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发表于 2009-4-29 13:27:53
(c) Longitudinal trim. The aeroplane mustmaintain longitudinal trim during –1-B-17Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1(1) A climb with maximum continuouspower at a speed not more than 1·3 VSR1 , with thelanding gear retracted, and the wing-flaps (i)retracted and (ii) in the take-off position;(2) Either a glide with power off at aspeed not more than 1·3 VSR1 , or an approachwithin the normal range of approach speedsappropriate to the weight and configuration withpower settings corresponding to a 3º glidepath,whichever is the most severe, with the landinggear extended, the wing-flaps retracted andextended, and with the most unfavourablecombination of centre of gravity position andweight approved for landing; and(3) Level flight at any speed from1·3 VSR1 , to VMO/MMO, with the landing gear andwing-flaps retracted, and from 1·3 VSR1 to VLEwith the landing gear extended.(d) Longitudinal, directional, and lateral trim.The aeroplane must maintain longitudinal,directional, and lateral trim (and for lateral trim, theangle of bank may not exceed 5º) at 1·3 VSR1 , duringthe climbing flight with –(1) The critical engine inoperative;(2) The remaining engines at maximumcontinuous power; and(3) The landing gear and wing-flapsretracted.(e) Aeroplanes with four or more engines. Eachaeroplane with four or more engines must alsomaintain trim in rectilinear flight with the mostunfavourable centre of gravity and at the climbspeed, configuration, and power required by CS25.123 (a) for the purpose of establishing the enroute flight path with two engines inoperative.STABILITYCS 25.171 GeneralThe aeroplane must be longitudinally, directionallyand laterally stable in accordance with the provisionsof CS 25.173 to 25.177. In addition, suitable stabilityand control feel (static stability) is required in anycondition normally encountered in service, if flighttests show it is necessary for safe operation.CS 25.173 Static longitudinal stabilityUnder the conditions specified in CS 25.175, thecharacteristics of the elevator control forces(including friction) must be as follows:(a) A pull must be required to obtain andmaintain speeds below the specified trim speed, and apush must be required to obtain and maintain speedsabove the specified trim speed. This must be shownat any speed that can be obtained except speedshigher than the landing gear or wing flap operatinglimit speeds or VFC/MFC, whichever is appropriate, orlower than the minimum speed for steady unstalledflight.(b) The airspeed must return to within 10% ofthe original trim speed for the climb, approach andlanding conditions specified in CS 25.175 (a), (c) and(d), and must return to within 7·5% of the originaltrim speed for the cruising condition specified in CS25.175 (b), when the control force is slowly releasedfrom any speed within the range specified in subparagraph (a) of this paragraph.(c) The average gradient of the stable slope ofthe stick force versus speed curve may not be lessthan 4 N (1 pound) for each 11,2 km/h (6 kt). (SeeAMC 25.173(c).)(d) Within the free return speed range specifiedin sub-paragraph (b) of this paragraph, it ispermissible for the aeroplane, without control forces,to stabilise on speeds above or below the desired trimspeeds if exceptional attention on the part of the pilotis not required to return to and maintain the desiredtrim speed and altitude.CS 25.175 Demonstration of staticlongitudinal stabilityStatic longitudinal stability must be shown asfollows:(a) Climb. The stick force curve must have astable slope at speeds between 85% and 115% of thespeed at which the aeroplane –(1) Is trimmed with –(i) Wing-flaps retracted;(ii) Landing gear retracted;(iii) Maximum take-off weight; and(iv) The maximum power or thrustselected by the applicant as an operatinglimitation for use during climb; and(2) Is trimmed at the speed for best rateof-climb except that the speed need not be lessthan 1·3 VSR1 .(b) Cruise. Static longitudinal stability must beshown in the cruise condition as follows:(1) With the landing gear retracted at highspeed, the stick force curve must have a stableslope at all speeds within a range which is the1-B-18Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1greater of 15% of the trim speed plus the resultingfree return speed range, or 93 km/h (50 kt) plusthe resulting free return speed range, above andbelow the trim speed (except that the speed rangeneed not include speeds less than 1·3 VSR1 norspeeds greater than VFC/MFC, nor speeds thatrequire a stick force of more than 222 N (50 lbf)),with –
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发表于 2009-4-29 13:28:12
(i) The wing-flaps retracted;(ii) The centre of gravity in themost adverse position (see CS 25.27);(iii) The most critical weightbetween the maximum take-off andmaximum landing weights;(iv) The maximum cruising powerselected by the applicant as an operatinglimitation (see CS 25.1521), except that thepower need not exceed that required atVMO/MMO; and(v) The aeroplane trimmed for levelflight with the power required in subparagraph (iv) above.(2) With the landing gear retracted at lowspeed, the stick force curve must have a stableslope at all speeds within a range which is thegreater of 15% of the trim speed plus the resultingfree return speed range, or 93 km/h (50 kt) plusthe resulting free return speed range, above andbelow the trim speed (except that the speed rangeneed not include speeds less than 1·3 VSR1 norspeeds greater than the minimum speed of theapplicable speed range prescribed in subparagraph (b)(1) of this paragraph, nor speeds thatrequire a stick force of more than 222 N (50 lbf)),with –(i) Wing-flaps, centre of gravityposition, and weight as specified in subparagraph (1) of this paragraph;(ii) Power required for level flightat a speed equal to2SR11·3V VMO +; and(iii) The aeroplane trimmed for levelflight with the power required in subparagraph (ii) above.(3) With the landing gear extended, thestick force curve must have a stable slope at allspeeds within a range which is the greater of 15%of the trim speed plus the resulting free returnspeed range or 93 km/h (50 kt) plus the resultingfree return speed range, above and below the trimspeed (except that the speed range need notinclude speeds less than 1·3 VSR1 , nor speedsgreater than VLE, nor speeds that require a stickforce of more than 222 N (50 lbf)), with –(i) Wing-flap, centre of gravityposition, and weight as specified in subparagraph (b)(1) of this paragraph;(ii) The maximum cruising powerselected by the applicant as an operatinglimitation, except that the power need notexceed that required for level flight at VLE;and(iii) The aeroplane trimmed for levelflight with the power required in subparagraph (ii) above.