(2)
Any di.erentials in tire diameters resulting from a combination of manufactu-ring tolerances, tiregrowth, and tire wear.A maximum tire-diameterdi.eren-tial equalto 2 ofthe most unfavorable combination ofdiameter variationsthat
3
is obtained when taking into account manufacturing tolerances, tire growth, and tire wear, may be assumed.
(3)
Any unequal tire in.ation pressure, assuming the maximum variation to be ±5 percent of the nominal tire in.ation pressure.
(4)
A runway crown of zero and a runway crown having a convex upward shape that may be approximated by a slope of 1 Demi percent with the horizontal. Runway crown e.ects must be considered with the nose gear unit on either slope of the crown.
(5)
The airplane attitude.
(6)
Any structural de.ections.
(c)
De.ated tires. The e.ect of de.ated tires on the structure must be considered with respecttotheloading conditions speci.edinparagraphs(d) through(f) ofthis section, taking into account the physical arrangement of the gear components. In addition–
(1)
The de.ation of any one tire for each multiple wheel landing gear unit, and the de.ation of any two critical tires for each landing gear unit using four or more wheels per unit, must be considered; and
(2)
The ground reactions must be applied to the wheels with in.ated tires except that,for multiple-wheelgearunits with morethan one shock strut, a rational distribution ofthegroundreactionsbetween thede.ated andin.ated tires, ac-countingforthedi.erencesin shock strutextensionsresultingfromade.ated tire, may be used.
(d)
Landing conditions.Foroneandfortwode.ated tires,the appliedload to eachgear unit is assumed to be 60 percent and 50 percent, respectively, of the limit load applied to each gear for each of the prescribed landing conditions. However, for thedriftlanding condition ofSec.25.485,100percent of the verticalload mustbe applied.
(e)
Taxiing and ground handling conditions. For one and for two de.ated tires–
(1)
The applied side or drag load factor, or both factors, at the center of gravity mustbethe most critical value up to50percent and40percent, respectively, of the limit side or drag load factors, or both factors, corresponding to the most severe condition resulting from consideration of the prescribed taxiing and ground handling conditions;
(2)
Forthebraked roll conditions ofSec.25.493(a) and(b)(2),thedrag loads on each in.ated tire may not be less than those at each tire for the symmetrical load distribution with no de.ated tires;
(3)
The vertical load factor at the center of gravity must be 60 percent and 50 percent, respectively, of the factor with no de.ated tires, except that it may not be less than 1g; and
(4) Pivoting need not be considered.
(f)
Towing conditions. For one and for two de.ated tires, the towing load, FTOW, must be60percent and50percent, respectively, oftheloadprescribed.
FAR25.519 :[Jacking and tie-downprovisions.]
(a)
[General. The airplane must be designed to withstand the limit load conditions resultingfrom the staticgroundload conditions ofparagraph(b) and,if applicable, paragraph(c) of this section at the most critical combinations of airplane weight and center ofgravity.The maximum allowablelimitload ateachjackpad mustbe speci.ed.
(b)
Jacking. The airplane must have provisions for jacking and must withstand the following limitloads whenthe airplaneis supported onjacks–
(1)
Forjacking by thelandinggear atthe maximum ramp weight of the airplane, the airplane structure must be designed for a vertical load of 1.33 times the vertical static reactionat eachjackingpoint acting singly andin combination with a horizontal load 0.33 times the vertical static reaction applied in any direction.
(2)
Forjackingby other airplane structure at maximum approvedjacking weight :
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 3(61)
