which take-off weight is to be specified in the certificate, with the weight equal to maximum take-off weight for that altitude, the speed equal to the minimum take-off climb speed permitted in § 4a.748-T (b), the critical engine inoperative, its propeller windmilling with the propeller control in a position which would allow the engine (if operating normally and within approved limits) to develop at least 50 percent of maximumexcept-take-off engine speed, all other engines operating at the take-off power available at such altitude, the landing gear retracted, center of gravity in the most unfavorable position permitted for take-off, and the flaps in the take-off position, shall be at least 0.035 V11". [Amdt. 04-8, 7 F. R. 985, Feb. 14, 1942] § 4a.747-T Take-off determination.

The take-off data set forth in §§ 4a.748-T and 4a.749-T shall be determined over such range of weights and altitudes as the applicant may desire, with a constant take-off flap position for a particular weight and altitude, and with the operating engines at not more than the take-off power available at the particular altitude. These data shall be based on a level take-off surface with zero wind.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942]

§ 4a.748-T Speeds.

(a) Critical-engine failure speed, denoted by V1, is a true indicated air speed, chosen by the applicant, but in any case not less than the minimum speed at which the controllability is adequate to proceed safely with the take-off, using normal piloting skill, when the critical engine is suddenly made inoperative.

(b) Minimum take-off climb speed, denoted by V., is a true indicated air speed chosen by the applicant, which shall permit the rate of climb required in § 4a.746-T (c) but which shall not be less than 1.20 Vs, for two-engined airplanes, or 1.15 V., for airplanes having more than two engines, or less than 1.10 times the minimum speed at which the airplane is fully controllable in flight using normal piloting skill when the critical engine is suddenly made inoperative.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942]

§ 4a.749-T Take-off path.

The lengths and slopes of segments of the take-off path, and the location of critical points on the complete path shall be determined in accordance with the following conditions and assumptions. The location of the points defined in paragraphs (a) to (e) of this section shall be expressed in terms of the horizontal and vertical distances from the starting point.

(a) Starting point. The point from which a standing start is made with all engines operating.

(b) Critical-engine-failure point. The point at which the airplane attains speed V. (critical-engine-failure speed) when accelerated from point (a) with all engines operating.

(c) Accelerate-and-stop point. The point on the take-off surface at which the airplane can be brought safely to a stop if all engines are cut at point (b).

(d) Start-of-climb point. The point on or just clear of the take-off surface at which the airplane attains speed V, (take-off climb speed) when the critical engine is made inoperative with its propeller windmilling in low pitch at point (b).

The take-off acceleration segment, (a) to (d), shall be determined by making a continuous run up to speed V, with the critical engine cut at point (b).

(e) Retraction-completion point. The point at which landing gear retraction is completed when retraction is initiated not earlier than point (d).

(1) The initial climb segment, (d) to (e), shall be assumed to correspond to the rate of climb at speed V, with landing gear extended and windmilling propeller in low pitch.

(2) The second climb segment, beginning at point (e), shall be assumed to correspond to the rate of climb at speed V, with landing gear retracted and wind. milling propeller in high pitch, as defined in § 4a.746-T (c). This segment may continue indefinitely or may end at point (g) in accordance with paragraph (g) of this section.

(f) 50-foot height point. The point at which the airplane attains a height of 50 feet (above the take-off surface) along the take-off flight path defined in this section.

Operating correction factors for takeoff weight and take-off distance shall be determined to account for temperatures above and below standard, and when approved by the Administrator shall be included in the Airplane Flight Manual. These factors shall be obtained as set forth in paragraphs (a) and (b) of this section.

(a) For any specific airplane type, the average full temperature accountability shall be computed for the range of weights of the airplane, altitudes above sea level, and ambient temperatures required by the expected operating conditions. Accounts shall be taken of the temperature effect on both the aerodynamic characteristics of the airplane and on the engine power. The full temperature accountability shall be expressed per degree of temperature in terms of a weight correction, a take-off distance correction, and a change, if any, in the critical engine failure speed, V1.

(b) The operating correction factors for the airplane weight and take-off distance shall be at least one-half of the full accountability values. The value of V. shall be further corrected by the average amount necessary to assure that the airplane can stop within the runway length at the ambient temperature; except that the corrected value of V1 shall not be less than a minimum at which the airplane can be controlled with the critical engine inoperative. [Amdt. 48-2, 14 F. R. 3743, July 7, 1949; 14 F. R. 4477 Note, July 16, 1949; 14 F. R. 4923, Aug. 10, 1949]

§ 4a.750-T Landing determination.

The horizontal distance required to land and come to a complete stop from a point at a height of 50 feet above the landing surface shall be determined for such range of weights and altitudes as the applicant may desire. In making this determination:

(a) Immediately prior to reaching the 50-foot altitude, a steady gliding approach shall have been maintained, with a true indicated air speed of at least 1.3 Vs.

