ation should correspond to that speed which would be experienced at the maximum airport altitude and weight. Discretion should be used in this test to assure remaining within safe structural and operational limits of the airplane.

(3) The accelerations may be made during take-offs and the decelerations during landings at the take-off configuration providing a minimum of one acceleration and stop run is conducted at the maximum take-off weight to determine the transition distance.

(4) Instrumentation should include means to record the airplane path relative to the runway against time in a manner to determine the horizontal distance-time history and a means should be provided to measure the wind velocity and direction, pressure altitude, engine rpm, manifold and/or torque pressure.

(1) The wind velocity should be measured adjacent to the runway at the height of 6 feet above the runway surface for test purposes. If wind effect on runway lengths is shown in the Airplane Flight Manual (see § 4b.740-1 (d) (2) (x)), the manual data should be based on reported wind velocities for a 50-foot tower height. Figure 2 should be used to calculate the wind velocity at the 50-foot height from the wind velocity measured at the 6-foot height.

(5) A special tolerance of not greater than 2 percent of the maximum takeoff weight is allowed for the acceleratestop distance tests.

(Most aft for

Weight-Maximum take-off and one lower. C. G. position-Most forward. reverse thrust decelerations.) Wing flaps Take-off position. Landing gear-Extended. Operating engines-During acceleration, all engines operating at full take-off power and rpm; cowl flaps set in take-off position (see § 4b.118-1 (d) (1)).

Inoperative engines-During deceleration, throttles closed; propellers windmilling in take-off pitch (except for failed engine with automatic feathering see § 4b.115-2); cowl flaps set in take-off position (see § 4b.118-1 (d) (1)).

(c) Test procedure and required data. (1) The airplane should be accelerated from full stop to each of three speeds up to V1, the highest value of which should correspond to at least the maximum

(4) In addition, humidity, wind direction and wind velocity should be recorded adjacent to the runway at a height of 6 feet above the runway surface. [Supp. 24, 19 F. R. 4451, July 20, 1954] § 4b.115-2 Approval of automatic propeller feathering installations for use in establishing accelerate-stop distance (FAA policies which apply to § 4b.115).

The accelerate-stop distance should be determined with the automatic propeller feathering installation feathering the propeller of the critical engine and with the other throttles closed at the instant of attainment of V.. (See §§ 4b.10-2, 4b.401-1, 4b.700-1, and Civil Air Regulations Part 4b Interpretation No. 1, § 4b.133 note)

[Supp. 23, 19 F.R. 1818, Apr. 2, 1954]

§ 4b.115-3 Reverse thrust used in accelerate-stop distance (FAA policies which apply to § 4b.115).

The policies outlined in § 4b.402-1(k) will apply.

[Supp. 25, 20 F.R. 2277, Apr. 8, 1955]

§ 4b.115-4 Accelerate-stop distance with an antiskid device installed (FAA policies which apply to

§ 4b.115).

The policies outlined in § 4b.337-4 will apply.

[Supp. 28, 21 F.R. 2558, Apr. 19, 1956]

(1) The critical engine inoperative, its propeller:

(i) Windmilling with the propeller control in a position normally used during take-off until (if applicable) its rotation has been stopped (see paragraph (c) (1) of this section),

(ii) If applicable, stopped for the remainder of the gear retraction time. (2) The landing gear extended.

(c) If applicable, the horizontal distance traversed and the height attained by the airplane in the time elapsed from the end of element (b) until the rotation of the inoperative propeller has been stopped when:

(1) The operation of stopping the propeller is initiated not earlier than the instant the airplane has attained a total height of 50 feet above the take-off surface,

2,

(2) The airplane speed is equal to V2 (3) The landing gear is retracted, (4) The inoperative propeller is windmilling with the propeller control in a position normally used during take-off.

(d) The horizontal distance traversed and the height attained by the airplane in the time elapsed from the end of element (c) until the time limit on the use of take-off power is reached, while operating at the speed V2, with:

(1) The inoperative propeller stopped, (2) The landing gear retracted.

(e) The slope of the flight path followed by the airplane ir. the configuration of element (d), but drawing not more than maximum continuous power on the operating engine (s).

§ 4b.116-1 Approval of automatic propeller feathering installations for use in establishing the take-off path (FAA policies which apply to § 4b.116).

The take-off path may be modified by permitting a feathered propeller instead of windmilling after the necessary time interval has elapsed from the instant of engine failure to complete feathering of the propeller. If it can be shown that the net work produced by the feathering propeller from the instant of engine failure to completion of feathering under all types of engine failure is positive using a datum based on feathered propeller drag, then it is permissible to assume that the propeller of the failed engine is in the feathered drag condition from the instant of attainment of the take-off climb speed V2. (See §§ 4b.10-2. 4b.401-1, and 4b.700-1.)

[Supp. 23, 19 F. R. 1818, Apr. 2, 1954]

§ 4b.116-2 Determination of the takeoff path (FAA policies which apply to § 4b.116).

