(b)
For airplanes with nose wheels, thepitching moment mustbebalancedby rotational inertia.

(c)
For airplanes with tail wheels, the resultant of the ground reactions must pass through the center ofgravity of the airplane.

FAR 25.509 : Towing loads.

(a)
The towingloads speci.edinparagraph(d) of this section mustbe considered se-parately. These loads must be applied at the towing .ttings and must act parallel to the ground. In addition–

(1) A vertical load factor equal to 1.0 must be considered acting at the center of gravity;
(2)
The shock struts andtires mustbeintheir staticpositions; and

(3)
With WT asthe[design ramp weight],thetowing load, FTOW, is–

(i) 0.3 WT for WT less than 30,000pounds;
(ii) 6WT +450000
for WT between30,000 and100,000pounds; and
70
(iii) 0.15 WT for WT over 100,000pounds.
(b)
For towing points not on the landing gear but near the plane of symmetry of the airplane, the drag and side tow load components speci.ed for the auxiliary gear apply.Fortowingpointslocated outboard of the maingear,thedrag and sidetow load components speci.ed for the main gear apply. Where the speci.ed angle of swivel cannot be reached, the maximum obtainable angle must be used.

(c)
Thetowingloads speci.edinparagraph(d)ofthis section mustbe reacted asfollows:

(1)
The side component of thetowingload atthe maingear mustbe reactedby a side force at the static ground line of the wheel to which the load is applied.

(2)
Thetowingloadsatthe auxiliarygearand thedrag componentsof thetowing loads at the main gear must be reacted as follows :

(i)
A reaction with a maximum value equal to the vertical reaction must be applied at the axle of the wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied.

(ii)
The loads must be reacted by airplane inertia.

(d)
The prescribed towing loads are as follows :

Load
Tow point Position Magnitude No. Direction
Main gear. 0.75 FTOW 1 per main gear unit. 2 3 4
Forward, parallel to drag axis.
Forward, at 30dto drag axis.
Aft, parallel to drag axis.
Aft, at 30dto drag axis.

Auxiliary gear. Swiveled 1.0FTOW 5 Forward. forward. 6 Aft.
Swiveled aft.
Swiveled 45dfrom forward. Swiveled 45dfrom aft.
. . .do
0.5FTOW
. . .do 11 12
7  Forward. 
8  Aft. 
9  Forward, in plane of wheel. 
10  Aft, in plane of wheel. 

Forward, in plane of wheel. Aft, in plane of wheel.
Amdt. 25-23, E.. 5/8/70
FAR 25.511 : Ground load : unsymmetrical loads on multiple-wheel units.
(a)
General.Multiple-wheellandinggearunits areassumed tobe subjected tothelimit groundloadsprescribedinthis subpartunderparagraphs(b) through(f) ofthis section. In addition–

(1)
Atandem strutgear arrangementis a multiple-wheel unit; and

(2)
In determining the total load on a gear unit with respect to the provisions ofparagraphs(b) through(f) ofthis section,the transverse shiftin theload centroid, due to unsymmetrical load distribution on the wheels, may be ne-glected.

(b)
Distribution oflimit loads to wheels; tiresin.ated.Thedistribution ofthelimitloads among the wheels of the landinggear must be establishedfor eachlanding, taxiing, and ground handling condition, taking into account the e.ects of the following factors :

′
Elodie Roux. Septembre 2003
Subpart C : Structure

(1)
The number of wheels and theirphysical arrangements.For truck type landing gear units, the e.ects of any seesaw motion of the truck during the landing impact must be considered in determining the maximum design loads for the fore and aft wheel pairs.
　
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本文鏈接地址：FAA規章 美國聯邦航空規章 Federal Aviation Regulations 3(60)