(b)
Acceptance Criteria.The speci.c optical smokedensity(DS), which is obtained by averaging the reading obtained after 4 minutes with each of the three specimens, shall not exceed 200.]
Amdt. 25-66, E.. 9/26/88
′
Elodie Roux. Septembre 2003
Appendix F
Chapitre 57 Appendix G
FAR25.G1 :[AppendixG–ContinuousGustDesignCriteria]
[The continuousgustdesign criteriain this appendix mustbe usedin establishingthe dynamic response of the airplane to vertical and lateral continuous turbulences unless a more rational criteria is used. The following gust load requirements apply to mission analysis and design envelope analysis :
(a)
Thelimitgustloads utilizing the continuous turbulence concept mustbedetermined in accordancewiththeprovisionsof eitherparagraph(b) orparagraphs(c) and (d)of this appendix.
(b)
Design envelope analysis. The limit loads must be determined in accordance with the following :
(1)
All critical altitudes, weights, and weight distributions, as speci.ed in Sec. 25.321(b), and all critical speeds within the ranges indicated in paragraph (b)(3)of this appendix must be considered.
(2)
Values of Aˉ(ratio ofroot-mean-squareincrementalload root-mean-squaregust velocity) mustbedeterminedbydynamic analysis.Thepower spectraldensity of the atmospheric turbulence must be as given by the equation–
σ2 L 8
2
1+ (1.339LΩ)
3
.(Ω) =
()11
π
6
2
1+(1.339LΩ)
where :
. : power-spectral density (ft./sec.)2/rad./ft.
σ : root-mean-squaregust velocity, ft./sec.
Ω : reduced frequency, rad/ft.
L =2,500ft. :
(3) The limit loads must be obtained by multiplying the Aˉvalues determined by the dynamic analysis by the following values of the gust velocity Uσ :
(i) At speed VC : Uσ =85fps truegust velocityin the interval0 to 30,000ft. altitude andislinearlydecreased to30fpstruegustvelocity at80,000ft. altitude. Where the Administrator .nds that a design is comparable to a similar design with extensive satisfactory service experience, it will be acceptableto select Uσ at VC lessthan85fps,butnotlessthan75fps, with
759
Appendix G
lineardecreasefrom that value at 20,000feet to 30fps at80,000feet. The following factors will be taken into account when assessing comparability to a similar design :
(1)
Thetransferfunction ofthe newdesign shouldexhibit no unusual cha-racteristics as compared to the similar design which will signi.cantly a.ect response to turbulence; e.g., coalescence of modal responsein thefrequency regime which can resultin a signi.cantincrease ofloads.
(2)
The typical mission of the new airplane is substantially equivalent to that of the similar design.
(3)
The similar design should demonstrate the adequacy of the Uσ selec-ted.
(ii) At speed VB : Uσ is equal to 1.32 times the values obtained under para-graph(b)(3)(i) of this appendix.
(iii) At speed VD : Uσ is equal to 1 the values obtained under paragraph
2
(b)(3)(i)of this appendix.
(iv) At speeds between VB and VC and between VC and VD : Uσ is equal to a value obtained by linear interpolation.
(4) When a stability augmentation system is included in the analysis, the e.ect of system nonlinearities on loads at the limit load level must be realistically or conservatively accounted for.
(c) Mission analysis. Limit loads must be determined in accordance with the following :
(1)
The expected utilization of the airplane must be represented by one or more .ight pro.les in which the load distribution and the variation with time of speed, altitude,gross weight, and center ofgravityposition arede.ned. These pro.les mustbedividedinto mission segments orblocks,for analysis, andave-rage or e.ective values of the pertinent parameters de.ned for each segment.
中國航空網 m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：FAA規章 美國聯邦航空規章 Federal Aviation Regulations 4(58)
