(1) The lateral displacement of the c.g. results from random passenger or cargo disposition within the fuselage or from random unsymmetrical fuel loading or fuel usage; and
(2) Appropriateloadinginstructionsforrandomdisposableloadsareincluded un-der theprovisions ofSec.25.1583(c)(1)to ensure that thelateraldisplacement of the center of gravity is maintained within these limits.
(c) Landing gear dimension data. Figure 1 of Appendix A contains the basic landing gear dimension data.]
Amdt. 25-23, E.. 5/8/70
FAR 25.473 : Landing load conditions and assumptions.
(a)
For the landing conditions speci.ed in Sec. 25.479 to Sec. 25.485 the airplane is assumed to contact the ground–

(1)
In the attitudes de.ned in Sec. 25.479 and Sec. 25.481;

(2)
With alimitdescent velocity of10fps atthedesignlanding weight(the maxi-mum weight for landing conditions at maximum descent velocity); and

(3)
With alimitdescent velocity of6fps atthedesigntake-o. weight(the maxi-mum weight for landing conditions at a reduced descent velocity).

(4)
The prescribed descent velocities may be modi.ed if it is shown that the air-plane has design features that make it impossible to develop these velocities.

(b)
Airplane lift, not exceeding airplane weight, may be assumed unless the presence of systems or procedures signi.cantly a.ects the lift.

(c)
The method of analysis of airplane and landing gear loads must take into account at least the following elements :

(1)
Landing gear dynamic characteristics.

(2)
Spin-up and springback.

(3)
Rigid body response.

(4)
Structural dynamic response of the airframe, if signi.cant.

(d)
[The landing gear dynamic characteristics must be validated bytests as de.ned in Sec. 25.723(a).]

(e)
The coe.cient of friction between the tires and the ground may be established by considering the e.ects of skidding velocity and tire pressure. However, this coe.cient of friction need not be more than 0.8.

Amdt. 25-103, E.. 6/15/2001
FAR 25.477 : Landing gear arrangement.
Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nosegears, or main and tailgears, when normal operating techniques are used.
FAR 25.479 : Level landing conditions.
(a) [In the level attitude, the airplane is assumed to contact the ground at forward velocity components, ranging from VL1 to 1.25 VL2 parallel to the ground under the conditions prescribed in Sec. 25.473 with–
(1) VL1 equal to VS0 (TAS)attheappropriatelanding weight andinstandard sea level conditions; and
′
Elodie Roux. Septembre 2003
Subpart C : Structure
(2)
VL2 equal to VS0 (TAS)at the appropriate landing weight and altitudes in a hot day temperature of 41 degrees F. above standard.

(3)
The e.ects ofincreasedcontact speed mustbeinvestigatedif approval ofdown-wind landings exceeding 10 knots is requested.

(b)
For the level landing attitude for airplanes with tail wheels, the conditions speci.ed in this section must be investigated with the airplane horizontal reference line horizontal in accordance with Figure 2 of Appendix A of this part.

(c)
For the level landing attitude for airplanes with nose wheels, shown in Figure 2 of AppendixAofthispart,the conditions speci.edinthis section mustbeinvestigated assuming the following attitudes :

(1)
An attitudein which the mainwheels areassumed to contacttheground with the nose wheeljust clear of theground; and

(2)
If reasonably attainable at the speci.ed descent and forward velocities, an attitudein which the nose and main wheels are assumed to contact theground simultaneously.

(d)
In additiontotheloading conditionsprescribedinparagraph(a) ofthis section, but with maximum verticalground reactions calculatedfromparagraph(a),the following apply :
　
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