(i)
Exceptionalpiloting strength or skill;

(ii)
Exceeding VD/MD, VDF/MDF, orthe structurallimitations; and

(iii) Bu.eting that would impair the pilot’s ability to read the instruments or control the airplane for recovery.

(3)
With the airplane trimmed at any speed up to VMO/MMO, there must be no reversal of the response to control input about any axis at any speed up to VDF/MDF. Any tendency to pitch, roll, or yaw must be mild and readily controllable, using normalpiloting techniques.Whenthe airplaneistrimmed at VMO/MMO, the slope of the elevator control force versus speed curve need not be stable at speeds greater than VFC/MFC, but there must be a push force at all speeds up to VDF/MDF and there must be no sudden or excessive reduction of elevator control force as VDF/MDF is reached.

(b)
Maximum speedfor stability characteristics, VFC/MFC. VFC/MFC is the maximum speed at whichthe requirements ofSecs.[25.143(f),]25.147(e),25.175(b)(1),25.177, and 25.181 must be met with .aps and landing gear retracted. It may not be less than a speed midwaybetween VMO/MMO and VDF/MDF, except that,for altitudes whereMach number is the limiting factor, MFC need not exceed the Mach number at which e.ective speed warning occurs.

Amdt. 25-84, E.. 7/10/95
FAR25.255 :[Out-of-trim characteristics.]
(a) [From aninitialcondition withthe airplanetrimmed at cruise speeds upto VMO/MMO, the airplane must have satisfactory maneuvering stability and controllability with the degree of out-of-trim in both the airplane nose-up and nose-down directions, which results from the greater of–
(1)
A three-second movement of the longitudinal trim system at its normal rate fortheparticular .ightconditionwith noaerodynamicload(oranequivalent degree of trim for airplanes that do not have a power-operated trim system), except aslimited by stopsin the trim system,including those requiredbySec. 25.655(b) for adjustable stabilizers; or

(2)
The maximum mistrim that can be sustained by the autopilot while maintai-ning level .ight in the high speed cruising condition.

(b)
In the out-of-trim condition speci.ed in paragraph (a) of this section, when the normal accelerationis variedfrom +1g to thepositive and negative values speci.ed inparagraph(c) of this section–

(1)
The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC ; and

(2)
At speeds between VFC/MFC and VDF/MDF the direction of the primary longitudinal control force may not reverse.

(c)
Except asprovidedinparagraphs(d) and(e) of this section, compliance with the provisionsofparagraph(a) of thissectionmustbedemonstratedin .ightoverthe acceleration range–

(1)
-1g to +2.5g; or

(2)
0 g to 2.0 g, and extrapolating by an acceptable method to -1g and +2.5g

(d)
If theprocedure setforthinparagraph(c)(2) of this sectionis used todemonstrate compliance and marginal conditions exist during .ight test with regard to reversal of primary longitudinal control force, .ight tests must be accomplished from the normal acceleration at which a marginal conditionisfoundto exist to the applicable limit speci.edinparagraph(b)(1) of this section.

(e)
During .ighttestsrequiredbyparagraph(a) ofthissection,thelimitmaneuvering load factors prescribed in Secs. 25.333(b) and 25.337, and the maneuvering load factors associated with probable inadvertent excursions beyond the boundaries of the bu.et onset envelopes determined under Sec. 25.251(e), need not be exceeded. In addition, the entry speeds for .ight test demonstrations at normal acceleration valueslessthan1g mustbelimitedtothe extent necessaryto accomplish a recovery, without exceeding VDF/MDF.

(f)
In the out-of-trim condition speci.edinparagraph(a)of this section,it mustbepos-siblefrom an overspeed condition at VDF/MDF toproduce at least1.5for recovery by applying not more than 125 pounds of longitudinal control force using either theprimary longitudinal control alone ortheprimary longitudinal control and the longitudinal trim system.If thelongitudinal trimisused to assistinproducing the required load factor, it must be shown at VDF/MDF that the longitudinal trim can be actuated in the airplane nose-up direction with primary surface loaded to correspond to the least of the following airplane nose-up control forces :
　
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本文鏈接地址：FAA規(guī)章 美國(guó)聯(lián)邦航空規(guī)章 Federal Aviation Regulations 3(42)