(c) Approach. The stick force curve must havea stable slope at speeds between VSW, and 1·7 VSR1with –(1) Wing-flaps in the approach position;(2) Landing gear retracted;(3) Maximum landing weight; and(4) The aeroplane trimmed at 1·3 VSR1 ,with enough power to maintain level flight at thisspeed.(d) Landing. The stick force curve must have astable slope and the stick force may not exceed 356N (80 lbf) at speeds between VSW, and 1·7 VSR0 with –(1) Wing-flaps in the landing position;(2) Landing gear extended;(3) Maximum landing weight;(4) The aeroplane trimmed at 1·3 VSR0with –(i) Power or thrust off, and(ii) Power or thrust for level flight.CS 25.177 Static directional andlateral stability(a) The static directional stability (as shown bythe tendency to recover from a skid with the rudderfree) must be positive for any landing gear and flapposition and symmetrical power condition, at speedsfrom 1·13 VSR1 , up to VFE, VLE, or VFC/MFC (asappropriate).(b) The static lateral stability (as shown by thetendency to raise the low wing in a sideslip with theaileron controls free) for any landing gear and wingflap position and symmetric power condition, maynot be negative at any airspeed (except that speedshigher than VFE need not be considered for wingflaps extended configurations nor speeds higher than1-B-19Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1VLE for landing gear extended configurations) in thefollowing airspeed ranges (see AMC 25.177(b)):(1) From 1·13 VSR1 to VMO/MMO..(2) From VMO/MMO to VFC/MFC, unlessthe divergence is –(i) Gradual;(ii) Easily recognisable by the pilot;and(iii) Easily controllable by the pilot(c) In straight, steady, sideslips over the rangeof sideslip angles appropriate to the operation of theaeroplane, but not less than those obtained with onehalf of the available rudder control input or a ruddercontrol force of 801 N (180 lbf) , the aileron andrudder control movements and forces must besubstantially proportional to the angle of sideslip in astable sense; and the factor of proportionality mustlie between limits found necessary for safe operationThis requirement must be met for the configurationsand speeds specified in sub-paragraph (a) of thisparagraph. (See AMC 25.177(c).)(d) For sideslip angles greater than thoseprescribed by sub-paragraph (c) of this paragraph, upto the angle at which full rudder control is used or arudder control force of 801 N (180 lbf) is obtained,the rudder control forces may not reverse, andincreased rudder deflection must be needed forincreased angles of sideslip. Compliance with thisrequirement must be shown using straight, steadysideslips, unless full lateral control input is achievedbefore reaching either full rudder control input or arudder control force of 801 N (180 lbf) ; a straight,steady sideslip need not be maintained afterachieving full lateral control input. This requirementmust be met at all approved landing gear and wingflap positions for the range of operating speeds andpower conditions appropriate to each landing gearand wing-flap position with all engines operating.(See AMC 25.177(d).)CS 25.181 Dynamic stability(See AMC 25.181)
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发表于 2009-4-29 13:28:26
(a) Any short period oscillation, not includingcombined lateral-directional oscillations, occurringbetween 1·13 VSR and maximum allowable speedappropriate to the configuration of the aeroplanemust be heavily damped with the primary controls –(1) Free; and(2) In a fixed position.(b) Any combined lateral-directionaloscillations (‘Dutch roll’) occurring between 1·13 VSRand maximum allowable speed appropriate to theconfiguration of the aeroplane must be positivelydamped with controls free, and must be controllablewith normal use of the primary controls withoutrequiring exceptional pilot skill.STALLSCS 25.201 Stall demonstration(a) Stalls must be shown in straight flight andin 30º banked turns with –(1) Power off; and(2) The power necessary to maintain levelflight at 1·5 VSR1 (where VSR1 corresponds to thereference stall speed at maximum landing weightwith flaps in the approach position and thelanding gear retracted. (See AMC 25.201(a)(2).)(b) In each condition required by sub-paragraph(a) of this paragraph, it must be possible to meet theapplicable requirements of CS25.203 with –(1) Flaps, landing gear and decelerationdevices in any likely combination of positionsapproved for operation; (See AMC 25.201(b)(1).)(2) Representative weights within therange for which certification is requested;(3) The most adverse centre of gravity forrecovery; and(4) The aeroplane trimmed for straightflight at the speed prescribed in CS 25.103 (b)(6).(c) The following procedures must be used toshow compliance with CS 25.203 :(1) Starting at a speed sufficiently abovethe stalling speed to ensure that a steady rate ofspeed reduction can be established, apply thelongitudinal control so that the speed reductiondoes not exceed 0.5 m/s2(one knot per second)until the aeroplane is stalled. (See AMC25.103(c).)(2) In addition, for turning flight stalls,apply the longitudinal control to achieve airspeeddeceleration rates up to 5,6 km/h (3 kt) persecond. (See AMC 25.201(c)(2).)(3) As soon as the aeroplane is stalled,recover by normal recovery techniques.(d) The aeroplane is considered stalled whenthe behaviour of the aeroplane gives the pilot a clearand distinctive indication of an acceptable nature thatthe aeroplane is stalled. (See AMC 25.201 (d).)Acceptable indications of a stall, occurring eitherindividually or in combination, are –(1) A nose-down pitch that cannot bereadily arrested;1-B-20Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1(2) Buffeting, of a magnitude and severitythat is a strong and effective deterrent to furtherspeed reduction; or(3) The pitch control reaches the aft stopand no further increase in pitch attitude occurswhen the control is held full aft for a short timebefore recovery is initiated. (See AMC25.201(d)(3).)CS 25.203 Stall characteristics(See AMC 25.203.)