applicant should provide engine power output data obtained from dynamometer tests, or the equivalent thereof for all engines that are installed in the airplane which will be used in the power calibration flight tests. The data should be sufficiently complete to allow a direct comparison with the approved certificated ratings of the engines.

(2) If the dynamometer calibration data for any engine selected for the inflight power calibration in accordance with the provisions of paragraph (b) of this section indicate that the power (based on standard atmospheric conditions for the engine) is higher than the certificated rating for the engine model, the calibrated power curve established as a result of flight tests in paragraphs (b) and (c) of this section should be corrected by applying the following power reduction: 100 percent of the power increment between the dynamometer calibration and the certificated engine rating at sea level, and 47 percent of the sea level power increment applied at an altitude of 20,000 feet with a lineal variation between these two points throughout the operating altitude range of the airplane. If the calibrated power curve established as a result of the flight tests represents an average power for more than one engine, it should be corrected by applying a power reduction equivalent to the average power difference between the dynamometer and the rated power for all engines used in the flight calibration tests. The application of other correction methods and values that will adjust the power data on the basis of the certificated rating of the engine throughout the operating altitude range of the airplane are acceptable if they can be substantiated.

(b) Selection of engines for power calibration in flight. With the exception of the critical inoperative engine, the number of engines which will be used as a basis for power calibration is left to the option of the applicant. However, the procedure specified in this paragraph should be followed to determine which engine (s) should be selected for establishing the basic calibrated power curve.

(1) The installed power of all engines should be compared in flight by means of calibrated torquemeters or other equivalent methods. If a calibrated power curve is to be established on the

basis that all engine driven accessories will be in operation during flight, the comparison should be made under full accessory load conditions. If a separate calibrated power curve is to be established for application to those test configurations where certain accessories will not be in operation, the power of all engines may be compared when these accessories are in the appropriate idling or off position. In this case it will be necessary to provide data, indicating accessory load requirements for those flight configurations and the particular engine(s) from which the power is obtained.

(2) For two-engine aircraft it is only necessary to calibrate the engine which produces the lesser power determined by comparing the results of the torquemeter indications in accordance with subparagraph (1) of this paragraph for the most critical accessory load condition and taking into consideration the appropriate power reduction when the engine dynamometer test output is above the rated power for the engine. All performance data scheduled in the Airplane Flight Manual should be based on the calibrated power curve established for this engine. If the applicant desires to calibrate the power of both engines, only the all engine operating performance data should be based on a curve representing the average power for the two engines.

(3) When the applicant desires to calibrate the power of one engine for aircraft having more than two engines, the engine selected should be that which delivers the lowest power, determined by comparing the results similarly as in the case of the two-engine aircraft in subparagraph (2) of this paragraph. All performance data scheduled in the Airplane Flight Manual should be based on the calibrated power curve established for this engine. If the applicant desires to calibrate the power of two engines, the calibrated power curve should be based on values representing an average of the two engines delivering the lowest power.

(4) The procedure in subparagraph (3) of this paragraph should be followed if the applicant desires to calibrate the power of more than two engines, however, the Airplane Flight Manual performance data should be based upon an average calibrated power curve which has been derived from not more than the actual number of engines in operation

corresponding to the test configuration for which performance is established. This procedure is not necessary, for example, in the case where the average power curve for two and three engines is substantially equal. However, the third engine may be calibrated to obtain additional data which will permit a more accurate fairing of the calibrated power curve.

(5) If the results of the flight tests indicate that the power of any engine selected in accordance with the provisions of this paragraph exceeds rated power after the application of the dynamometer correction specified in paragraph (a) of this section, the calibrated power curve for application to performance testing should be based upon not more than certificated rated power of the engine with the power to drive the accessories deducted.

(c) Flight test procedure for calibrating engine power. The engine calibration flight tests should be conducted in accordance with the provisions specified in this paragraph.

(1) The critical altitudes of the engine should be established for takeoff power and maximum continuous power providing these critical altitudes lie below the highest operating altitude desired for certification. Critical altitudes need not be determined above the maximum operating altitude of the airplane.

(2) For engine installations specifically designed to indicate power by means of torquemeters, the engine power calibration tests as well as all performance tests which are affected by power should be obtained with calibrated torquemeters.

