(b)
Engine or drive system cooling fan blade protection.

(1) If anengineorrotordrivesystemcoolingfanisinstalled,theremustbe means toprotect the rotorcraft and allow a safelandingif afanbladefails.This must be shown by showing that–
(i)
The fan blades are contained in case of failure;

(ii)
Eachfanislocated sothat afailure will notjeopardize safety; or

(iii) Eachfanblade can withstandan ultimateload of1.5timesthe centrifugal force resulting from operation limited by the following :
(A) For fans driven directly by the engine–
(1) Theterminal engine r.p.m. under uncontrolled conditions; or
′
Elodie Roux. Septembre 2003
Subpart E : Powerplant
(2) An overspeed limiting device.
(B) For fans driven by the rotor drive system, the maximum rotor drive system rotational speedtobe expectedin service,includingtransients.
(2) Unless a fatigue evaluation under Sec. 27.571 is conducted, it must be shown that cooling fan blades are not operating at resonant conditions within the operating limits of the rotorcraft.]
(c) Turbine engine installation. For turbine engineinstallations, thepowerplant systems associated with engine control devices, systems, and instrumentation must be de-signed to give reasonable assurance that those engine operating limitations that adversely a.ect turbine rotor structural integrity will not be exceeded in service.
Amdt. 27-23, E.. 10/3/88
FAR 27.907 : Engine vibration
(a)
Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft.

(b)
The addition of the rotor and the rotor drive system to the engine may not subject theprincipal rotatingpartsof the engineto excessivevibrationstresses.This must be shown by a vibration investigation.

(c)
No part of the rotor drive system may be subjected to excessive vibration stresses.

65.2 Rotor Drive System
FAR 27.917 : Design
(a)
Each rotor drive system must incorporate a unit for each engine to automatically disengage that engine from the main and auxiliary rotors if that engine fails.

(b)
Each rotor drive system must be arranged so that each rotor necessary for control in autorotation will continue to be driven by the main rotors after disengagement of the engine from the main and auxiliary rotors.

(c)
If atorquelimiting deviceis usedinthe rotordrive system,it mustbelocated so as to allow continued control of the rotorcraft when the device is operating.

(d)
[The rotor drive system includes any part necessary to transmit power from the enginestothe rotorhubs.Thisincludesgearboxes, shafting, universaljoints, cou-plings, rotor brake assemblies, clutches, supporting bearings for shafting, any at-tendant accessorypads ordrives, and any cooling fansthat are apart of, attached to, or mounted on the rotor drive system.]

Amdt. 27-11, E.. 2/1/77
FAR 27.921 : Rotor brake
If there is a means to control the rotation of the rotor drive system independently of the engine, any limitations on the use of that means must be speci.ed, and the control for that means must be guarded to prevent inadvertent operation.
FAR 27.923 : Rotor drive system and control mechanism tests
(a)
Each part tested as prescribed in this section must be in a serviceable condition at the end of the tests.Nointerveningdisassembly which might a.ect test results may be conducted.

(b)
Each rotor drive system and control mechanism must be tested for not less than 100 hours. The test must be conducted on the rotorcraft, and the torque must be absorbed by the rotors to be installed, except that other ground or .ight test facilities with other appropriate methods of torque absorption may be used if the conditions of support and vibration closely simulate the conditions that would exist during a test on the rotorcraft.
　
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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(103)