(a) It must be possible to produce and to correctroll and yaw by unreversed use of aileron and ruddercontrols, up to the time the aeroplane is stalled. Noabnormal nose-up pitching may occur. Thelongitudinal control force must be positive up to andthroughout the stall. In addition, it must be possibleto promptly prevent stalling and to recover from astall by normal use of the controls.(b) For level wing stalls, the roll occurringbetween the stall and the completion of the recoverymay not exceed approximately 20º.(c) For turning flight stalls, the action of theaeroplane after the stall may not be so violent orextreme as to make it difficult, with normal pilotingskill, to effect a prompt recovery and to regaincontrol of the aeroplane. The maximum bank anglethat occurs during the recovery may not exceed –(1) Approximately 60º in the originaldirection of the turn, or 30º in the oppositedirection, for deceleration rates up to 0.5 m/s2(1knot per second); and(2) Approximately 90º in the originaldirection of the turn, or 60º in the oppositedirection, for deceleration rates in excess of 0.5m/s2(1 knot per second).CS 25.207 Stall warning(a) Stall warning with sufficient margin toprevent inadvertent stalling with the flaps andlanding gear in any normal position must be clear anddistinctive to the pilot in straight and turning flight.(b) The warning must be furnished eitherthrough the inherent aerodynamic qualities of theaeroplane or by a device that will give clearlydistinguishable indications under expected conditionsof flight. However, a visual stall warning device thatrequires the attention of the crew within the cockpitis not acceptable by itself. If a warning device isused, it must provide a warning in each of theaeroplane configurations prescribed in sub-paragraph(a) of this paragraph at the speed prescribed in subparagraphs (c) and (d) of this paragraph. Except forthe stall warning prescribed in paragraph (h)(2)(ii) ofthis section, the stall warning for flight in icingconditions prescribed in paragraph (e) of this sectionmust be provided by the same means as the stallwarning for flight in non-icing conditions. (See AMC25.207(b).)(c) When the speed is reduced at rates notexceeding 0.5 m/s
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发表于 2009-4-29 13:28:46
2(one knot per second), stallwarning must begin, in each normal configuration, ata speed, VSW, exceeding the speed at which the stallis identified in accordance with CS 25.201 (d) by notless than 9.3 km/h (five knots) or five percent CAS,whichever is greater. Once initiated, stall warningmust continue until the angle of attack is reduced toapproximately that at which stall warning began.(See AMC 25.207(c) and (d)).(d) In addition to the requirement of subparagraph(c) of this paragraph, when the speed isreduced at rates not exceeding 0.5 m/s2(one knot persecond), in straight flight with engines idling and atthe centre-of-gravity position specified in CS25.103(b)(5), VSW, in each normal configuration,must exceed VSR by not less than 5.6 km/h (threeknots) or three percent CAS, whichever is greater.(See AMC 25.207(c) and (d)).(e) In icing conditions, the stall warning marginin straight and turning flight must be sufficient toallow the pilot to prevent stalling (as defined in CS25.201(d)) when the pilot starts a recoverymanoeuvre not less than three seconds after the onsetof stall warning. When demonstrating compliancewith this paragraph, the pilot must perform therecovery manoeuvre in the same way as for theairplane in non-icing conditions. Compliance withthis requirement must be demonstrated in flight withthe speed reduced at rates not exceeding 0.5 m/sec2(one knot per second), with –(1) The more critical of the takeoff ice andfinal takeoff ice accretions defined in appendix Cfor each configuration used in the takeoff phaseof flight;(2) The en route ice accretion defined inappendix C for the en route configuration;(3) The holding ice accretion defined inappendix C for the holding configuration(s);(4) The approach ice accretion defined inappendix C for the approach configuration(s); and(5) The landing ice accretion defined inappendix C for the landing and go-aroundconfiguration(s).(f) The stall warning margin must be sufficientin both non-icing and icing conditions to allow thepilot to prevent stalling when the pilot starts arecovery manoeuvre not less than one second after1-B-21Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1the onset of stall warning in slow-down turns with atleast 1.5g load factor normal to the flight path andairspeed deceleration rates of at least 1 m/s2(2 knotsper second). When demonstrating compliance withthis paragraph for icing conditions, the pilot mustperform the recovery manoeuvre in the same way asfor the airplane in non-icing conditions. Compliancewith this requirement must be demonstrated in flightwith –(1) The flaps and landing gear in anynormal position;(2) The aeroplane trimmed for straightflight at a speed of 1.3 VSR; and(3) The power or thrust necessary tomaintain level flight at 1.3 VSR.(g) Stall warning must also be provided in eachabnormal configuration of the high lift devices that islikely to be used in flight following system failures(including all configurations covered by AeroplaneFlight Manual procedures).(h) For flight in icing conditions before the iceprotection system has been activated and isperforming its intended function, the followingrequirements apply, with the ice accretion defined inappendix C, part II(e):(1) If activating the ice protection systemdepends on the pilot seeing a specified iceaccretion on a reference surface (not just the firstindication of icing), the requirements of thissection apply, except for paragraphs (c) and (d).(2) For other means of activating the iceprotection system, the stall warning margin instraight and turning flight must be sufficient toallow the pilot to prevent stalling withoutencountering any adverse flight characteristicswhen the speed is reduced at rates not exceeding0.5 m/sec2(one knot per second) and the pilotperforms the recovery manoeuvre in the sameway as for flight in non-icing conditions.(i) If stall warning is provided bythe same means as for flight in non-icingconditions, the pilot may not start therecovery manoeuvre earlier than one secondafter the onset of stall warning.