(3) All engine adjustments such as ignition timing, valve clearances, airfuel ratios, fuel flow rates, antidetonant injection flow rates, etc., should be maintained within approved limits for the engine. If any permanent changes are made to the engine or powerplant installation during the type certification tests, and such changes result in an engine power output less than that established in the calibrated power data, then all performance data should be corrected to this lower power.

(4) The engine power calibration tests should be conducted in an atmosphere which is free of any visible moisture.

(5) The engine power calibration tests should be conducted in the configurations that follow:

(i) Takeoff power.

Weight-maximum takeoff.

C. G. position-optional.
Wing flaps-takeoff position.
Landing gear-retracted.

Operating engine(s)—takeoff r. p. m. and manifold pressure or full throttle, mixture setting at normal position for takeoff power, carburetor air heat control at cold and cowl flaps in takeoff position (see § 4b.118-1 (d) (1)).

Critical inoperative engine-throttle closed on highest powered engine, propeller windmilling in takeoff pitch (may be feathered if automatic feathering device is installed), mixture setting at idle cut-off and cowl flaps in takeoff position (see § 4b.118–1 (d) (1)).

(ii) Maximum continuous power. Weight-maximum takeoff.

C. G. position-optional.
Wing flaps en route position.
Landing gear-retracted.

Operating engine (s)-maximum continuous r. p. m. and manifold pressure or full throttle, mixture setting at normal position, carburetor air heat control at cold and cowl flaps at FAA hot day cooling position.

Critical inoperative engine-throttle closed on highest powered engine, propeller feathered and cowl flaps in minimum drag position.

(6) Test procedure and required data: The engine power calibration tests should be conducted in a climbing attitude at the takeoff safety speed, V2, with the use of takeoff power and at the en route climb speed with the use of maximum continuous power. The climbs should be started at the lowest practicable altitude and cover the altitude range desired for certification. During these tests the engine (s) should be operated within the approved limits for r. p. m., manifold pressures, temperatures, etc. The following data should be recorded at reasonable time intervals for each power condition:

Pressure altitude.
Ambient air temperature.
Humidity.

Indicated airspeed.

Engine(s), r. p. m. and manifold pressure. Torque pressure.

Cylinder head temperatures.

Carburetor air temperature.

Fuel flow rate.

Antidetonant injection flow rate.

In addition, a record should be made of

the following items:

Fuel grade.

Wing flap position.

Landing gear position.

Cowl flap position.
Mixture setting.

Blower setting.

Accessory power loads and distribution.

(d) Engine power checks. A suitable means should be established by which engine power may be compared after overhauls with the original calibrated power data obtained as a result of the type certification tests.

[Supp. 31, 21 F.R. 8417, Nov. 3, 1956] Ꭶ 4b.111 Wing flap positions.

(a) The wing flap positions denoted respectively as the take-off, en route, approach, and landing positions shall be selected by the applicant. (See also § 4b.323.)

(b) It shall be acceptable to make the flap positions variable with weight and altitude.

§ 4b.111-1 Selection of the wing flap positions (FAA policies which apply to § 4b.111).

(a) In the selection of the wing flap positions desired for certification, the flap position indicator should show flap up, take-off, en route, approach, and landing positions. Various items of performance are required to be determined at each of these flap positions. Section 4b.120 (d) requires that the stalling speed with the flap in the "approach" position should not exceed 110 percent of the stalling speed with the flap in the "landing" position. No plans for flight testing should be made until these positions are selected unless the applicant wishes to investigate systematically the effect of flap positions upon each or several of the items of performance which should be determined at the nominal position to be selected.

(b) The selection of multiple sets of wing flap positions is permitted in order to obtain optimum performance at various airports. However, it is recommended that the approval of multiple flap position settings for any one airplane be limited to two or at the most three."

(c) A reasonable number of take-off flap settings in excess of three may be approved for operation under Civil Air Regulations, Parts 40, 41, 42, and 43 of this chapter if a dispatch procedure is established to provide pertinent oper

ating limitations for the particular takeoff involved.

[Supp. 24, 19 F. R. 4449, July 20, 1954]

§ 4b.112 Stalling speeds.

(a) The speed, V., shall denote the calibrated stalling speed, or the minimum steady flight speed at which the airplane is controllable, in miles per hour, with:

(1) Engines idling, throttles closed or not more than sufficient power for zero thrust at a speed not greater than 110 percent of the stalling speed);

(2) Propeller pitch controls in the position normally used for take-off;

(3) Landing gear extended;

(4) Wing flaps in the landing position;

(5) Cowl flaps closed;

(6) Center of gravity in the most unfavorable position within the allowable landing range;

(7) The weight of the airplane equal to the weight in connection with. which Vso is being used as a factor to determine a required performance.