(b) The nose of the airplane shall not be depressed, nor the power increased, after reaching the 50-foot altitude. At all times during and immediately prior to the landing, the flaps shall be in the landing position, except that after the airplane is on the landing surface and the true indicated air speed has been reduced to not more than 0.9 Vs, the flap position may be changed.

(c) The operating pressures on the braking system shall not be in excess of those approved by the manufacturer of the brakes.

(d) The brakes shall not be used in such manner as to produce excessive wear of brakes or tires.

(e) The landing shall be made in such manner that there is no excessive vertical acceleration, no tendency to bounce, nose over, porpoise, ground loop, or water loop, and in such manner that its reproduction shall not require any exceptional degree of skill on the part of the pilot, or exceptionally favorable conditions. If this last condition (with respect to exceptional skill or favorable conditions) is not met, the distance to be determined shall be that considered to correspond to a piloting technique normally usable.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942]

FLIGHT CHARACTERISTICS

§ 4a.751-T Flight characteristics.

There shall be no flight characteristic which makes the airplane unairworthy. The airplane shall also meet the following requirements under all critical loading conditions within the range of center of gravity, and, except as provided in

§ 4a.753-T (d), at the maximum weight for which certification is sought.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942, as amended by Amdt. 04-2, 8 F. R. 13999, Oct. 14, 1943, and Amdt. 4a-1, 17 F. R. 11631, Dec. 20, 1952]

§ 4a.752-T Controllability and maneuverability.

The airplane shall be controllable and maneuverable during take-off, climb, level flight, glide, and landing, and it shall be possible to make a smooth transition from one flight condition to another, without requiring an exceptional degree of skill, alertness, or strength on the part of the pilot, under all conditions of operation probable for the type, including those conditions normally encountered in the event of sudden failure of any engine. It shall be possible, with power off, with flaps either retracted or in the landing position, with the center of gravity in the most unfavorable location within the certificated range, and with the airplane trimmed for a speed of 1.4 V11, to change the flap position to the opposite extreme, to make a sudden application of take-off power on all engines, or to change the speed to any value between 1.10 V11, and 1.70 Vs1, without requiring a change in the trim control or the exertion of more control force than can readily be applied with one hand for a short period. It shall not be necessary to use exceptional piloting skill in order to prevent loss of altitude when flap retraction from any position is initiated during steady horizontal flight at 1.1 Vs, with simultaneous application of not more than maximumexcept-take-off power.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942]

§ 4a.753-T Trim.

The means used for trimming the airplane shall be such that after being trimmed and without further pressure upon or movement of either the primary control or its corresponding trim control by the pilot or the automatic pilot, the airplane will maintain:

(a) Lateral and directional trim under all conditions of operation consistent with the intended use of the airplane, including operation at any speed from best rate-of-climb speed to high speed and operation in which there is greatest lateral variation in the distribution of the useful load;

(b) Longitudinal trim, under the following conditions:

(1) During climb at the best rate-ofclimb speed with maximum-except-takeoff power.

(2) During a glide with power off at a speed not in excess of 1.4 V11, and

(3) During level flight at any speed from 90 percent of high speed to the sum of V11 and 20 percent of the difference between high speed and V11';

(c) Rectilinear climbing flight with the critical engine inoperative, each other engine operating at maximumexcept-take-off power and the best rateof-climb speed under such conditions;

(d) Rectilinear flight with any two engines inoperative and each other engine operating at maximum-excepttake-off power under the following conditions:

(1) With the weight of the airplane not more than that at which there is a speed range in level flight of not less than 10 miles per hour;

(2) With the speed of the airplane not more than the high speed obtained under the conditions specified in subparagraph (1) of this paragraph less 10 miles per hour.

[Amdt. 04-8, 7 F. R. 986, Feb. 14, 1942] § 4a.754-T Stability.

The airplane shall be longitudinally, directionally, and laterally stable in accordance with the following provisions. Suitable stability and control "feel" may be required in other conditions normally encountered in service if flight tests show such stability to be necessary for safe operation.

[Amdt. 04-8, 7 F.R. 987, Feb. 14, 1942]

§ 4a.755-T Static longitudinal stability. In the flight conditions described in § 4a.756-T,

(a) At any speed which can be obtained without excessive control force and which is more than 10 miles per hour above or below the specified trim speed, but not greater than the appropriate maximum permissible speed or less than the minimum speed in steady unstalled flight, the characteristics of the elevator control forces and friction shall be such that:

(1) A pull is required to maintain speeds below the specified trim speed and

a push to maintain speeds above the specified trim speed.

(2) The control will, when unrestrained by the pilot, move continuously toward its original trim position.

(b) Where a stable slope of the stick - force versus speed curve is specified, any decrease in speed below trim speed shall require an increase in the steady pull on the elevator control and any increase in speed above trim speed shall require an increase in the steady push on the control. Such slope shall be between such limits that any substantial change in speed is clearly perceptible to the pilot through a resulting change in stick force, and that the stick force required to produce necessary changes in speed does not reach excessive values.