(ii) If stall warning is provided by adifferent means than for flight in non-icingconditions, the pilot may not start therecovery manoeuvre earlier than 3 secondsafter the onset of stall warning. Also,compliance must be shown with CS 25.203using the demonstration prescribed by CS25.201, except that the deceleration rates ofCS 25.201(c)(2) need not be demonstrated.GROUND HANDLING CHARACTERISTICSCS 25.231 Longitudinal stability andcontrol(a) Aeroplanes may have no uncontrollabletendency to nose over in any reasonably expectedoperating condition or when rebound occurs duringlanding or take-off. In addition –(1) Wheel brakes must operate smoothlyand may not cause any undue tendency to noseover; and(2) If a tail-wheel landing gear is used, itmust be possible, during the take-off ground runon concrete, to maintain any attitude up to thrustline level, at 75% of VSR1 .CS 25.233 Directional stability andcontrol(a) There may be no uncontrollable groundlooping tendency in 90º cross winds, up to a windvelocity of 37 km/h (20 kt) or 0·2 VSR0 , whichever isgreater, except that the wind velocity need notexceed 46 km/h (25 kt) at any speed at which theaeroplane may be expected to be operated on theground. This may be shown while establishing the90º cross component of wind velocity required by CS25.237.
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发表于 2009-4-29 13:29:03
(b) Aeroplanes must be satisfactorilycontrollable, without exceptional piloting skill oralertness, in power-off landings at normal landingspeed, without using brakes or engine power tomaintain a straight path. This may be shown duringpower-off landings made in conjunction with othertests.(c) The aeroplane must have adequatedirectional control during taxying. This may beshown during taxying prior to take-offs made inconjunction with other tests.CS 25.235 Taxying conditionThe shock absorbing mechanism may not damage thestructure of the aeroplane when the aeroplane istaxied on the roughest ground that may reasonably beexpected in normal operation.CS 25.237 Wind velocities(a) The following applies:1-B-22Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1(1) A 90º cross component of windvelocity, demonstrated to be safe for take-off andlanding, must be established for dry runways andmust be at least 37 km/h (20 kt) or 0·2 VSR0,whichever is greater, except that it need notexceed 46 km/h (25 kt).(2) The crosswind component for takeoffestablished without ice accretions is valid in icingconditions.(3) The landing crosswind componentmust be established for:(i) Non-icing conditions, and(ii) Icing conditions with thelanding ice accretion defined in appendix C.MISCELLANEOUS FLIGHT REQUIREMENTSCS 25.251 Vibration and buffeting(a) The aeroplane must be demonstrated inflight to be free from any vibration and buffeting thatwould prevent continued safe flight in any likelyoperating condition.(b) Each part of the aeroplane must bedemonstrated in flight to be free from excessivevibration under any appropriate speed and powerconditions up to VDF/MDF. The maximum speedsshown must be used in establishing the operatinglimitations of the aeroplane in accordance with CS25.1505.(c) Except as provided in sub-paragraph (d) ofthis paragraph, there may be no buffeting condition,in normal flight, including configuration changesduring cruise, severe enough to interfere with thecontrol of the aeroplane, to cause excessive fatigue tothe crew, or to cause structural damage. Stall warningbuffeting within these limits is allowable.(d) There may be no perceptible buffetingcondition in the cruise configuration in straight flightat any speed up to VMO/MMO, except that the stallwarning buffeting is allowable.(e) For an aeroplane with MD greater than 0·6or with a maximum operating altitude greater than7620 m (25,000 ft), the positive manoeuvring loadfactors at which the onset of perceptible buffetingoccurs must be determined with the aeroplane in thecruise configuration for the ranges of airspeed orMach number, weight, and altitude for which theaeroplane is to be certificated. The envelopes of loadfactor, speed, altitude, and weight must provide asufficient range of speeds and load factors for normaloperations. Probable inadvertent excursions beyondthe boundaries of the buffet onset envelopes may notresult in unsafe conditions. (See AMC 25.251(e).)CS 25.253 High-speed characteristics(a) Speed increase and recoverycharacteristics. The following speed increase andrecovery characteristics must be met:(1) Operating conditions and characteristics likely to cause inadvertent speed increases(including upsets in pitch and roll) must besimulated with the aeroplane trimmed at anylikely cruise speed up to VMO/MMO. Theseconditions and characteristics include gust upsets,inadvertent control movements, low stick forcegradient in relation to control friction, passengermovement, levelling off from climb, and descentfrom Mach to air speed limit altitudes.(2) Allowing for pilot reaction time aftereffective inherent or artificial speed warningoccurs, it must be shown that the aeroplane can berecovered to a normal attitude and its speedreduced to VMO/MMO, without –(i) Exceptional piloting strength orskill;(ii) Exceeding VD/MD, VDF/MDF, orthe structural limitations; and(iii) Buffeting that would impair thepilot’s ability to read the instruments orcontrol the aeroplane for recovery.(3) With the aeroplane trimmed at anyspeed up to VMO/MMO, there must be no reversalof the response to control input about any axis atany speed up to VDF/MDF. Any tendency to pitch,roll, or yaw must be mild and readily controllable,using normal piloting techniques. When theaeroplane is trimmed at VMO/MMO, the slope of theelevator control force versus speed curve need notbe stable at speeds greater than VFC/MFC, but theremust be a push force at all speeds up to VDF/MDFand there must be no sudden or excessivereduction of elevator control force as VDF/MDF isreached.(4) Adequate roll capability to assure aprompt recovery from a lateral upset conditionmust be available at any speed up to VDF/MDF.(See AMC 25.253(a)(4).)(5) Extension of speedbrakes. With theaeroplane trimmed at VMO/MMO, extension of thespeedbrakes over the available range ofmovements of the pilots control, at all speedsabove VMO/MMO, but not so high that VDF/MDF1-B-23Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1would be exceeded during the manoeuvre, mustnot result in:(i) An excessive positive loadfactor when the pilot does not take action tocounteract the effects of extension;(ii) Buffeting that would impair thepilot’s ability to read the instruments orcontrol the aeroplane for recovery; or(iii) A nose-down pitching moment,unless it is small. (See AMC 25.253(a)(5).)