gory. Flight conditions. Control surface loads. A23.13 Control system loads. APPENDIX B-CONTROL SURFACE LOADINGS B23.1 General. B23.11 Control surface loads. APPENDIX C-BASIC LANDING CONDITIONS C23.1 Basic landing conditions. APPENDIX D-WHEEL SPIN-UP LOADS D23.1 Wheel spin-up loads. APPENDIX E-LIMITED WEIGHT CREDIT FOR AIRPLANES EQUIPPED WITH STANDBY POWER AUTHORITY: The provisions of this Part 23 issued under secs. 313, 601, 603, 72 Stat. 752, 775; 49 U.S.C. 1354, 1421, 1423. SOURCE: The provisions of this Part 23 contained in Docket No. 4080, 29 F.R. 17955, Dec. 18, 1964; 30 F.R. 258, Jan. 9, 1965, unless otherwise noted. SPECIAL FEDERAL REGULATIONS SFAR-23 1. Applicability. An applicant is entitled to a type certificate in the normal category for a reciprocating or turbopropeller multiengine powered small airplane that is to be certificated to carry more than 10 occupants and that is intended for use in operations under Part 135 of the Federal Aviation Regu lations if he shows compliance with the applicable requirements of Part 23 of the Federal Aviation Regulations, as supplemented or modified by the additional airworthiness requirements of this regulation. 2. References. Unless otherwise provided, all references in this regulation to specific sections of Part 23 of the Federal Aviation Regulations are those sections of Part 23 in effect on March 30, 1967. FLIGHT REQUIREMENTS 3. General. Compliance must be shown with the applicable requirements of Subpart B of Part 23 of the Federal Aviation Regulations in effect on March 30, 1967, as supplemented or modified in sections 4 through 10 of this regulation. PERFORMANCE 4. General. (a) Unless otherwise prescribed in this regulation, compliance with each applicable performance requirement in sections 4 through 7 of this regulation must be shown for ambient atmospheric conditions and still air. (b) The performance must correspond to the propulsive thrust available under the particular ambient atmospheric conditions and the particular flight condition. The available propulsive thrust must correspond to engine power or thrust, not exceeding the approved power or thrust less (1) Installation losses; and (2) The power or equivalent thrust absorbed by the accessories and services appropriate to the particular ambient atmospheric conditions and the particular flight condition. (c) Unless otherwise prescribed in this regulation, the applicant must select the takeoff, en route, and landing configurations for the airplane. (d) The airplane configuration may vary with weight, altitude, and temperature, to the extent they are compatible with the operating procedures required by paragraph (e) of this section. (e) Unless otherwise prescribed in this regulation, in determining the critical engine inoperative takeoff performance, the accelerate-stop distance, takeoff distance, changes in the airplane's configuration, speed, power, and thrust, must be made in accordance with procedures established by the applicant for operation in service. (f) Procedures for the execution of balked landings must be established by the applicant and included in the Airplane Flight Manual. (g) The procedures established under paragraphs (e) and (f) of this section must (1) Be able to be consistently executed in service by a crew of average skill; (2) Use methods or devices that are safe and reliable; and (3) Include allowance for any time delays, in the execution of the procedures, that may reasonably be expected in service. 5. Takeoff (a) General. The takeoff speeds described in paragraph (b), the acceleratestop distance described in paragraph (c), and the takeoff distance described in paragraph (d), must be determined for (1) Each weight, altitude, and ambient temperature within the operational limits selected by the applicant; (2) The selected configuration for takeoff; (3) The center of gravity in the most unfavorable position; (4) The operating engine within approved operating limitation; and (5) Takeoff data based on smooth, dry, hard-surface runway. (b) Takeoff speeds. (1) The decision speed V1 is the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot is assumed to have made a decision to continue or discontinue the takeoff. The speed V1 must be selected by the applicant but may not be less than (1) 1.10V81; (11) 1.10VMC; (111) A speed that permits acceleration to V1 and stop in accordance with paragraph (c) allowing credit for an overrun distance equal to that required to stop the airplane from a ground speed of 35 knots utilizing maximum braking; or (iv) A speed at which the airplane can be rotated for takeoff and shown to be adequate to safely continue the takeoff, using normal piloting skill, when the critical engine is suddenly made inoperative. (2) Other essential takeoff speeds necessary for safe operation of the airplane must be determined and shown in the Airplane Flight Manual. (c) Accelerate-stop distance. (1) The accelerate-stop distance is the sum of the distances necessary to (1) Accelerate the airplane from a standing start to V1; and (11) Decelerate the airplane from V, to a speed not greater than 35 knots, assuming that in the case of engine failure, failure of the critical engine is recognized by the pilot at the speed V,. The landing gear must remain in the extended position and maximum braking may be utilized during deceleration. (2) Means