(b) The speed, Vs1, shall denote the calibrated stalling speed, or the minimum steady flight speed at which the airplane is controllable, in miles per hour, with:

(1) Engines idling, throttles closed (or not more than sufficient power for zero thrust at a speed not greater than 110 percent of the stalling speed);

(2) Propeller pitch controls in the position normally used for take-off, the airplane in all other respects (flaps, landing gear, etc.) in the particular condition existing in the particular test in connection with which V1, is being used;

(3) The weight of the airplane equal to the weight in connection with which V11 is being used as a factor to determine a required performance.

The reason for recommending a limited number of flap settings is due to the increasing complexity of T-category operation with the increasing number of variables such as power ratings, take-off flap settings and associated climb speeds, temperature accountability, etc., which are contained in the Airplane Flight Manual. Each additional set of flap positions approved increases the complexity with which the performance information in the Airplane Flight Manual can be evaluated to provide the proper level of safety, particularly in the take-off flight stage.

(c) The stall speeds defined in this section shall be the minimum speeds obtained in flight tests conducted in accordance with the procedure of subparagraphs (1) and (2) of this paragraph.

(1) From a speed sufficiently above the stalling speed to assure steady conditions, the elevator control shall be applied at a rate such that the airplane speed reduction does not exceed one mile per hour per second. This maneuver shall be performed with the airplane trimmed at a speed of 1.4V11, except that airplanes utilizing adjustable stabilizers may be trimmed at a speed selected by the applicant but not less than 1.2Vs1, nor greater than 1.4V11.

(2) During the test prescribed in subparagraph (1) of this paragraph, the flight characteristics provisions § 4b.160 shall be complied with.

of

[15 F. R. 3543, June 8, 1950; 15 F. R. 4171, June 29, 1950, as amended by Amdt. 4b-3. 21 F.R. 990, Feb. 11, 1956; Amdt. 4b-11, 24 F.R. 7068, Sept. 1, 1959]

§ 4b.112-1 Procedure for determining stalling speeds (FAA policies which apply to § 4b.112(c)).

(a) Since all performance requirements are based upon some function of the stalling speeds, accurate measuring methods and careful piloting technique should be employed during the tests required for determination of these speeds. The essential items to be considered when conducting tests to determine the stalling speeds are as follows:

(1) The airspeed system should have the same characteristics as outlined in § 4b.611-1(a) (2). Preferably, an independent test airspeed system should be employed in measuring the stalling speeds such as a shielded or swivel impact pressure sensing head used in conjunction with a trailing static bomb. The airspeed system lag should be a minimum with the impact and static systems dynamically balanced to minimize the error associated with changing ambient pressure. With the above described airspeed system, the applicant may elect to use the minimum airspeed obtained during the maneuver, or may determine and apply the lag correction associated with changing airspeed (deceleration) to the minimum values obtained above. If the latter option is elected, the applicant should determine the correct lag factors to be applied under varying dV/dt conditions. If the

airspeed system is not dynamically balanced, adequate corrections should be made.

(2) A satisfactory method of determining the correct lag associated with changing airspeed to be applied for balanced systems only in subparagraph (1) of this paragraph is to simulate the airspeed variations associated with stall tests, utilizing the airspeed system installed in the aircraft. For this purpose an additional airspeed instrument having a known calibration should be inserted in the airspeed system adjacent to the pressure source, and a velocitytime history of instantaneous values for true and lagging total pressures be obtained by photo-recorder. It is necessary that a steady deceleration rate appropriate to that used during actual flight tests be maintained sufficiently long to allow the system lag to stabilize. The simulated velocity-time history should be appropriately corrected to the conditions existing in the actual stall flight tests.

(3) If the stalling speed tests are to be conducted with the propellers delivering zero thrust, some dependable method such as a propeller slipstream rake by means of which zero thrust condition can be ascertained should be available in flight. The general practice of establishing zero thrust r. p. m. by calculation is also acceptable. For the turbopropeller and turbo-jet powered aircraft of conventional design, the stall speed can be determined with flight idle power, in lieu of zero thrust, if it can be shown that this power does not materially affect the stall speed. If the stall speed is materially affected by the above power, corrections should be made to zero thrust conditions. Analytical corrections will be acceptable if satisfactory accounting is made for the effects of propeller efficiency, slipstream, altitude, and other pertinent variables. The stall speed should be determined below an altitude of 10,000 feet, where practicable, to minimize the altitude effect on flight idle power.