(6) Reserved(b) Maximum speed for stability characteristics,VFC/MFC. VFC/MFC is the maximum speed at whichthe requirements of CS 25.143(g), 25.147(e),25.175(b)(1), 25.177(a) through (c ), and 25.181must be met with wing-flaps and landing gearretracted. Except as noted in CS 25.253(c), VFC/MFCmay not be less than a speed midway betweenVMO/MMO and VDF/MDF, except that, for altitudeswhere Mach Number is the limiting factor, MFC neednot exceed the Mach Number at which effectivespeed warning occurs.(c) Maximum speed for stability characteristicsin icing conditions. The maximum speed for stabilitycharacteristics with the ice accretions defined inAppendix C, at which the requirements of CS25.143(g), 25.147(e), 25.175(b)(1), 25.177(a)through (c) and 25.181 must be met, is the lower of:(1) 556 km/h (300 knots) CAS,(2) VFC, or(3) A speed at which it is demonstratedthat the airframe will be free of ice accretion dueto the effects of increased dynamic pressure.CS 25.255 Out-of-trim characteristics(See AMC 25.255)(a) From an initial condition with the aeroplanetrimmed at cruise speeds up to VMO/MMO, theaeroplane must have satisfactory manoeuvringstability and controllability with the degree of out-oftrim in both the aeroplane nose-up and nose-downdirections, which results from the greater of –(1) A three-second movement of thelongitudinal trim system at its normal rate for theparticular flight condition with no aerodynamicload (or an equivalent degree of trim foraeroplanes that do not have a power-operated trimsystem), except as limited by stops in the trimsystem, including those required by CS25.655 (b)for adjustable stabilisers; or
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(2) The maximum mistrim that can besustained by the autopilot while maintaining levelflight in the high speed cruising condition.(b) In the out-of-trim condition specified insub-paragraph (a) of this paragraph, when the normalacceleration is varied from + 1 g to the positive andnegative values specified in sub-paragraph (c) of thisparagraph –(1) The stick force vs. g curve must havea positive slope at any speed up to and includingVFC/MFC; and(2) At speeds between VFC/MFC andVDF/MDF, the direction of the primary longitudinalcontrol force may not reverse.(c) Except as provided in sub-paragraphs (d)and (e) of this paragraph compliance with theprovisions of sub-paragraph (a) of this paragraphmust be demonstrated in flight over the accelerationrange –(1) –1g to 2·5 g; or(2) 0 g to 2·0 g, and extrapolating by anacceptable method to – 1 g and 2·5 g.(d) If the procedure set forth in sub-paragraph(c)(2) of this paragraph is used to demonstratecompliance and marginal conditions exist duringflight test with regard to reversal of primarylongitudinal control force, flight tests must beaccomplished from the normal acceleration at whicha marginal condition is found to exist to theapplicable limit specified in sub-paragraph (c)(1) ofthis paragraph.(e) During flight tests required by subparagraph (a) of this paragraph the limit manoeuvringload factors prescribed in CS25.333 (b) and 25.337,and the manoeuvring load factors associated withprobable inadvertent excursions beyond theboundaries of the buffet onset envelopes determinedunder CS 25.251 (e), need not be exceeded. Inaddition, the entry speeds for flight testdemonstrations at normal acceleration values lessthan 1 g must be limited to the extent necessary toaccomplish a recovery without exceeding VDF/MDF.(f) In the out-of-trim condition specified insub-paragraph (a) of this paragraph, it must bepossible from an overspeed condition at VDF/MDF, toproduce at least 1·5 g for recovery by applying notmore than 556 N (125 lbf) of longitudinal controlforce using either the primary longitudinal controlalone or the primary longitudinal control and thelongitudinal trim system. If the longitudinal trim isused to assist in producing the required load factor, itmust be shown at VDF/MDF that the longitudinal trimcan be actuated in the aeroplane nose-up directionwith the primary surface loaded to correspond to the1-B-24Annex to ED Decision 2008/006/RAmendment 5CS-25 BOOK 1least of the following aeroplane nose-up controlforces:(1) The maximum control forces expectedin service as specified in CS 25.301 and 25.397.(2) The control force required to produce1·5 g.(3) The control force corresponding tobuffeting or other phenomena of such intensitythat it is a strong deterrent to further applicationof primary longitudinal control force.1-B-25Annex to ED Decision 2008/006/RAmendment 5CS–25 BOOK 1GENERALCS 25.301 Loads(a) Strength requirements are specified in termsof limit loads (the maximum loads to be expected inservice) and ultimate loads (limit loads multiplied byprescribed factors of safety). Unless otherwiseprovided, prescribed loads are limit loads.(b) Unless otherwise provided the specified air,ground, and water loads must be placed inequilibrium with inertia forces, considering each itemof mass in the aeroplane. These loads must bedistributed to conservatively approximate or closelyrepresent actual conditions. (See AMC No. 1 to CS25.301(b).) Methods used to determine loadintensities and distribution must be validated byflight load measurement unless the methods used fordetermining those loading conditions are shown to bereliable. (See AMC No. 2 to CS 25.301(b).)(c) If deflections under load would significantlychange the distribution of external or internal loads,this redistribution must be taken into account.CS 25.302 Interaction of systems andstructuresFor aeroplanes equipped with systems that affectstructural performance, either directly or as a resultof a failure or malfunction, the influence of thesesystems and their failure conditions must be takeninto account when showing compliance with therequirements of Subparts C and D. Appendix K ofCS-25 must be used to evaluate the structuralperformance of aeroplanes equipped with thesesystems.CS 25.303 Factor of safetyUnless otherwise specified, a factor of safety of 1·5must be applied to the prescribed limit load whichare considered external loads on the structure. Whenloading condition is prescribed in terms of ultimateloads, a factor of safety need not be applied unlessotherwise specified.
