(b)
Compliancewithparagraph(a) ofthissectionmustbe shownby tests simulating service conditions.
FAR 29.691 : Autorotation control mechanism.
Each main rotor blade pitch control mechanism must allow rapid entry into autoro-tation after power failure.
FAR 29.695 : Power boost and power-operated control system.
(a)
If apowerboost orpower-operated control system is used, an alternate system must be immediately available that allows continued safe .ight and landing in the event of–
(1)
Any singlefailureinthepowerportion of the system; or
(2)
The failure of all engines.
(b)
Each alternate system may be a duplicate power portion or a manually operated mechanical system.Thepowerportionincludes thepower source(such ashydraulic pumps), and such items as valves, lines, and actuators.
(c)
Thefailure of mechanicalparts(such aspiston rods andlinks), and thejamming of power cylinders, must be considered unless they are extremely improbable.
74.4 Landing Gear
FAR 29.723 : Shock absorption tests.
The landing inertia load factor and the reserve energy absorption capacity of the landing gear must be substantiated by the tests prescribed in Secs. 29.725 and 29.727, respectively.These tests mustbe conducted on the complete rotorcraft or on units consis-ting of wheel, tire, and shock absorber in their proper relation.
FAR 29.725 : Limit drop test.
The limit drop test must be conducted as follows :
(a)
Thedrop height mustbe[atleast8inches.]
(1)
13 inches from the lowest point of the landing gear to the ground; or
(2)
Anylesserheight, notless than eightinches, resultingin adropcontact velocity equal tothegreatestprobablesinking speedlikely to occuratground contact in normal power-o. landings.
(b)
If considered, the rotor lift speci.ed in Sec. 29.473(a) must be introduced into the drop test by appropriate energy absorbing devices or by the use of an e.ective mass.
(c)
Eachlandinggear unit mustbetestedinthe attitude simulating thelanding condi-tion that is most critical from the standpoint of the energy to be absorbed by it.
′
Elodie Roux. Septembre 2003
Subpart D : Design and Construction
(d) When an e.ective massis usedin showing compliancewithparagraph(b) ofthis
section, thefollowingformulae maybe used instead of more rational computations. h+(1 .L)d
We = W h+ d
W
n = nj We + L
where :
We :thee.ectiveweighttobeusedinthedrop test (lbs.);
W = WM :formaingearunits,equal tothestaticreactiononthepar-(lbs.) ticular unit with the rotorcraftin the most critical attitude. A rational method may be used in computing a main gear static reaction, taking into consideration the moment arm between the main wheel reaction and the rotorcraft center of gravity.
W = WN : for nose gear units, equal to the vertical component of the (lbs.) static reaction that would exist at the nose wheel, assuming thatthe massof the rotorcraft acts atthe center ofgravity and exerts a force of 1.0g downward and 0.25g forward.
W = WT : for tailwheel units, equal to whichever of the following is (lbs.) critical :
(1)
The static weight on the tailwheel with the rotorcraft resting on all wheels; or
(2)
The vertical component of the ground reaction that would occur at the tailw-heel assuming thatthemassof the rotorcraft actsatthe centerofgravity and exerts a force of 1g downward with the rotorcraft in the maximum nose-up attitude considered in the nose-up landing conditions.
h : speci.ed free drop height (inches).
L : ratio of assumed rotor lift to the rotorcraft 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 5(40)
