CS-25 Q25 Additional airworthiness requirements for approval of a Steep Approach Landing (SAL) capability

(See AMC to Appendix Q) (SAL) 25.1 Applicability This Appendix contains airworthiness requirements that enable an aeroplane to obtain approval for a steep approach landing capability using an approach path angle greater than or equal to 4.5° (a gradient of 7.9 %). The requirements of this Appendix cover only CS-25 Subparts B and G and they apply in lieu of CS 25.121(d). They also apply in lieu of CS 25.125 if a reduced landing distance is sought, or if the landing procedure (speed, configuration, etc.) differs significantly from normal operation, or if the screen height is greater than 50 ft. Additional requirements may apply with respect to aeroplan e systems or equipment or other relevant items such as autopilot, flight guidance, or GPWS. It is likely that the GPWS mode 1 (sink rate) envelope will need modification to prevent nuisance alerts. Also, the structural implications of the increased probability of high rates of descent at touchdown must be considered. If a steep approach approval is required for flight in icing conditions, substantiation must be provided accordingly for the steep approach condition. An applicant may choose to schedule information for an all-engines approach or for an approach with one engine inoperative. If an all-engines approach is scheduled, it is assumed that a diversion is required if an engine failure occurs prior to the decision to land. (SAL) 25.2 Definitions For the purposes of this Appendix: — Steep Approach Landing: An approach to land made using a glide path angle greater than or equal to 4.5°, as selected by the applicant. — Screen Height: The reference height above the runway surface from which the landing dist ance is measured. The screen height is a height selected by the applicant, at 50 ft or another value from 35 to 60 ft. — VREF(SAL) is the calibrated airspeed selected by the applicant used during the stabilised approach at the selected approach path angle and maintained down to the screen height defined above. VREF(SAL) may not be less than 1.23 VSR, VMCL, or a speed that provides the manoeuvring capability specified in CS 25.143(h), whichever is greater and may be different from the VREF used for standard approaches. — VREF(SAL)-1 is the calibrated airspeed selected by the applicant used during the stabilised one - engine-inoperative approach at the selected approach path angle and maintained down to the screen height defined above. VREF(SAL)-1 may not be less than VREF(SAL). (SAL) 25.3 Steep Approach Landing Distance (Applicable only if a reduced landing distance is sought, or if the landing procedure (speed, configuration, etc.) differs significantly from normal operation, or if the screen height is greate r than 50 ft.) (a) The steep approach landing distance is the horizontal distance necessary to land and to come to a complete stop from the landing screen height and must be determined (for standard temperatures, at each weight, altitude and wind within the operational limits established by the applicant for the aeroplane) as follows: (1) The aeroplane must be in the all-engines-operating or one-engine-inoperative steep approach landing configuration, as applicable. (2) A stabilised approach, with a calibrated airspeed of VREF(SAL) or VREF(SAL)-1 as appropriate, and at the selected approach angle must be maintained down to the screen height. (3) Changes in configuration, power or thrust, and speed must be made in accordance with the established procedures for service operation (see AMC 25.125(b)(3)). (4) The landing must be made without excessive vertical acceleration, tendency to bounce, nose over or ground loop and with a vertical touchdown velocity not greater than 6 ft/sec. (5) The landings may not require exceptional piloting skill or alertness. (b) The landing distance must be determined on a level, smooth, dry, hard -surfaced runway (see AMC 25.125(c)). In addition, (1) The pressures on the wheel braking systems may not exceed those specified by the brake manufacturer; (2) The brakes may not be used so as to cause excessive wear of brakes or tyres (see AMC 25.125(c)(2)); and (3) Means other than wheel brakes may be used if that means (i) Is safe and reliable; (ii) Is used so that consistent results can be expected in service; and (iii) Is such that exceptional skill is not required to control the aeroplane. (c) Reserved. (d) Reserved. (e) The landing distance data must include correction factors for not more than 50 % of the nominal wind components along the landing path opposite to the direction of landing, and not less than 150 % of the nominal wind components along the landing path in the direction of landing. (f) If any device is used that depends on the operation of any engine, and if the landing dist ance would be noticeably increased when a landing is made with that engine assumed to fail during the final stages of an all-engines-operating steep approach, the steep approach landing distance must be determined with that engine inoperative unless the us e of compensating means will result in a landing distance not more than that with each engine operating. (SAL) 25.4 Climb: One-engine-inoperative In a configuration corresponding to the normal all-engines-operating procedure in which VSR for this configuration does not exceed 110 % of the VSR for the related all-engines-operating steep approach landing configuration, the steady gradient of climb may not be less than 2.1 % for two-engined aeroplanes, 2.4 % for three-engined aeroplanes, and 2.7 % for four-engined aeroplanes, with: (a) The critical engine inoperative, the remaining engines at the go -around power or thrust setting; (b) The maximum landing weight; (c) A