[Amdt. 04-8, 7 F. R. 987, Feb. 14, 1942]

§ 4a.756-T Specific stability conditions.

(a) Landing. With flaps in the sea level landing position, the landing gear extended, maximum sea level landing weight, the airplane trimmed at 1.4 Vs, and throttles closed, the stick force curve shall have a stable slope at all speeds between 1.1 Vs1 and 1.8 Vš1·

re

(b) Approach. With flaps in sea level approach position, landing gear tracted, maximum sea level landing I weight, the airplane trimmed at 1.4 V1 - and with power sufficient to maintain - level flight at this speed, the stick force curve shall have a stable slope at all I speeds between 1.1 Vs, and 1.8 V11.

(c) Climb. With flaps retracted, landing gear retracted, maximum sea level take-off weight, 75 percent of maximumexcept-take-off power, and with the airplane trimmed at 1.4 V11, the stick force curve shall have a stable slope at all speeds between 1.2 Vs1, and 1.6 Vs1.

(d) Cruising. With flaps retracted, maximum sea level take-off weight, 75 percent of maximum-except-take-off power, and with the airplane trimmed for level flight, the stick force curve shall have a stable slope at all speeds obtainable with reasonable stick forces between:

(1) 1.2 V11, and the maximum permissible speed, when the landing gear is retracted;

(2) 1.2 V11 and the level flight speed, when the landing gear is extended. [Amdt. 04-8, 7 F. R. 987, Feb. 14, 1942] § 4a.757-T Dynamic longitudinal stability.

The airplane shall not be dynamically unstable longitudinally, as shown by the damping of the normal long period oscillation, under any flight condition that is likely to be maintained for more than 10 minutes in ordinary service. Compliance with this requirement shall be demonstrated under at least the following conditions:

(a) During level flight with 75 percent of maximum-except-take-off power.

(b) During a climb with 75 percent of maximum-except-take-off power at a speed equal to 75 percent of that obtained in paragraph (a) of this section.

Any short period oscillation occurring between stalling speed and maximum permissible speed shall be heavily damped with the primary controls in a fixed position.

[Amdt. 04-8, 7 F. R. 987, Feb. 14, 1942]

§ 4a.758-T Directional and lateral static stability.

The static directional stability, as shown by the tendency to recover from a skid with rudder free, shall be positive for all flap positions and symmetrical power conditions, and for all speeds from 1.2 V., up to the maximum permissible speed. The static lateral stability as shown by the tendency to raise the low wing in a sideslip shall be positive within the same limits.

1

With power off, and with that power necessary to maintain level flight with flaps in approach position at a speed of 1.6 V.,, maximum landing weight, flaps and landing gear in any position, and center of gravity in the least favorable position for recovery, it shall be possible to produce and to correct roll and yaw by unreversed use of the aileron and rudder controls up to the time when the airplane pitches in the maneuver described below. During the pitching and recovery portions of the maneuver it shall be possible to prevent appreciable rolling or yawing by normal use of the controls.

In demonstrating this quality, the order of events shall be:

(a) With trim controls adjusted for straight flight at a speed of 1.4 V11 reduce speed by means of the elevator control until the speed is steady at slightly above stalling speed; then

(b) Pull elevator control back at a normal rate until a stall is produced as evidenced by an uncontrollable downward pitching motion of the airplane, or until the control reaches the stop. Normal use of the elevator control for recovery may be made after such pitching motion is unmistakably developed.

In any case, the airplane shall not pitch excessively before recovery is completed.

The airplane shall be recoverable without difficulty or the use of power from the inoperative engine when it is stalled with the critical engine inoperative and the remaining engines operating at 75 percent of maximum-excepttake-off power.

[Amdt. 04-8, 7 F. R. 987, Feb. 14, 1942]

OPERATING MANUAL

§ 4a.760-T Airplane operating manual.

There shall be furnished with each airplane a copy of a manual which shall contain such information regarding the operation of the airplane as the Administrator may require, including, but not limited to, the following:

(a) All performance data secured under §§ 4a.741-T through 4a.750-T together with any pertinent descriptions of the conditions, air speeds, etc., under which such data were determined.

(b) Adequate instructions for the use and adjustment of the flap controls under § 4a.464-T.

A fireproof identification plate shall be securely attached to the structure in an accessible location where it will not likely be defaced during normal service. The identification plate shall not be placed in a location where it might be expected to be destroyed or lost in the event of an accident. The identification plate shall contain the identification data required by § 2.36 of this subchapter (14 F. R. 4036, July 16, 1949).

[CAR, Amdt. 4a-3, 14 F. R. 6769, Nov. 9, 1949] § 4a.771 Standard weights.

In computing weights the following standard values shall be used: