suffix are applicable to all categories except as otherwise specified.

§ 3.20-1

Approved maneuvers for normal category aircraft (FAA interpretations which apply to § 3.20). The phrase "nonacrobatic operation" as used in § 3.20 (a) (1) is interpreted to mean that type of operation in which the aircraft is limited to those maneuvers incidental to normal flying and including stalls (except whip stalls) and turns in which the angle of bank is not in excess of 60°.

[Supp. 10, 16 F. R. 3278, Apr. 14, 1951, as amended by Supp. 14, 17 F. R. 9065, Oct. 11, 1952]

§ 3.20-2

Approved limited acrobatic maneuvers for utility category aircraft (FAA interpretations which apply to § 3.20).

The phrase "limited acrobatic maneuvers" as used in § 3.20 (a) (2) is interpreted to include spins (where approved for the particular type airplane), lazy eights, chandelles and steep turns in which the angle of bank is in excess of 60°. It is recognized that aircraft in this category are also capable of performing all normal maneuvers listed in § 3.20-1 for normal category aircraft. Although it is possible in many airplanes to perform other acrobatic maneuvers, such as loops, without exceeding airspeed and strength limitations, inexperienced or uninstructed pilots are likely to get into difficulty. It is therefore considered unwise to label such maneuvers "approved" in the Airplane Flight Manual. [Supp. 10, 16 F. R. 3278, Apr. 14, 1951, as amended by Supp. 14, 17 F. R. 9065, Oct. 11, 1952]

Subpart B-Flight Requirements

GENERAL

§ 3.61 Policy re proof of compliance.

Compliance with the requirements specified in this subpart governing functional characteristics shall be demonstrated by suitable flight or other tests conducted upon an airplane of the type, or by calculations based upon the test data referred to above, provided that the results so obtained are substantially equal in accuracy to the results of direct testing. Compliance with each require

ment must be provided at the critical combination of airplane weight and center of gravity position within the range of either for which certification is desired. Such compliance must be demonstrated by systematic investigation of all probable weight and center of gravity combinations or must be reasonably inferable from such as are investigated. § 3.62 Flight test pilot.

The applicant shall provide a person holding an appropriate pilot certificate to make the flight tests, but a designated representative of the Administrator may pilot the airplane insofar as that may be necessary for the determination of compliance with the airworthiness requirements.

§ 3.63 Noncompliance with test require

which the airplane may be safety operated.

(b) When low fuel adversely affects balance or stability, the airplane shall be so tested as to simulate the condition existing when the amount of usable fuel on board does not exceed 1 gallon for every 12 maximum continuous horsepower of the engine or engines installed. § 3.71-1 Weight and balance limitations for flight tests (FAA policies which apply to § 3.71(a)).

(a) Flight tests should be conducted at the maximum weight for which the airplane is to be certificated and at no time during the test should the weight exceed the following tolerances from the maximum weight:

Flight characteristics, general---- +5; -10. Flight characteristics, critical

items affected by weight-------- +5; - 1.

(b) The forward and rearward center of gravity during flight test loading hould be within a tolerance of 7 percent of the total travel for which the airplane s to be certificated.

(c) The airplane certificated weight nd center of gravity range should not xceed the authorized structural limits. Supp. 10, 16 F.R. 3282, Apr. 14, 1951, as mended by Supp. 14, 17 F.R. 9066, Oct. 11, 952; Supp. 26, 22 F.R. 1025, Feb. 20, 1957]

3.72 Use of ballast.

Removable ballast may be used to enble airplanes to comply with the flight equirements in accordance with the folwing provisions:

(a) The place or places for carrying allast shall be properly designed, inalled, and plainly marked as specified 1 § 3.766.

(b) The Airplane Flight Manual shall clude instructions regarding the proper sposition of the removable ballast uner all loading conditions for which such llast is necessary, as specified in 3.766 and 3.777.

3.72-1 Use of ballast (FAA policies which apply to § 3.72).

(a) Removable ballast may be used in cordance with § 3.72 provided com

pliance is demonstrated with § 3.72 (a) and (b) as related items. If the airplane does not have an Airplane Flight Manual, the instructions regarding use of the ballast should be included on the placard prescribed in § 3.766.

(b) If misuse of ballast would result in a particularly dangerous situation, such as spin recovery difficulties, a warning note should be included in the instructions.

(c) Because of the operational difficulties likely to occur in using removable ballast, it should be used only as a last resort when it is found that fixed ballast cannot accomplish the purpose without seriously limiting the utility of the airplane. On new designs manufacturers should make every effort to arrange or modify the designs to avoid the use of removable ballast.

[Supp. 10, 16 F. R. 3282, Apr. 14, 1951]

The empty weight and corresponding center of gravity location shall include all fixed ballast, the unusable fuel supply (see § 3.437), undrainable oil, full engine coolant, and hydraulic fluid. The weight and location of items of equipment installed when the airplane is weighed shall be noted in the Airplane Flight Manual.