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发表于 2009-4-29 13:29:44
CS 25.305 Strength and deformation(a) The structure must be able to support limitloads without detrimental permanent deformation.At any load up to limit loads, the deformation maynot interfere with safe operation.(b) The structure must be able to supportultimate loads without failure for at least 3 seconds.However, when proof of strength is shown bydynamic tests simulating actual load conditions, the3-second limit does not apply. Static tests conductedto ultimate load must include the ultimate deflectionsand ultimate deformation induced by the loading.When analytical methods are used to showcompliance with the ultimate load strengthrequirements, it must be shown that –(1) The effects of deformation are notsignificant;2) The deformations involved are fullyaccounted for in the analysis; or(3) The methods and assumptions usedare sufficient to cover the effects of thesedeformations.(c) Where structural flexibility is such that anyrate of load application likely to occur in theoperating conditions might produce transient stressesappreciably higher than those corresponding to staticloads, the effects of this rate of application must beconsidered.(d) Reserved(e) The aeroplane must be designed towithstand any vibration and buffeting that mightoccur in any likely operating condition up to VD/MD,including stall and probable inadvertent excursionsbeyond the boundaries of the buffet onset envelope.This must be shown by analysis, flight tests, or othertests found necessary by the Agency.(f) Unless shown to be extremely improbable,the aeroplane must be designed to withstand anyforced structural vibration resulting from any failure,malfunction or adverse condition in the flight controlsystem. These loads must be treated in accordancewith the requirements of CS 25.302.CS 25.307 Proof of structure(See AMC 25.307)(a) Compliance with the strength anddeformation requirements of this Subpart must beshown for each critical loading condition. Structuralanalysis may be used only if the structure conformsto that for which experience has shown this methodto be reliable. In other cases, substantiating testsmust be made to load levels that are sufficient toverify structural behaviour up to loads specified inCS 25.305.(b) Reserved(c) Reserved1-C-1Annex to ED Decision 2008/006/RAmendment 5SUBPART C – STRUCTURECS–25 BOOK 1(d) When static or dynamic tests are used to showcompliance with the requirements of CS 25.305 (b) forflight structures, appropriate material correction factorsmust be applied to the test results, unless the structure,or part thereof, being tested has features such that anumber of elements contribute to the total strength ofthe structure and the failure of one element results inthe redistribution of the load through alternate loadpaths.FLIGHT LOADSCS 25.321 General(a) Flight load factors represent the ratio of theaerodynamic force component (acting normal to theassumed longitudinal axis of the aeroplane) to theweight of the aeroplane. A positive load factor isone in which the aerodynamic force acts upward withrespect to the aeroplane.(b) Considering compressibility effects at eachspeed, compliance with the flight load requirementsof this Subpart must be shown –(1) At each critical altitude within therange of altitudes selected by the applicant;(2) At each weight from the designminimum weight to the design maximum weightappropriate to each particular flight loadcondition; and(3) For each required altitude and weight,for any practicable distribution of disposable loadwithin the operating limitations recorded in theAeroplane Flight Manual.(c) Enough points on and within the boundariesof the design envelope must be investigated to ensurethat the maximum load for each part of the aeroplanestructure is obtained.(d) The significant forces acting on theaeroplane must be placed in equilibrium in a rationalor conservative manner. The linear inertia forcesmust be considered in equilibrium with the thrust andall aerodynamic loads, while the angular (pitching)inertia forces must be considered in equilibrium withthrust and all aerodynamic moments, includingmoments due to loads on components such as tailsurfaces and nacelles. Critical thrust values in therange from zero to maximum continuous thrust mustbe considered.FLIGHT MANOEUVRE AND GUST CONDITIONSCS 25.331 Symmetric manoeuvringconditions(a) Procedure. For the analysis of themanoeuvring flight conditions specified in subparagraphs (b) and (c) of this paragraph, thefollowing provisions apply:(1) Where sudden displacement of acontrol is specified, the assumed rate of controlsurface displacement may not be less than the ratethat could be applied by the pilot through thecontrol system.