(a) Recommended procedure. The recommended procedure for obtaining the take-off path is to determine the ground and climb portions separately and piece the corrected data together. The take-off flight path should be demonstrated in accordance with the following provisions:

(1) Three accelerations should be made during which the airplane is accelerated from a complete stop using all engines to speeds bracketing speed V. at which speed the critical engine fuel mixture is cut and the acceleration continued to speed V, with the inoperative engine propeller windmilling in the take-off pitch setting. If V. is less than V1, a take-off should be made on one of the above runs when the critical engine is failed at the lowest V1 speed.

7

(2) The take-off flap setting should be maintained throughout the take-off flight path. If more than one flap setting is to be used for take-off, additional tests should be included to cover the flap range (see § 4b.118-1 (d) (2)).

'When a satisfactory fully automatic propeller feathering device is installed on the airplane, advantage of such a device may be used in showing compliance with this section. See § 4b.116-1 for policies covering automatic propeller feathering systems.

(3) See § 4b.115-1 (a) (4) for instrumentation requirements.

(4) A special tolerance of not greater than 2 percent of the maximum takeoff weight is allowable for the ground portion of the accelerate distance.

(b) General test program—(1) Accelerate to take-off safety speed, V, § 4b.116 (a)(i) Configuration. These tests should be conducted in the configuration that follows:

Weight-Maximum take-off and one lower.
C. G. position-Most forward.
Wing flaps-Take-off position.
Landing gear-Extended.

Operating

engine(s)-Take-off

manifold pressure, cowl flaps in take-off position (see § 4b.118-1 (d) (1)). Critical inoperative engine-Fuel mixture cut on engine most critical performancewise (see § 4b.118-1 (e) (2)), propeller windmilling in take-off pitch (feathered if automatic feathering device is installed) and cowl flaps in take-off position (see § 4b.118-1 (d) (1)).

(ii) Test procedure and required data. The airplane should be accelerated from a complete stop to the V1 speed with all engines operating. The critical engine fuel mixture should be cut at the V1 speed and the acceleration should be continued until V2 speed is reached with the propeller of the inoperative engine windmilling in the take-off pitch. The airplane's path relative to the runway should be recorded against time in a manner to determine the horizontal distance-time history. In addition the following data should be recorded:

Wing flaps-Take-off position.
Landing gear-Extended.
Operating

engine (s)-Take-off rpm and manifold pressure or full throttle, mixture setting for take-off, carburetor air heat control at cold and cowl flaps in take-off position (see § 4b.118-1 (d) (1)). Critical inoperative engine-Throttle closed on engine most critical performancewise (see § 4b.118-1 (e) (2)), propeller windmilling in take-off pitch, (feathered if automatic feathering device is installed. see § 4b.120-1), mixture setting at idle cutoff and cowl flaps in take-off position (see § 4b.118-1(d)(1)).

(ii) Test procedure and required data. The airplane should be climbed at the take-off safety speed, V2. See § 4b.118-1 for test procedure and required data in connection with climb tests.

(3) Second take-off flight path climb segment test, § 4b.116 (c)—(i) Configuration. This test should be conducted in the configuration that follows:

Weight-Maximum take-off and one lower.
C. G. position-Optional (see § 4b.118-1
(c) (2)).

Wing flaps-Take-off position.
Landing gear-Retracted.

Operating engine (s)-Take-off rpm

and

manifold pressure or full throttle, mixture setting for take-off, carburetor air heat control at cold and cowl flaps in take-off position (see § 4b.118-1 (d) (1)). Critical inoperative engine-Throttle closed on engine most critical performancewise (see § 4b.118–1 (a) (2)), propeller windmilling in take-off pitch (feathered if automatic feathering device is installed, see § 4b.120-1), mixture setting at idle cut-off and cowl flaps in take-off position (see § 4b.118-1(d) (1)).

(ii) Test procedure and required data. The airplane should be climbed at the take-off safety speed, V2. See § 4b.118-1 for test procedure and required data in connection with climb tests.

(4) Third take-off flight path climb segment test, § 4b.116 (d)—(i) Configuration. This test should be conducted in the configuration that follows: Weight-Maximum take-off and one lower. C. G. position-Optional (see § 4b.118-1 (c) (2)).

Wing flaps-Take-off position.
Landing gear-Retracted.
Operating engine (s)-Take-off

rpm and

manifold pressure or full throttle, mixture setting for take-off, carburetor air heat control at cold and cowl flaps in take-off position (see § 4b.118-1 (d) (1)). Critical inoperative engine-Throttle closed on engine most critical performancewise (see § 4b.118-1 (e) (2)), propeller feathered and cowl flaps in minimum drag position.

(ii) Test procedure and required data. The airplane should be climbed at the take-off safety speed, V.. See §4b.118–1 for test procedure and required data in connection with climb tests.

(5) Fourth take-off flight path climb segment test, § 4b.116 (e)—(i) ConfigIuration. This configuration should be the same as for the third take-off flight path climb segment except that maximum continuous power is used on the operating engine(s).

(ii) Test procedure and required data. The airplane should be climbed at the take-off safety speed, V2. See § 4b.118-1 for test procedure and required data in connection with climb tests.

