(b) Aeroplanes must be satisfactorily controllable, without exceptional piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path. This may be shown during power-off landings made in conjunction with other tests. (c) The aeroplane must have adequate directional control during taxying. This may be shown during taxying prior to take-offs made in conjunction with other tests. CS 25.235 Taxying condition The shock absorbing mechanism may not damage the structure of the aeroplane when the aeroplane is taxied on the roughest ground that may reasonably be expected in normal operation. CS 25.237 Wind velocities (a) The following applies: 1-B-22 Annex to ED Decision 2008/006/R Amendment 5 CS-25 BOOK 1 (1) A 90º cross component of wind velocity, demonstrated to be safe for take-off and landing, must be established for dry runways and must be at least 37 km/h (20 kt) or 0·2 VSR0, whichever is greater, except that it need not exceed 46 km/h (25 kt). (2) The crosswind component for takeoff established without ice accretions is valid in icing conditions. (3) The landing crosswind component must be established for: (i) Non-icing conditions, and (ii) Icing conditions with the landing ice accretion defined in appendix C. [Amdt. No.:25/3] MISCELLANEOUS FLIGHT REQUIREMENTS CS 25.251 Vibration and buffeting (a) The aeroplane must be demonstrated in flight to be free from any vibration and buffeting that would prevent continued safe flight in any likely operating condition. (b) Each part of the aeroplane must be demonstrated in flight to be free from excessive vibration under any appropriate speed and power conditions up to VDF/MDF. The maximum speeds shown must be used in establishing the operating limitations of the aeroplane in accordance with CS 25.1505. (c) Except as provided in sub-paragraph (d) of this paragraph, there may be no buffeting condition, in normal flight, including configuration changes during cruise, severe enough to interfere with the control of the aeroplane, to cause excessive fatigue to the crew, or to cause structural damage. Stall warning buffeting within these limits is allowable. (d) There may be no perceptible buffeting condition in the cruise configuration in straight flight at any speed up to VMO/MMO, except that the stall warning buffeting is allowable. (e) For an aeroplane with MD greater than 0·6 or with a maximum operating altitude greater than 7620 m (25,000 ft), the positive manoeuvring load factors at which the onset of perceptible buffeting occurs must be determined with the aeroplane in the cruise configuration for the ranges of airspeed or Mach number, weight, and altitude for which the aeroplane is to be certificated. The envelopes of load factor, speed, altitude, and weight must provide a sufficient range of speeds and load factors for normal operations. Probable inadvertent excursions beyond the boundaries of the buffet onset envelopes may not result in unsafe conditions. (See AMC 25.251(e).) [Amdt. No.:25/1] CS 25.253 High-speed characteristics (a) Speed increase and recovery characteristics. The following speed increase and recovery characteristics must be met: (1) Operating conditions and characteristics likely to cause inadvertent speed increases (including upsets in pitch and roll) must be simulated with the aeroplane trimmed at any likely cruise speed up to VMO/MMO. These conditions and characteristics include gust upsets, inadvertent control movements, low stick force gradient in relation to control friction, passenger movement, levelling off from climb, and descent from Mach to air speed limit altitudes. (2) Allowing for pilot reaction time after effective inherent or artificial speed warning occurs, it must be shown that the aeroplane can be recovered to a normal attitude and its speed reduced to VMO/MMO, without – (i) Exceptional piloting strength or skill; (ii) Exceeding VD/MD, VDF/MDF, or the structural limitations; and (iii) Buffeting that would impair the pilot’s ability to read the instruments or control the aeroplane for recovery. (3) With the aeroplane 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 normal piloting techniques. When the aeroplane is trimmed 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. (4) Adequate roll capability to assure a prompt recovery from a lateral upset condition must be available at any speed up to VDF/MDF. (See AMC 25.253(a)(4).) (5) Extension of speedbrakes. With the aeroplane trimmed at VMO/MMO, extension of the speedbrakes over the available range of movements of the pilots control, at all speeds above VMO/MMO, but not so high that VDF/MDF 1-B-23 Annex to ED Decision 2008/006/R Amendment 5 CS-25 BOOK 1 would be exceeded during the manoeuvre, must not result in: (i) An excessive positive load factor when the pilot does not take action to counteract the effects of extension; (ii) Buffeting that would impair the pilot’s ability to read the instruments or control 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 which the requirements of CS 25.143(g), 25.147(e), 25.175(b)(1), 25.177(a) through (c ), and 25.181 must be met with wing-flaps and landing gear retracted. Except as noted in CS 25.253(c), VFC/MFC may not be less than a speed midway between VMO/MMO and VDF/MDF, except that, for altitudes where Mach Number is the limiting factor, MFC need not exceed the Mach Number at which effective speed warning occurs. (c) Maximum speed for stability characteristics in icing conditions. The maximum speed for stability characteristics with the ice accretions defined in Appendix C, at which the requirements of CS 25.143(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 demonstrated that the airframe will be free of ice accretion due to the effects of increased dynamic pressure. [Amdt. No.:25/3] CS 25.255 Out-of-trim characteristics (See AMC 25.255) (a) From an initial condition with the aeroplane trimmed at cruise speeds up to VMO/MMO, the aeroplane must have satisfactory manoeuvring stability and controllability with the degree of out-oftrim in both the aeroplane 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 for the particular flight condition with no aerodynamic load (or an equivalent degree of trim for aeroplanes that do not have a power-operated trim system), except as limited by stops in the trim system, including those required by CS25.655 (b) for adjustable stabilisers; or |