(c)
[Pitchmaneuverconditions.Theconditionsspeci.edinparagraphs(c)(1) and(2) of this section must be investigated. The movement of the pitch control surfaces may be adjusted to take into account limitations imposed by the maximum pilot e.ort speci.ed by Sec. 25.397(b), control system stops and any indirect e.ect imposed bylimitations in the output side of the control system(for example, stalling torque or maximum rate obtainable by a power control system.)
(1)
Maximum pitch control displacement at VA. The airplane is assumed to be .yinginsteadylevel .ight(pointA1,Sec.25.333(b)) andthecockpitpitch controlis suddenly moved to obtainextreme noseuppitching acceleration.In de.ning the tailload, the response of the airplane mustbe takeninto account. Airplane loads that occur subsequent to the time when normal acceleration atthe c.g. exceedsthepositivelimit maneuvering loadfactor(atpointA2in Sec. 25.333(b)), or the resulting tailplane normal load reaches its maximum, whichever occurs .rst, need not be considered.]
(2)
Speci.ed control displacement. A checked maneuver, based on a rational pit-ching control motion vs.timepro.le, mustbe establishedin which thedesign limit load factor speci.ed in Sec. 25.337 will not be exceeded. Unless lesser values cannot be exceeded, the airplane response must result in pitching ac-celerations not less than the following :
(i) Apositivepitchingacceleration(nose up)is assumedtobe reached concur-rently withthe airplaneloadfactor of1.0(pointsA1toD1,Sec.25.333(b)). The positive acceleration must be equal to at least
39nz
V (nz .1.5) (Radians/sec.2)
where-
′
Elodie Roux. Septembre 2003
Subpart C : Structure
nz is the positive load factor at the speed under consideration; and V is the airplane equivalent speed in knots.
(ii) A negativepitching acceleration(nosedown) is assumedtobe reached concurrently withthepositive maneuvering loadfactor(pointsA2 toD2 Sec. 25.333(b)). This negative pitching acceleration must be equal to at least
.26nz
(nz .1.5) (Radians/sec.2)
V
where-nz is the positive load factor at the speed under consideration; and V is the airplane equivalent speed in knots.
(d) [Removed.]
Amdt. 25-91, E.. 7/29/97
FAR25.333 :Flight[maneuvering] envelope.
(a)
General.[The strength requirements must be met at each combination of airspeed and load factor on and within the boundaries of the representative maneuvering envelope(V-ndiagram) ofparagraph(b) ofthis section.This envelope must also be used in determining the airplane structural operating limitations as speci.ed in Sec. 25.1501.]
(b)
Maneuvering envelope. (Figure 46.1, p. 530)
Load Factor n
3
A D, D2
I
2
1
Equivalent.
0
VD Air Speed
-1
HF
Fig. 46.1 – Maneuvering envelope
(c) [Removed.] Amdt. 25-86, E.. 3/11/96
FAR 25.335 : Design airspeeds.
The selected design airspeeds are equivalent airspeeds (EAS). Estimated values of VS0 and VS1 must be conservative.
(a)
Design cruising speed, VC . For VC, the following apply :
(1)
The minimum value of VC must be su.ciently greater than VB to provide for inadvertent speed increases likely to occur as a result of severe atmospheric turbulence.
(2)
[Except as provided in Sec. 25.335(d)(2),VC may not be less than VB + 1.32 UREF (withUREF as speci.ed in Sec. 25.341(a)(5)(i)). However VC need not exceed the maximum speed in level .ight at maximum continuous power for the corresponding altitude.]
(3)
At altitudes where VD is limited by Mach number, VC may be limited to a selected Mach number.
(b)
Design dive speed, VD . VD must be selected so that VC /MC is not greater than
0.8 VD /MD, or so that the minimum speed margin between VC /MC and VD / MD is the greater of the following values : 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 3(46)