climb speed of VREF(SAL) and (d) The landing gear retracted. (SAL) 25.5 Safe operational and flight characteristics (a) It must be demonstrated that it is possible to complete a stabilised approach in calm air down to the commencement of the landing flare, followed by a touchdown and landing without displaying any hazardous characteristics for the following conditions (see AMC to Appendix Q, (SAL) 25.5): (1) The selected approach path angle at VREF(SAL) or VREF(SAL)-1 as appropriate; (2) An approach path angle 2° steeper than the selected approach path angle, at V REF(SAL) or VREF(SAL)-1 as appropriate; and (3) The selected approach path angle at VREF(SAL) minus 5 knots or VREF(SAL)-1 minus 5 knots as appropriate. (b) For conditions (a)(1), (a)(2), and (a)(3): (1) The demonstration must be conducted at the most critical weight and centre of gr avity, either with all-engines-operating or with the critical engine inoperative, as appropriate; (2) The rate of descent must be reduced to 3 feet per second or less before touchdown; (3) Below a height of 200 ft no action shall be taken to increase pow er or thrust apart from those small changes which are necessary to maintain an accurate approach; (4) No nose depression by use of longitudinal control shall be made after initiating the flare other than those small changes necessary to maintain a continu ous and consistent flare flight path; and (5) The flare, touchdown and landing may not require exceptional piloting skill or alertness. (c) For conditions (a)(1) and (a)(3), the flare must not be initiated above the screen height. (d) For condition (a)(2), it must be possible to achieve an approach path angle 2° steeper than the selected approach path angle in all configurations which exist down to the initiation of the flare, which must not occur above 150 % of the screen height. The flare technique used must be substantially unchanged from that recommended for use at the selected approach path angle. (e) All-engines-operating steep approach. It must be demonstrated that the aeroplane can safely transition from the all -engines-operating steep landing approach to: (1) the all-engines-operating go-around as per standard procedure; and (2) the one-engine-inoperative approach climb configuration with one engine having been made inoperative, for the following conditions: (i) The selected steep approach angle; (ii) An approach speed of VREF(SAL); (iii) The most critical weight and centre of gravity; and (iv) For propeller-powered aeroplanes, the propeller of the inoperative engine shall be at the position it automatically assumes following an engine failure at high power. (f) In addition, for propeller-powered aeroplanes, it must be demonstrated that controllability is maintained following an engine failure at approach power and with the propeller at the position it automatically assumes. (g) The height loss during the manoeuvre required by subparagraph (SAL) 25.5(e) must be determined. (h) It must be demonstrated that the aeroplane is safely controllable during a landing with one engine having been made inoperative during the final stages of an all -engines-operating steep approach for the following conditions: (1) The selected steep approach angle; (2) An approach speed of VREF(SAL); (3) The most critical weight and centre of gravity; and (4) For propeller-powered aeroplanes, the propeller of the inoperative engi ne shall be at the position it automatically assumes following an engine failure at approach power. (i) One-engine-inoperative steep approach. It must be demonstrated that the aeroplane can safely transition from the one -engine-inoperative steep landing approach to the approach climb configuration for the following conditions: (1) The selected steep approach angle; (2) An approach speed of VREF(SAL)-1; (3) The most critical weight and centre of gravity; and (4) For propeller-powered aeroplanes, the propeller of the inoperative engine may be feathered. (SAL) 25.6 Aeroplane Flight Manual For steep approach landing, the AFM shall include the following: (a) The steep approach landing distance determined in accordance with paragraph (SAL) 25.3 of this Appendix for the selected screen height and aeroplane configuration. The landing distance data may additionally include correction factors for runway slope and temperature other than standard, within the operational limits of the aeroplane, and ma y provide the required landing field length including the appropriate factors for operational variations prescribed in the relevant operating regulation. (b) The more limiting of the landing weight, altitude and temperature (WAT) limits derived in accordance with: (1) CS 25.119, and (2) The one-engine-inoperative approach climb requirement of paragraph (SAL) 25.4 of this Appendix. (c) Appropriate limitations and detailed normal, non-normal, and emergency procedures. Where an aeroplane is not approved for deliberate one-engine-inoperative steep approach landings, this limitation shall be stated. (d) A statement that the presentation of the steep approach limitations, procedures, and performance reflects the capability of the aeroplane to perform steep approa ch landings but that it does not constitute operational approval. (e) A statement of headwind and crosswind limitations if they are different from those for non - steep approaches. The tailwind limitation is 5 knots unless test evidence shows that more than 5 knots is acceptable. (f) The reference steep approach glide slope angle and the screen height used for determination of the landing distance. (g) The height loss during a go-around from the all-engines-operating steep landing approach to the approach climb configuration with one engine made inoperative, determined in accordance with (SAL) 25.5(g).