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发表于 2009-4-29 13:29:56
(2) In determining elevator angles andchordwise load distribution in the manoeuvringconditions of sub-paragraphs (b) and (c) of thisparagraph, the effect of corresponding pitchingvelocities must be taken into account. The in-trimand out-of-trim flight conditions specified in CS25.255 must be considered.(b) Manoeuvring balanced conditions.Assuming the aeroplane to be in equilibrium withzero pitching acceleration, the manoeuvring conditions A through I on the manoeuvring envelope inCS 25.333 (b) must be investigated.(c) Manoeuvring pitching conditions. Thefollowing conditions must be investigated:(1) Maximum pitch control displacementat VA. The aeroplane is assumed to be flying insteady level flight (point A1, CS 25.333 (b)) andthe cockpit pitch control is suddenly moved toobtain extreme nose up pitching acceleration. Indefining the tail load, the response of theaeroplane must be taken into account. Aeroplaneloads which occur subsequent to the time whennormal acceleration at the c.g. exceeds thepositive limit manoeuvring load factor (at pointA2 in CS.333(b)), or the resulting tailplane normalload reaches its maximum, whichever occurs first,need not be considered.(2) Checked manoeuvre between VA andVD. Nose up checked pitching manoeuvres mustbe analysed in which the positive limit loadfactor prescribed in CS 25.337 is achieved. Asa separate condition, nose down checkedpitching manoeuvres must be analysed in whicha limit load factor of 0 is achieved. In definingthe aeroplane loads the cockpit pitch controlmotions described in sub-paragraphs (i), (ii),(iii) and (iv) of this paragraph must be used:(i) The aeroplane is assumed to beflying in steady level flight at any speedbetween VA and VD and the cockpit pitchcontrol is moved in accordance with thefollowing formula:1-C-2Annex to ED Decision 2008/006/RAmendment 5CS–25 BOOK 1δ(t) = δ1 sin(ωt) for 0 t tmax ≤≤where:δ1 = the maximum availabledisplacement of the cockpit pitchcontrol in the initial direction, aslimited by the control systemstops, control surface stops, or bypilot effort in accordance withCS 25.397(b);δ(t) = the displacement of the cockpitpitch control as a function oftime. In the initial direction δ(t)is limited to δ1. In the reversedirection, δ(t) may be truncatedat the maximum availabledisplacement of the cockpit pitchcontrol as limited by the controlsystem stops, control surfacestops, or by pilot effort inaccordance with CS 25.397(b);tmax = 3π/2ω;ω= the circular frequency(radians/second) of the controldeflection taken equal to theundamped natural frequency ofthe short period rigid mode of theaeroplane, with active controlsystem effects included whereappropriate; but not less than:ωπ=VVA 2 radians per second;where:V = the speed of the aeroplane atentry to the manoeuvre.VA = the design manoeuvringspeed prescribed inCS 25.335(c)(ii) For nose-up pitchingmanoeuvres the complete cockpit pitchcontrol displacement history may bescaled down in amplitude to the extentjust necessary to ensure that the positivelimit load factor prescribed in CS 25.337is not exceeded. For nose-down pitchingmanoeuvres the complete cockpit controldisplacement history may be scaled downin amplitude to the extent just necessaryto ensure that the normal acceleration atthe c.g. does not go below 0g.
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发表于 2009-4-29 13:30:16
(iii) In addition, for cases where theaeroplane response to the specifiedcockpit pitch control motion does notachieve the prescribed limit load factorsthen the following cockpit pitch controlmotion must be used:δ(t) = δ1 sin(ωt) for 0 ≤t ≤t1δ(t) = δ1 for t1 ≤t ≤t2δ(t) = δ1 sin(ω) for t2 ≤t ≤tmaxwhere:t1 = π/2ωt2 = t1 + Δttmax = t2 + π/ω;Δt = the minimum period of timenecessary to allow theprescribed limit load factor tobe achieved in the initialdirection, but it need notexceed five seconds (seefigure below).timeδCockpit Controldeflectiont t 2 1Δt1δtmaxδ1−(iv) In cases where the cockpit pitchcontrol motion may be affected by inputsfrom systems (for example, by a stickpusher that can operate at high load factoras well as at 1g) then the effects of thosesystems must be taken into account.(v) Aeroplane loads that occurbeyond the following times need not beconsidered:(A) For the nose-up pitchingmanoeuvre, the time at which thenormal acceleration at the c.g. goesbelow 0g;(B) For the nose-downpitching manoeuvre, the time atwhich the normal acceleration at thec.g. goes above the positive limitload factor prescribed in CS 25.337;(C) tmax.1-C-3Annex to ED Decision 2008/006/RAmendment 5CS–25 BOOK 1CS 25.333 Flight manoeuvringenvelope(a) General. The strength requirements must bemet at each combination of airspeed and load factoron and within the boundaries of the representativemanoeuvring envelope (V-n diagram) of subparagraph (b) of this paragraph. This envelope mustalso be used in determining the aeroplane structuraloperating limitations as specified in CS 25.1501.(b) Manoeuvring envelopeCS 25.335 Design airspeedsThe selected design airspeeds are equivalentairspeeds (EAS). Estimated values of VS0 and VS1must be conservative.(a) Design cruising speed, VC. For VC, thefollowing apply:(1) The minimum value of VC must besufficiently greater than VB to provide forinadvertent speed increases likely to occur as aresult of severe atmospheric turbulence.(2) Except as provided in sub-paragraph25.335(d)(2), VC may not be less than VB + 1·32Uref (with Uref as specified in sub-paragraph25.341(a)(5)(i). However, VC need not exceed themaximum speed in level flight at maximumcontinuous power for the corresponding altitude.