63.5 Water Loads
FAR 27.521 : Float landing conditions
If certi.cation for .oat operation is requested, the rotorcraft, with .oats, must be designed to withstand the following loading conditions (where the limit load factor is determined under Sec. 27.473(b) or assumed to be equal to that determined for wheel landing gear) :
(a)
Up-load conditions in which–
(1)
A load is applied so that, with the rotorcraft in the static level attitude, the resultant water reactionpasses vertically through the center ofgravity; and
(2)
The verticalloadprescribedin subparagraph(1) ofthisparagraphis applied simultaneously with an aft component of 0.25 times the vertical component.
(b)
A side-load condition in which–
(1)
Averticalload of0.75times the total verticalload speci.edinparagraph(a)(1) of this section is divided equally among the .oats; and
(2)
Foreach .oat,theload sharedetermined undersubparagraph(1) ofthispa-ragraph, combined with a total side load of 0.25 times the total vertical load speci.edinsubparagraph(1) of thisparagraph,isappliedtothat .oatonly.
63.6 Main Component Requirements
FAR 27.547 : Main rotor structure
(a) Each main rotor assembly(including rotorhubs andblades) mustbedesigned as prescribed in this section.
[(b) ]The main rotorstructure mustbedesigned to withstand thefollowing loadspres-cribed in Secs. 27.337 and 27.341 :
(1)
Critical .ight loads.
(2)
Limitloadsoccurring undernormal conditionsof autorotation.Forthis condi-tion, the rotor r.p.m. must be selected to include the e.ects of altitude.
[(c) ]The main rotor structure must be designed to withstand the loads simulating–
(1)
For the rotor blades, hubs, and .apping hinges, the impact force of each blade against its stop during ground operation; and
(2)
Any other critical condition expected in normal operation.
[(d) ]The main rotor structure must be designed to withstand the limit torque at any rotational speed, including zero. In addition :
(1) The limit torque need not be greater than the torque de.ned by a torque limiting device(whereprovided), and may notbelessthanthegreater of–
(i)
The maximum torque likely to be transmitted to the rotor structure in either direction; and
(ii)
The limit engine torque speci.ed in Sec. 27.361.
(2)
Thelimittorquemustbedistributed tothe rotorbladesin a rational manner. Amdt. 27-3, E.. 10/17/68
FAR 27.549 : Fuselage, landing gear, and rotor pylon structures
(a)
Eachfuselage,landinggear, androtorpylon structure mustbedesigned asprescribed in this section. Resultant rotor forces may be represented as a single force applied at the rotor hub attachment point.
(b)
Each structure must be designed to withstand–
(1)
The critical loads prescribed in Secs. 27.337 through 27.341;
(2)
The applicablegroundloadsprescribedinSecs.27.235,27.471through27.485, 27.493, 27.497, 27.501, 27.505, and 27.521; and
(3)
TheloadsprescribedinSec.27.547(d)(2) and(e).
(c)
Auxiliary rotor thrust, and the balancing air and inertia loads occurring under ac-celerated .ight conditions, must be considered.
(d)
Each engine mount and adjacent fuselage structure must be designed to withstand theloads occurringunder accelerated.ight andlanding conditions,including engine torque.
(e)
[Deleted.]
Amdt. 27-3, E.. 10/17/68
63.7 Emergency Landing Conditions
FAR 27.561 : General
(a)
The rotorcraft,althoughit maybedamagedin emergencylanding conditions onland or water, must be designed as prescribed in this section to protect the occupants under those conditions.
(b)
The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a crash landing when–
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本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 4(81)