(4) An accurate method for dete. mining the fuel load should be established for the purpose of ascertaining the airplane's gross weight and c. g. position at the time of each stall.

(5) Test instrumentation should consist of the usual sensitive indicators, especially sensitive tachometers, in order to be able to maintain r. p. m. which

results in zero thrust. The time history during the stall should be recorded photographically, and should include those data indicated in paragraph (e) (4) of this section.

(b) The test methods required in the options that follow (see also figure 1) are for the purpose of determining accurately the stalling speed used to calculate the pertinent performance climb requirements.

The airplane loading

during these tests will depend upon the c. g. weight range desired for approval, and whether the climb requirements are based on stalling speeds obtained with a fixed, or variable, c. g. position as indicated in subparagraphs (1) and (2) of this paragraph. In any case, the stalling speeds should be based on tests conducted for the most critical c. g.-weight combination, within the allowable tolerance specified in § 4b.100-1.

(1) Climb requirement based on stalling speed at the most forward c. g. position desired for certification. (i) Under this option, the applicant should measure stalling speeds at the maximum forward c. g. position for certification and at the maximum landing weight. However, in some cases where the forward c. g. limit is variable with weight, this would require that stalling speed tests be conducted at a weight and c. g. position outside of the approved structural limit. In lieu of this, and if the applicant so desires, he may measure the stalling speeds at the maximum forward c. g. position for maximum landing weight and also at the maximum forward c. g. position desired for certification and its associated weight.

(ii) It is only necessary to conduct stall speed tests for one or two loading conditions, as indicated above, if the weight range from maximum takeoff to minimum landing weight, and the variations in c. g. positions are within the allowable tolerances specified in § 4b.100-1 (b) (2) with respect to both maximum takeoff and minimum landing weights. (See figure 1, option 1, case A.) In cases where a large variation of weight exists, it may be necessary to make an additional check of the stalling speed at the most forward c. g. position corresponding to miximum takeoff weight. (See figure 1, option 1, case B.)

(2) Climb requirement based on stalling speed varying with c. g. position. If this option is elected, the applicant should conduct a sufficient number of

tests to adequately establish the variation of stalling speed with center of gravity position. In any case, the stalling speed should be measured at the maximum forward c. g. position desired for certification and at the most rearward c. g. position desired for the purpose of varying the climb requirement with c. g. position. In the event that the above configurations do not encompass the maximum takeoff weight considering the allowable tolerances, stalling speed test should also be conducted at the maximum takeoff weight and its appropriate c. g.

(c) The deceleration rate actually utlized in each test may be obtained from the velocity-time history provided by photo-recorder data. For the purpose of determining the above deceleration rate, dv/dt should be based on the average slope of the velocity-time history, from a speed 10 percent above the minimum speed obtained with the test airspeed system, down to the minimum speed. (This method should not be used in calculating the appropriate lag corrections indicated in paragraph (a) (1) and (2) of this section.)

(d) Configurations: The stalling speed should be demonstrated in the configuration shown in subparagraphs (1) and (2) of this paragraph.

(1) Configurations for demonstrating stalling speed Vs, § 4b.112 (a).

Weight-maximum landing or maximum weight at required c. g. position.

C. g. position-as required in paragraph (b) of this section.

Wing flaps-landing position.
Landing gear-extended.

Engines-idling or not more than sufficient power for zero thrust at a speed not greater than 110 percent of the stall speed.

Propeller controls-normal takeoff pitch.
Cowl flaps closed.

Trim speed-as prescribed in § 4b.112 (c) (1).

(2) Configuration for demonstrating stalling speeds Vs,, § 4b.112 (b).

Weight-maximum landing or maximum weight at required c. g. position.

C. g. position-as required in paragraph (b) of this section.

Wing flaps en route, takeoff and approach positions.

Landing gear-retracted.

Engines-idling or not more than sufficient power for zero thrust at a speed not greater than 110 percent of the stall speed.

Propeller controls-normal takeoff pitch.
Cowl flaps-closed.

Trim speed-as prescribed in § 4b.112 (1.4 V11)