(3) At altitudes where VD is limited byMach number, VC may be limited to a selectedMach number. (See CS 25.1505.)(b) Design dive speed, VD. VD must beselected so that VC/MC is not greater than 0·8 VD/MD,or so that the minimum speed margin between VC/MCand VD/MD is the greater of the following values:(1) From an initial condition of stabilisedflight at VC/MC, the aeroplane is upset, flown for20 seconds along a flight path 7·5º below theinitial path, and then pulled up at a load factor of1·5 g (0·5 g acceleration increment). The speedincrease occurring in this manoeuvre may becalculated if reliable or conservative aerodynamicdata issued. Power as specified in CS 25.175(b)(1)(iv) is assumed until the pullup is initiated,at which time power reduction and the use of pilotcontrolled drag devices may be assumed;1-C-4Annex to ED Decision 2008/006/RAmendment 5CS–25 BOOK 1(2) The minimum speed margin must beenough to provide for atmospheric variations(such as horizontal gusts, and penetration of jetstreams and cold fronts) and for instrument errorsand airframe production variations. These factorsmay be considered on a probability basis. Themargin at altitude where MC is limited bycompressibility effects must not be less than0.07M unless a lower margin is determined usinga rational analysis that includes the effects of anyautomatic systems. In any case, the margin maynot be reduced to less than 0.05M. (See AMC25.335(b)(2))(c) Design manoeuvring speed, VA. For VA,the following apply:(1) VA may not be less than VS1 n where–(i) n is the limit positivemanoeuvring load factor at VC; and(ii) VS1 is the stalling speed withwing-flaps retracted.(2) VA and VS must be evaluated at thedesign weight and altitude under consideration.(3) VA need not be more than VC or thespeed at which the positive CNmax curve intersectsthe positive manoeuvre load factor line, whicheveris less.(d) Design speed for maximum gust intensity,VB.(1) VB may not be less than2
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发表于 2009-4-29 13:30:36
1498wacVrefUgK1 V s1⎥⎥⎦⎤⎢⎢⎣⎡+where –Vsl = the 1-g stalling speed based on CNAmaxwith the flaps retracted at the particular weight underconsideration;CNAmax = the maximum aeroplane normal forcecoefficient;Vc = design cruise speed (knots equivalentairspeed);Uref = the reference gust velocity (feet persecond equivalent airspeed) from CS 25.341(a)(5)(i);w = average wing loading (pounds persquare foot) at the particular weightunder consideration.Kg =µ 5.3.88µ+µ=cag ρw 2ρ= density of air (slugs/ft3);c = mean geometric chord of the wing(feet);g = acceleration due to gravity (ft/sec2);a = slope of the aeroplane normal forcecoefficient curve, CNA per radian;(2) At altitudes where Vc is limited byMach number –(i) VB may be chosen to provide anoptimum margin between low and highspeed buffet boundaries; and,(ii) VB need not be greater than VC.(e) Design wing-flap speeds, VF. For VF, thefollowing apply:(1) The design wing-flap speed for eachwing-flap position (established in accordance withCS 25.697 (a)) must be sufficiently greater thanthe operating speed recommended for thecorresponding stage of flight (including balkedlandings) to allow for probable variations incontrol of airspeed and for transition from onewing-flap position to another.(2) If an automatic wing-flap positioning orload limiting device is used, the speeds andcorresponding wing-flap positions programmed orallowed by the device may be used.(3) VF may not be less than –(i) 1·6 VS1 with the wing-flaps intake-off position at maximum take-offweight;(ii) 1·8 VS1 with the wing-flaps inapproach position at maximum landingweight; and(iii) 1·8 VS0 with the wing-flaps inlanding position at maximum landingweight.(f) Design drag device speeds, VDD. Theselected design speed for each drag device must besufficiently greater than the speed recommended forthe operation of the device to allow for probablevariations in speed control. For drag devicesintended for use in high speed descents, VDD may notbe less than VD. When an automatic drag devicepositioning or load limiting means is used, the speedsand corresponding drag device positions programmedor allowed by the automatic means must be used fordesign.1-C-5Annex to ED Decision 2008/006/RAmendment 5CS–25 BOOK 1CS 25.337 Limit manoeuvring loadfactors(See AMC 25.337)(a) Except where limited by maximum (static)lift coefficients, the aeroplane is assumed to besubjected to symmetrical manoeuvres resulting in thelimit manoeuvring load factors prescribed in thisparagraph. Pitching velocities appropriate to thecorresponding pull-up and steady turn manoeuvresmust be taken into account.(b) The positive limit manoeuvring load factor‘n’ for any speed up to VD may not be less than 2·1 +24 000W +10 000⎛⎝⎜⎞⎠⎟except that ‘n’ may not be less than2·5 and need not be greater than 3·8 – where ‘W’ isthe design maximum take-off weight (lb).(c) The negative limit manoeuvring load factor–(1) May not be less than –1·0 at speeds upto VC; and(2) Must vary linearly with speed fromthe value at VC to zero at VD.(d) Manoeuvring load factors lower than thosespecified in this paragraph may be used if theaeroplane has design features that make it impossibleto exceed these values in flight.CS 25.341 Gust and turbulence loads(See AMC 25.341)(a) Discrete Gust Design Criteria. Theaeroplane is assumed to be subjected to symmetricalvertical and lateral gusts in level flight. Limit gustloads must be determined in accordance with thefollowing provisions:(1) Loads on each part of the structuremust be determined by dynamic analysis. Theanalysis must take into account unsteadyaerodynamic characteristics and all significantstructural degrees of freedom including rigid bodymotions.(2) The shape of the gust must be taken asfollows:⎥