other than wheel brakes may be used to determine the accelerate-stop distance if that means is available with the critical engine inoperative and— (1) Is safe and reliable; (11) Is used so that consistent results can be expected under normal operating conditions; and (iii) Is such that exceptional skill is not required to control the airplane. (d) All engines operating takeoff distance. The all engine operating takeoff distance is the horizontal distance required to takeoff and climb to a height of 50 feet above the takeoff surface according to procedures in FAR 23.51(a). (e) One-engine-inoperative takeoff. The maximum weight must be determined for each altitude and temperature within the operational limits established for the airplane, at which the airplane has takeoff capability after failure of the critical engine at or above V1 determined in accordance with paragraph (b) of this section. This capability may be established (1) By demonstrating a measurably positive rate of climb with the airplane in the takeoff configuration, landing gear extended; or (2) By demonstrating the capability of maintaining flight after engine failure utilizing procedures prescribed by the applicant. 6. Climb (a) Landing climb: All-enginesoperating. The maximum weight must be determined with the airplane in the landing configuration, for each altitude, and ambient temperature within the operational limits established for the airplane and with the most unfavorable center of gravity and outof-ground effect in free air, at which the steady gradient of climb will not be less than 3.3 percent, with: (1) The engines at the power that is available 8 seconds after initiation of movement of the power or thrust controls from the minimum flight idle to the takeoff position. (2) A climb speed not greater than the approach speed established under section 7 of this regulation and not less than the greater of 1.05Mc or 1.10V81. (b) En route climb, one-engine-inoperative. (1) the maximum weight must be determined with the airplane in the en route configuration, the critical engine inoperative, the remaining engine at not more than maximum continuous power or thrust, and the most unfavorable center of gravity, at which the gradient at climb will be not less than (1) 1.2 percent (or a gradient equivalent to 0.02Vso, if greater) at 5,000 feet and an ambient temperature of 41° F.; or (11) 0.6 percent (or a gradient equivalent to 0.01Vso, if greater) at 5,000 feet and ambient temperature of 81° F. (2) The minimum climb gradient specifiled in subdivisions (1) and (ii) of subparagraph (1) of this paragraph must vary linearly beween 41° F. and 81° F. and must change at the same rate up to the maximum operational temperature approved for the airplane. 7. Landing. The landing distance must be determined for standard atmosphere at each weight and altitude in accordance with FAR 23.75(a), except that instead of the gliding approach specified in FAR 23.75 (a) (1), the landing may be preceded by a steady approach down to the 50-foot height at a gradient of descent not greater than 5.2 percent (3°) at a calibrated airspeed not less than 1.3 V81. TRIM 8. Trim-(a) Lateral and directional trim. The airplane must maintain lateral and directional trim in level flight at a speed of Va or Vxo/Mxo, whichever is lower, with landing gear and wing flaps retracted. (b) Longitudinal trim. The airplane must maintain longitudinal trim during the following conditions, except that it need not maintain trim at a speed greater than VMо/MMо: (1) In the approach conditions specified in FAR 23.161 (c) (3) through (5), except that instead of the speeds specified therein, trim must be maintained with a stick force of not more than 10 pounds down to a speed used in showing compliance with section 7 of this regulation or 1.4V whichever is lower. (2) In level flight at any speed from Vr or Vo/MMо, whichever is lower, to either Vr or 1.4V81, with the landing gear and wing flaps retracted. STABILITY 9. Static longitudinal stability. (a) In showing compliance with the provisions of FAR 23.175(b) and with paragraph (b) of this section, the airspeed must return to within ±72 percent of the trim speed. (b) Cruise stability. The stick force curve must have a stable slope for a speed range of +50 knots from the trim speed except that the speeds need not exceed Vro/Mro or be less than 1.4Vs. This speed range will be considered to begin at the outer extremes of the friction band and the stick force may not exceed 50 pounds with (1) Landing gear retracted; (111) The maximum cruising power as selected by the applicant as an operating limitation for turbine engines or 75 percent of maximum continuous power for reciprocating engines except that the power need not exceed that required at Vo/Mo; (iv) Maximum takeoff weight; and (v) The airplane trimmed for level flight with the power specified in subparagraph (iii) of this paragraph. Vrc/Mrc may not be less than a speed midway between Vо/MMо and VD/MDF, except that, for altitudes where Mach number is the limiting factor, Mrc need not exceed the Mach number at which effective speed warning occurs. (c) Climb stability. For turbopropeller powered airplanes only. In showing compliance with FAR 23.175(a), an applicant must in lieu of the power specified in FAR 23.175 (a) (4), use the maximum power or thrust selected