Amdt. 27-21, E.. 12/6/84
FAR 27.175 : Demonstration of static longitudinal stability
(a)
Climb. Static longitudinal stability must be shown in the climb condition at speeds from 0.85 VY to 1.2 VY , with–

(1)
Critical weight;

(2)
Critical center of gravity;

(3)
Maximum continuouspower;

(4)
The landing gear retracted; and

(5)
The rotorcraft trimmed at VY .

(b)
Cruise. Static longitudinal stability must be shown in the cruise condition at speeds from 0.7 VH or 0.7 VNE, whichever is less, to 1.1 VH or 1.1 VNE, whichever is less, with–

(1)
Critical weight;

(2)
Critical center of gravity;

(3)
Power for level .ight at 0.9 VH or 0.9 VNE, whichever is less;

(4)
The landing gear retracted; and

(5)
[The rotorcraft trimmedat 0.9 VH or 0.9 VNE, whichever is less.]

(c)
Autorotation. Static longitudinal stability must be shown in autorotation at airs-peeds from 0.5 times the speed for minimum rate of descent to VNE or to 1.1 VNE (power-o.)if VNE (power-o.)is established under Sec. 27.1505(c), and with–

(1)
Critical weight;

(2)
Critical center of gravity;

(3)
Power o.;

(4)
The landing gear–

(i)
Retracted; and

(ii)
Extended; and

(5)
The rotorcraft trimmed at appropriate speeds found necessary by the Admi-nistrator to demonstrate stability throughout the prescribed speed range.

(d)
Hovering.Forhelicopters, thelongitudinalcyclic control must operate with the sense anddirection of motionprescribedinSec.27.173betweenthe maximum approved rearward speed and a forward speed of 17 knots with–

(1)
Critical weight;

(2)
Critical center of gravity;

(3)
Power required to maintain an approximate constantheightinground e.ect;

(4)
Thelandinggear extended; and

(5)
The helicopter trimmed for hovering. Amdt. 27-34, E.. 11/28/97

FAR27.177 :[Staticdirectional stability.]
[Static directionalstability must bepositive with throttle and collective controlsheld constant atthetrim conditions speci.edinSec.27.175(a) and(b).This mustbe shown by steadily increasing directional control de.ection for sideslip angles up to 10'from trim.Su.cient cues must accompany sideslip to alert thepilot when approaching sideslip limits.] Amdt. 27-21, E.. 12/6/84
′
Elodie Roux. Septembre 2003
Subpart B : Flight
62.4 Ground and Water Handling Characteristics
FAR 27.231 : General
The rotorcraft must have satisfactory ground and water handling characteristics, includingfreedomfrom uncontrollable tendenciesin anycondition expectedin operation.
FAR 27.235 : Taxiing condition
The rotorcraft must be designed to withstand the loads that would occur when the rotorcraftistaxied overthe roughestground that may reasonablybeexpectedinnormal operation.
FAR 27.239 : Spray characteristics
Ifcerti.cationfor water operationis requested, no spray characteristicsduringtaxiing, takeo., or landing may obscure the vision of the pilot or damage the rotors, propellers, or other parts of the rotorcraft.
FAR 27.241 : Ground resonance
The rotorcraft may have no dangerous tendency to oscillate on the ground with the rotor turning.
62.5 Miscellaneous Flight Requirements
FAR 27.251 : Vibration
Each part of the rotorcraft must be free from excessive vibration under each appro-priate speed and power condition.
Chapitre 63
Subpart C : Strength Requirements
Sommaire
63.1General ............................... 793 FAR27.301:Loads ....................... 793 FAR27.303:Factorof safety .................. 793 FAR 27.305 : Strength and deformation . . . . . . . . . . . . 793 FAR27.307:Proof of structure. . . . . . . . . . . . . . . . . 793 FAR27.309:Designlimitations . . . . . . . . . . . . . . . . 794
　
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