR 27.1519 : Weight and center of gravity
[The weightand center ofgravitylimitationsdetermined underSecs.27.25 and27.27, respectively, must be established as operating limitations.] Amdt. 27-21, E.. 12/6/84
FAR 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 certi.cated.

(b)
Takeo. operation. The powerplant takeo. operation must be limited by–

(1)
The maximum rotational speed, which may not be greater than–

(i)
The maximum valuedeterminedby the rotordesign; or

(ii)
The maximum value shown during the type tests;

(2)
The maximum allowable manifoldpressure(for reciprocating engines);

(3)
The time limit for the use of the power corresponding to the limitations esta-blishedinparagraphs(b)(1) and(2) of this section;

(4)
If the timelimitinparagraph(b)(3) ofthis section exceedstwo minutes, the maximum allowable cylinder head, coolant outlet, or oil temperatures;

(5)
Thegas temperaturelimitsfor turbine engines over the range of operating and atmospheric conditions for which certi.cation is requested.

(c)
Continuous operation. The continuous operation must be limited by–

(1)
The maximum rotational speed, which may not be greater than–
　
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本文鏈接地址：FAA規(guī)章 美國聯(lián)邦航空規(guī)章 Federal Aviation Regulations 4(133)