= [Supp. 24, 19 F.R. 4452, July 20, 1954, as amended by Supp. 34, 22 F.R. 6963, Aug. 29, 1957]

§ 4b.117 Temperature accountability.

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 they shall be included in the Airplane Flight Manual. These factors shall be obtained as follows:

(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. Account 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.

1

(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 V1 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 V, shall not be less than a minimum at which the airplane can be controlled with the critical engine inoperative.

§ 4b.118 Climb; general.

Compliance shall be shown with the climb requirements of §§ 4b.119 through 4b.121.

§ 4b.118-1 Test procedures for the determination of climb performance (FAA policies which apply to § 4b.118).

The test conditions and methods in paragraphs (a) through (i) of this section assume that the flight test data do not exhibit excessive scatter in points and that if such scatter makes the accuracy of the climb slopes questionable, additional tests and/or the applicants' previous flight test data for the particular configuration involved should be available. The following methods are also based upon consistent flight test data that can be properly correlated, and the use of previous acceptable test and correction methods. All new tests and correction methods will be judged upon their own merits. Polar curve or other equivalent methods are acceptable. The number of climb tests recommended for each case in paragraphs (a) and (b) of this section represents a minimum, and in certain instances it is possible that more tests may be necessary.

(a) For all take-off path segments, landing and approach climb. (1) If it is desired to show that the required climb is met at the highest altitude and heaviest weight to be certificated, a constant rate of climb curve with altitude should be acceptable. One good climb should be satisfactory if it is 50 ft./min., or more, in excess of the required climb at the highest altitude for which certification is desired. Three climbs (at same altitude) should be made if the R/C is less than 50 ft./min. in excess of the required climb. (No climb variation with weight or altitude.)

(2) If it is desired to determine the rate of climb vs. altitude curve:

(i) For a sea level engine, or the critical altitude above the maximum altitude of certification (no breaks in the curve) where the altitude range is not in excess of 8,000 feet, two good climbs at each weight over the altitude range if weight spread is in excess of 10 percent but not less than 4 climbs if only one weight is used. If the altitude range is in excess of 8,000 feet, three climbs at each weight over the altitude range (6 climbs if weight range is in excess of 10 percent) should be conducted.

(ii) For installations where a critical altitude is within the altitude range (one break in the curve) two climbs on one slope of the curve should be conducted at each weight and at least one climb on

the other slope (6 climbs for a weight spread of 10 percent or more). If the altitude range is in excess of 8,000 feet, consideration should be given to the need for a fourth climb at each weight.

(iii) For installations where two breaks in the R/C curve occur within the certification range, four climbs at each weight should be made.

(b) For all engine enroute, one-engineinoperative enroute and two-enginesinoperative enroute climbs. (1) The regulations specify that these climbs should be determined at all altitudes of expected use and weight of certification. For each weight at least the following climbs should be conducted:

(1)

(c) Weight and C. G. position. The climb tests should be conducted at maximum take-off weight for take-off climbs and at maximum landing weight for landing climbs. Climbs should also be made at an optional lower weight for both the take-off and landing configuration.

(2) Climbs may be made at any C. G. position except where the applicant elects to vary the stalling speed with C. G. position in which case the most critical C. G. position should be used. (See § 4b.112-1 (b).)

(d) Airplane configuration. (1) The cowl flaps should be set in the required position prior to conducting climb tests. The position of the cowl flaps for the take-off segments should comply with the provisions of the take-off cooling tests of § 4b.453.

(2) If more than one wing flap setting is to be used for take-off or landing, additional tests should be included to cover the flap range (see § 4b.111-1 (b)). (e) Engine power. (1) The power should be stabilized prior to conducting the climb tests. The climbs should be made at constant power or at constant throttle setting. Unless limited by engine temperature, tests should be run for at least 3 minutes at take-off power. If limited by temperature, short duration tests of approximately 1 minute duration should be acceptable provided the stabilized climbing speed is attained by accelerating from a lower speed. Where maximum continuous power is required, climb tests should be of 5 minutes duration or not necessarily more than climbs of 2,000 feet but in any case not less than 3 minutes. If climb tests are conducted for short durations, such as take-off climbs which are limited by an engine rating of two minutes for take-off power, consideration should be given to the necessity of conducting an adequate number of tests in order to obtain results which are representative of the actual performance.

(2) For the one-engine-inoperative climb tests, it may be assumed that the critical inoperative engine, performancewise, is the higher powered outboard engine unless there is evidence to indicate that another engine is more critical.

(3) For all climb tests, the power plant equipment and accessories appropriate to the specific configuration being tested should be in operation. During each test, a record should be made of such accessories in operation and of the particular engine from which power is being absorbed.

(f) Climb speeds. The climb speeds are to be selected by the applicant, but should be consistent with the performance and cooling requirements involved. The air speed should be stabilized prior to conducting the climb tests.

(g) Position of wings. The airplane's wings should be maintained in a level attitude during all take-off climb tests with one engine inoperative.

(h) Climbs to be made in free air. All climbs should be conducted in free air (without ground effect).

(i) Data. In addition to the following items, the data necessary to estab