by the applicant as an operating limitation for use during climb at the best rate of climb speed except that the speed need not be less than 1.4V81. STALLS 10. Stall warning. If artificial stall warning is required to comply with the requirements of FAR 23.207, the warning device must give clearly distinguishable indications under expected conditions of flight. The use of a visual warning device that requires the attention of the crew within the cockpit is not acceptable by itself. CONTROL SYSTEMS 11. Electric trim tabs. The airplane must meet the requirements of FAR 23.677 and in addition it must be shown that the airplane is safely controllable and that a pilot can perform all the maneuvers and operations necessary to effect a safe landing following any probable electric trim tab runaway which might be reasonably expected in service allowing for appropriate time delay after pilot recognition of the runaway. This demonstration must be conducted at the critical airplane weights and center of gravity positions. INSTRUMENTS: INSTALLATION 12. Arrangement and visibility. Each instrument must meet the requirements of FAR 23.1321 and in addition (a) Each flight, navigation, and powerplant instrument for use by any pilot must be plainly visible to him from his station with the minimum practicable deviation from his normal position and line of vision when he is looking forward along the flight path. (b) The flight instruments required by FAR 23.1303 and by the applicable operating rules must be grouped on the instrument panel and centered as nearly as practicable about the vertical plane of each pilot's forward vision. In addition (1) The instrument that most effectively indicates the attitude must be on the panel in the top center position; (2) The instrument that most effectively indicates airspeed must be adjacent to and directly to the left of the instrument in the top center position; (3) The instrument that most effectively indicates altitude must be adjacent to and directly to the right of the instrument in the top center position; and (4) The instrument that most effectively indicates direction of flight must be adjacent to and directly below the instrument in the top center position. 13. Airspeed indicating system. Each airspeed indicating system must meet the requirements of FAR 23.1323 and in addition (a) Airspeed indicating instruments must be of an approved type and must be callbrated to indicate true airspeed at sea level in the standard atmosphere with a minimum practicable instrument calibration error when the corresponding pilot and static pressures are supplied to the instruments. (b) The airspeed indicating system must be calibrated to determine the system error, 1.e., the relation between IAS and CAS, in flight and during the accelerate takeoff ground run. The ground run calibration must be obtained between 0.8 of the minimum value of V1 and 1.2 times the maximum value of V1, considering the approved ranges of altitude and weight. The ground run callbration will be determined assuming an engine failure at the minimum value of V1. (c) The airspeed error of the installation excluding the instrument calibration error, must not exceed 3 percent or 5 knots whichever is greater, throughout the speed range from Vuo to 1.3S1 with flaps retracted and from 1.3VSo to Vre with flaps in the landing position. (d) Information showing the relationship between IAS and CAS must be shown in the Airplane Flight Manual. 14. Static air vent system. The static air vent system must meet the requirements of FAR 23.1325. The altimeter system calibration must be determined and shown in the Airplane Flight Manual. OPERATING LIMITATIONS AND INFORMATION 15. Maximum operating limit speed Vxo/ Mro. Instead of establishing operating limitations based on V and Vso, the applicant must establish a maximum operating limit speed Vo/MMо in accordance with the following: (a) The maximum operating limit speed must not exceed the design cruising speed Vo and must be sufficiently below VD/MD or VDF/MDF to make it highly improbable that the latter speeds will be inadvertently exceeded in flight. (b) The speed Vxo must not exceed 0.8VD/MD or 0.8VD/MD unless flight demonstrations involving upsets as specified by the Administrator indicates a lower speed margin will not result in speeds exceeding VD/MD or VDr. Atmospheric variations, horizontal gusts, and equipment errors, and airframe production variations will be taken into account. 16. Minimum flight crew. In addition to meeting the requirements of FAR 23.1523, the applicant must establish the minimum number and type of qualified flight crew personnel sufficient for safe operation of the airplane considering (a) Each kind of operation for which the applicant desires approval; (b) The workload on each crewmember considering the following: (1) Flight path control. (2) Collision avoidance. (3) Navigation. (4) Communications. (5) Operation and monitoring of all essential aircraft systems. (6) Command decisions; and (c) The accessibility and ease of operation of necessary controls by the appropriate crewmember during all normal and emergency operations when at his flight station. 17. Airspeed indicator. The airspeed indicator must meet the requirements of FAR 23.1545 except that, the airspeed notations and markings in terms of Vro and Vr must be replaced by the Vxo/Mxo notations. The airspeed indicator markings must be easily read and understood by the pilot. A placard adjacent to the airspeed indicator is an acceptable means of showing compliance with the requirements of FAR 23.1545 (c). AIRPLANE FLIGHT MANUAL 18. General. The Airplane Flight Manual must be prepared in accordance with the requirements of FARS 23.1583 and 23.1587, and in addition the operating limitations and performance information set forth in sections 19 and 20 must be included. 19. Operating limitations. The Airplane Flight Manual must include the following limitations (a) Airspeed limitations. (1) The maximum operating limit speed Vo/Mо and a statement that this speed limit may not be deliberately exceeded in any regime of flight (climb, cruise, or descent) unless a higher speed is authorized for flight test or pilot training; (2) If an airspeed limitation is based upon compressibility effects, a statement to this effect and information as to any symptoms, the probable behavior of the airplane, and the recommended recovery procedures; and (3) The airspeed limits, shown in terms of Vo/Mxo instead of Vro and VNE. (b) Takeoff weight limitations. The maximum takeoff weight for each airport elevation, ambient temperature, and available takeoff runway length within the range selected by the applicant. This weight may not exceed the weight at which: (1) The all-engine operating takeoff distance determined in accordance with section 5(d) or the accelerate-stop distance determined in accordance with section 5(c), which ever is greater, is equal to the available runway length; (2) The airplane complies with the oneengine-inoperative takeoff requirements specified in § 5(e); and (3) The airplane complies with the oneengine-inoperative en route climb requirements specified in § 6(b), assuming that a standard temperature lapse rate exists from the airport elevation to the altitude of 5,000 feet, except that the weight may not exceed that corresponding to a temperature of 41° F. at 5,000 feet. 20. Performance information. The Airplane Flight Manual must contain the performance information determined in accordance with the provisions of the performance requirements of this regulation. The information must include the following: (a) Sufficient information so that the takeoff weight limits specified in § 19 (b) can be determined for all temperatures and altitudes within the operation limitations selected by the applicant. (b) The conditions under which the performance information was obtained, including the airspeed at the 50-foot height used to determine landing distances. (c) The performance information (determined by extrapolation and computed for the range of weights between the maximum landing and takeoff weights) for (1) Climb in the landing configuration; and (2) Landing distance. (d) Procedure established under section 4 of this regulation related to the limitations and information required by this section in the form of guidance material including any relevant limitations or information. (e) An explanation of significant or unusual flight or ground handling characteristics of the airplane. (f) Airspeeds, as indicated airspeeds, corresponding to those determined for takeoff in accordance with section 5(b). 21. Maximum operating altitudes. The maximum operating altitude to which operation is permitted, as limited by flight, structural, powerplant, functional, or equipment characteristics, must be specified in the Airplane Flight Manual. 22. Stowage provision for Airplane Flight Manual. Provision must be made for stowing the Airplane Flight Manual in a suitable fixed container which is readily accessible to the pilot. 23. Operating procedures. Procedures for restarting turbine engines in flight (including the effects of altitude) must be set forth in the Airplane Flight Manual. AIRFRAME REQUIREMENTS FLIGHT LOADS 24. Engine torque. (a) Each turbopropeller engine mount and its supporting structure must be designed for the torque effects of (1) The conditions set forth in FAR 23.361(a). (2) The limit engine torque corresponding to takeoff power and propeller speed, multiplied by a factor accounting for propeller control system malfunction, including quick feathering action, simultaneously with 1g level flight loads. In the absence of a rational analysis, a factor of 1.6 must be used. (b) The limit torque is obtained by multiplying the mean torque by a factor of 1.25. 25. Turbine engine gyroscopic loads. Each turbopropeller engine mount and its supporting structure must be designed for the gyroscopic loads that result, with the engines at maximum continuous r.p.m., under either (a) The conditions prescribed in FARS 23.351 and 23.423; or (b) All possible combinations of the following: (1) A yaw velocity of 2.5 radius per second. (2) A pitch velocity of 1.0 radians per second. (3) A normal load factor of 2.5 (4) Maximum continuous thrust. 26. Unsymmetrical loads due to engine failure. (a) Turbopropeller powered airplanes must be designed for the unsymmetrical loads resulting from the failure of the critical engine including the following conditions in combination with a single malfunction of the propeller drag limiting system, considering the probable pilot corrective action on the flight controls. (1) At speeds between Vm. and VD, the loads resulting from power failure because |