§ 3.73-1 New production

aircraft;

empty weight and c.g. determination (FAA policies which apply to § 3.73). (a) Purpose. The purpose of this section is to provide a procedure which will permit manufacturers of new aricraft, as described in paragraph (b) of this section, to establish an average empty weight and empty c. g. for such aircraft, thus avoiding the necessity of weighing each aircraft.

(b) Coverage. Aircraft to which the procedure outlined herein may be applied are those which are newly manufactured in accordance with requirements contained in this part, and Part 4a of this subchapter (except transport category aircraft), and which are produced under the terms of a production certificate.

(c) Procedure. Manufacturers producing aircraft in accordance with the

requirements prescribed in paragraph (b) of this section who are interested in establishing an average empty weight and empty c. g. in lieu of actually weighing each aircraft, should prepare and forward through the local Aviation Safety Agent to the Chief, Manufacturing Inspection Branch, for coordination and approval, a detailed proposal regarding the procedure to be followed in establishing the system outlined in this section. Any proposal submitted by a manufacturer which can be shown to achieve the objective of the present requirements applying to weight and balance control; i. e., an accurate determination of average empty weight and empty c. g., will be considered acceptable.

(d) Example. The following example outlines an acceptable method for effecting this system:

(1) Actually weigh and determine empty c. g. of five to ten aircraft of a particular model, which have comparatively identical equipment installed, to determine the average weight and c. g.

(2) Weigh an individual aircraft at regular intervals; e. g., each tenth aircraft, as circumstances and conditions may warrant, for the purpose of determining continued accuracy of the initial empty weight and c. g. established.

(3) When the spot checking, as prescribed in subparagraph (2) of this paragraph indicates a variation in weight in excess of 1 percent of the initially established empty weight and/or a variation in the empty weight c. g. in excess of 1⁄2 percent of the MAC, a new average should be established in accordance with subparagraph (1) of this paragraph.

(4) Inasmuch as a weight and balance report is required in connection with each aircraft presented for certification, these reports may be computed for aircraft which are not actually weighed. Such reports should be marked "computed" for those aircraft which are not actually weighed, and other reports will be marked "actual."

[Supp. 5, 14 F. R. 5742, Sept. 20, 1949] § 3.73-2 Empty weight items (FAA interpretations which apply to § 3.73). (a) The empty weight must at least inIclude the items covered in § 3.73. Any additional items such as de-icer fluid, wash water and toilet chemical, if carried, should be included in the empty weight, or so handled that they will be

included in the useful load and takeoff weight.

(b) In any case, of course, the equipment list should clearly reflect which items are included in the empty weight. If this is done, it is not believed that confusion will result at some later date is to what is or is not added into the empty weight.

[Supp. 10, 16 F. R. 3283, Apr. 14, 1951] § 3.73-3 Unusable fuel supply and undrainable oil (FAA interpretations which apply to § 3.73).

(a) Unusable fuel is determined by the provisions of § 3.437. The unusable fuel, whether or not greater than 5 percent of the fuel tank capacity or one gallon (see §3.440) should be included in the empty weight. If the unusable fuel supply is greater than 5 percent or one gallon, the fuel quantity indicator should be marked in accordance with the provisions of § 3.761.

(b) Undrainable oil is defined as that oil which remains in the system after draining oil from all aircraft components including the engine by means of the oil drains provided, with the aircraft in ground attitude.

(c) All fuel and oil weight in the airplane that is not measureable by the gauges provided should be accounted for. preferably in inclusion in the empty weight.

[Supp. 10, 16 F. R. 3283, Apr. 14, 1951] § 3.74 Maximum weight.

(a) The maximum weight shall not exceed any of the following:

(1) The weight selected by the applicant.

(2) The design weight for which the structure has been proven, except as provided in § 3.242 for multiengine airplanes.

(3) The maximum weight at which compliance with all of the applicable flight requirements has been demonstrated.

(b) The maximum weight shall not be less than the weights under the loading conditions prescribed in subparagraphs (1) and (2) of this paragraph assuming that the weight of the occupant in each of the seats is 170 pounds for the normal category and 190 pounds for the utility and acrobatic categories. unless placarded otherwise.

(1) All seats occupied, oil to full tank capacity, and at least a fuel supply for one-half hour operation at rated maximum continuous power.

(2) Fuel and oil to full tank capacities, and minimum crew.

§ 3.75 Minimum weight.

The minimum weight shall not exceed the sum of the weights of the following: (a) The empty weight as defined by § 3.73.

(b) The minimum crew necessary to operate the airplane (170 pounds for each crew member).

(c) Fuel and oil quantities not greater than the minima specified in § 3.74 (b) (1).

[21 F.R. 3339, May 22, 1956, as amended by Amdt. 3-2, 22 F.R. 5561, July 16, 1957] § 3.76

Center of gravity position.

If the center of gravity position under any possible loading condition between the maximum weight as specified in § 3.74 and the minimum weight as specified in § 3.75 lies beyond (a) the extremes selected by the applicant, or (b) the extremes for which the structure has been proven, or (c) the extremes for which compliance with all functional requirements were demonstrated, loading instructions shall be provided in the Airplane Flight Manual as specified in § 3.777-3.780.

§ 3.76-1 Center of gravity position

(FAA policies which apply to § 3.76).

(a) It is suggested that as wide a range of c.g. as practicable be investigated (using ballast if necessary) in the flight tests to provide for future changes in empty weight c.g. without rerunning tests or structural analysis.

(b) Where practicable, the extreme c. g. positions should be investigated, both in structural design and flight tests in combination with maximum weight (using ballast if necessary) to make loading instructions as simple as possible, and also provide for future changes in empty weight c. g. and useful load.

(c) In cases where the permissible c. g. positions vary with maximum weight, it is suggested that a note be included in the loading instruction portion of the Airplane Flight Manual advising owners to contact the airplane manufacturer for new loading instructions when any change is made to the airplane which

The following items of performance shall be determined and the airplane shall comply with the corresponding requirements in standard atmosphere and still air.

§ 3.82 Definition of stalling speeds.

(a) V., denotes the true indicated stalling speed, if obtainable, 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),

(2) Propellors in 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) Vs1 denotes the true indicated stalling speed, if obtainable, otherwise the calculated value in miles per hour, with:

(1) Engines idling, throttles closed (or not more than sufficient power for zero thrust),

(2) Propellers in 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 V., 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.

(c) These speeds shall be determined by flight tests using the procedure outlined in § 3.120.

§ 3.82-1

"Zero thrust" (FAA interpretations which apply to § 3.82).

As used in § 3.82 (a) (1) and (b) (1) the term "zero thrust" contained in the phrase "engines idling, throttles closed (or not more than sufficient power for zero thrust)" is interpreted to permit "zero thrust at a speed not greater than 110 percent of the stalling speed." [Supp. 1, 12 F. R. 3434, May 28, 1947, as amended by Amdt. 1, 14 F. R. 36, Jan. 5, 1949] § 3.83 Stalling speed.

Vso at maximum weight shall not exceed 70 miles per hour for (1) singleengine airplanes and (2) multiengine airplanes which do not have the rate of climb with critical engine inoperative specified in § 3.85 (b).

TAKE-OFF

§ 3.84 Take-off.

(a) The distance required to take off and climb over a 50-foot obstacle shall be determined under the following conditions:

(1) Most unfavorable combination of weight and center of gravity location,

(2) Engines operating within the approved limitations,

(3) Cowl flaps in the position normally used for take-off.

(b) Upon obtaining a height of 50 feet above the level take-off surface, the airplane shall have attained a speed of not less than 1.3 V11 unless a lower speed of not less than Vr plus 5 can be shown to be safe under all conditions, including turbulence and complete engine failure.

(c) The distance so obtained, the type of surface from which made, and the pertinent information with respect to the cowl flap position, the use of flight-path control devices and landing gear retraction system shall be entered in the Airplane Flight Manual. The take-off shall be made in such a manner that its reproduction shall not require an exceptional degree of skill on the part of the pilot or exceptionally favorable conditions.

performance and to provide the Airplane Flight Manual performance data required in § 3.780 (a) (3) and (4), the following procedure may be used during official type tests:

(a) The ground and climb distances may be determined separately and the corrected data pieced together (as is now done in the transport category). Thus, for the simplest procedure, the airplane would be accelerated on (or near) the ground with gear extended to a speed not less than 1.3V11, and a climb segment to the 50-foot height point with gear extended would be determined by saw-tooth climb data. If it is desired to assume retraction of the landing gear at an earlier point, such point should be assumed to occur not earlier than that which would be used in normal take-offs. The acceleration to 1.3V, should then be measured as above, with gear retraction being initiated at the selected speed. If gear retraction is completed before reaching 1.3V11, only one climb segment, with gear retracted, need be determined. If retraction is not completed during acceleration to 1.3V,,, two climb segments should be determined; one with gear extended for the time period necessary to complete retraction; the second with gear retracted. The acceleration segment should be determined photographically, and a minimum of three trials should be made up to speeds equal to or greater than 1.3V..

NOTE: (FAA camera equipment may be obtained on a loan basis).

(b) Based upon the FAA's experience to date, the test method outlined in paragraph (a) of this section has given the desired accuracy of results. It also provides suitable means for showing the approximate calculated effect of temperature and altitude upon climb (up to 7,000 feet).

NOTE: It is permissible for other methods to be used in accomplishing these tests, providing that any method used is one which the average pilot may be reasonably expected to duplicate without use of unusual skill or experience, and one which produces equivalent accuracy. The operating procedure which must be followed to achieve the measured performance should in all cases described in the Airplane Flight Manual.

be

(c) The take-off and climb requirements of §§ 3.84 and 3.85 were written to assure the airplane's ability to clear obstacles in the vicinity of the airport. Consequently, the wing flap used for the