Amdt. 29-31, E.. 10/22/90
73.4 Ground Loads
FAR 29.471 : General.
(a) Loads and equilibrium. For limit ground loads–
(1)
The limitgroundloads obtained in the landing conditions in thispart must be considered to be external loads that would occur in the rotorcraft structure if it were acting as a rigidbody; and

(2)
In each speci.edlanding condition,the externalloads mustbeplacedin equi-librium with linear and angular inertia loads in a rational or conservative manner.

(b)
Critical centers of gravity.The critical centers ofgravity withinthe rangefor which certi.cation is requested must be selected so that the maximum design loads are obtained in each landing gear element.

FAR 29.473 : Ground loading conditions and assumptions.

(a)
[For speci.ed landing conditions, a design maximum weight must be used that is notlessthanthe maximumweight.A rotorlift maybeassumed toactthrough the center ofgravitythroughoutthelandingimpact.Thislift may not exceedtwo-thirds of the design maximum weight.

(b)
Unless otherwiseprescribed,for eachspeci.edlanding condition, the rotorcraft must be designed for a limit load factor of not less than the limit inertia load factor substantiated under Sec. 29.725.

(c)
Triggering or actuating devices for additional or supplementary energy absorption may not fail under loads established in the tests prescribed in Secs. 29.725 and 29.727, but the factor of safety prescribed in Sec. 29.303 need not be used.]

Amdt. 29-3, E.. 2/25/68
FAR 29.475 : Tires and shock absorbers.
Unless otherwise prescribed, for each speci.ed landing condition, the tires must be assumed to bein their staticposition and the shock absorbers to be in their most critical position.
FAR 29.477 : Landing gear arrangement.
Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft, and one or more wheels forward, of the center of gravity.
FAR 29.479 : Level landing conditions.
(a)
Attitudes.Under each oftheloading conditionsprescribedinparagraph(b) ofthis section, the rotorcraft is assumed to be in each of the following level landing atti-tudes :

(1)
An attitude in which each wheel contacts the ground simultaneously.

(2)
An attitudein whichthe aftwheels contact theground with theforward wheels just clear of the ground.

(b)
Loading conditions.The rotorcraft mustbedesignedforthefollowinglandingloading conditions :

(1)
Vertical loads applied under Sec. 29.471.

(2)
The loads resulting from a combination of the loads applied under subpara-graph(1) of thisparagraph withdrag loads at each wheel of notlessthan25 percent of the vertical load at that wheel.

′
Elodie Roux. Septembre 2003
Subpart C : Strength Requirements
(3)
The verticalload attheinstant ofpeakdrag load combined with adrag com-ponent simulating the forces required to accelerate the wheel rolling assembly up to the speci.ed ground speed, with–

(i)
Theground speedfordeterminationof the spin-uploadsbeing atleast75 percent of the optimum forward .ight speed for minimum rate of descent in autorotation; and

(ii)
The loading conditions of this subparagraph applied to the landing gear and its attaching structure only.

(4)
If there are two wheels forward, a distribution of the loads applied to those wheels under subparagraphs(1) and(2) of thisparagraphin a ratioof40 :60.

(c) Pitching moments. Pitching moments are assumed to be resisted by–
(1)
In the case of the attitude in paragraph (a)(1) of this section, the forward landing gear; and

(2)
In the case of the attitude in paragraph (a)(2) of this section, the angular inertia forces.

FAR 29.481 : Tail-down landing conditions.
　
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