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(c) Methods of identifying products approved under this section. (1) Products approved as a part of the airplane type design under a type certificate should be identified by an airplane part number on the approved drawing list..

(2) Products approved as a part of the airplane type design under a supplemental type certificate should be identified by a part or drawing number on such certificate.

(3) Each TSO product that is approved as a part of the airplane should have the TSo identification removed and be identified as set forth in subparagraph (1) or (2) of this paragraph, whichever is applicable. [Supp. 34, 23 F.R. 10324, Dec. 25, 1958] $ 3.19 Changes in type design.

(For requirements with regard to changes in type design and the designation of applicable regulations therefor, see § 3.11 (d) and (e), and Part 1 of this subchapter.) $ 3.19-1 Changes of engines (FAA pol

icies which apply to $ 3.19). (a) There are currently available newly designed engines of approximately the same size and weight as previously designed engines, but with considerable variations in power. It is possible to inerchange these engines with little or no installation changes, and although minor changes in engine weight may be Involved, it will still be practical to operate the aircraft at the originally approved gross weight. Under $ 3.185, the naneuvering load factor is not dependint upon engine power, and under $ 3.184 he design airspeeds can be independent of engine power. Therefore, a change vhich involves or permits a practical power increase by exchange of engines hall be approved by the Administrator: Provided, That such exchange of engines s not accompanied by an increase in he gross weight of the aircraft, or an ncrease in placard speeds. Under those onditions it will not be necessary to estrict the maximum continuous horselower by a placard because of the airlane speed limitations since the latter re indicated on the speed placards.

(b) Aircraft alterations involving reight or speed changes beyond those set

forth above will be approved by the Administrator, if the applicant shows compliance with the applicable airworthi. ness requirements.

(c) Under $ 3.19, it will be necessary to require such investigations of local structure, weight and balance, power plant installations and flight tests as are normally involved in a change of engine type. However, every effort will be made by reference to data already on hand to minimize the amount of testing and structural analysis required of the applicant. [Supp. 10, 16 F. R. 3281, Apr. 1951, as amended by Supp. 14, 17 F. R. 9065, Oct. 11, 1952)

AIRPLANE CATEGORIES $ 3.20 Airplane categories.

(a) For the purpose of certification under this part, airplanes are divided upon the basis of their intended operation into the following categories:

(1) Normal-suffix N. Airplanes in this category are intended for nonacrobatic, nonscheduled passenger, and nonscheduled cargo operation.

(2) Utility-suffix U. Airplanes in this category are intended for normal operations and limited acrobatic maneuvers. These airplanes are not suited for use in snap or inverted maneuvers.

NOTE: The following interpretation of paragraph (a) (2) was issued May 15, 1947, 12 F. R. 3434: The phrase "limited acrobatic maneuvers" as used in $ 3.6 (now $ 3.20) 18 Interpreted to include steep turns, spins, stalls (except whip stalls), lazy eights, and chandelles.

(3) Acrobatic-suffix A. Airplanes in this category will have no specific restrictions as to type of maneuver permitted unless the necessity therefor is disclosed by the required flight tests.

(b) An airplane may be certificated under the requirements of a particular category, or in more than one category, provided that all of the requirements of each such category are met. Sections of this part which apply to only one or more, but not categories are identified in this part by the appropriate suffixes added to the section number, as indicated in paragraph (a) of this section. All sections not identified by a

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

sufix are applicable to all categories except as otherwise specified. § 3.20–1 Approved maneuvers for nor

mal category aircraft (FAA interpre

tations which apply to 8 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)

ments.

Official type tests will be discontinued until corrective measures have been taken by the applicant when either:

(a) The applicant's test pilot is unable or unwilling to conduct any of the required flight tests; or

(b) Items of noncompliance with requirements are found which may render additional test data meaningless or are of such nature as to make further testing unduly hazardous. $ 3.64 Emergency egress.

Adequate provisions shall be made for emergency egress and use of parachutes by members of the crew during the flight tests. $ 3.65 Report.

The applicant shall submit to the representative of the Administrator & report covering all computations and tests required in connection with calibration of instruments used for test purposes and correction of test results to standard atmospheric conditions. The representative of the Administrator will conduct any flight tests which he finds to be necessary in order to check the calibration and correction report. WEIGHT RANGE AND CENTER OF GRAVITY $ 3.71 Weight and balance.

(a) There shall be established, as & part of the type inspection, ranges of weight and center of gravity within

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

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:

Tolerance Item

(percent) General.

+5; -10. Flight characteristics, general.-- +5; – 10. Flight characteristics, critical items affected by weight.------- +6; -1.

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

(c) The airplane certificated weight and center of gravity range should not exceed the authorized structural limits. (Supp. 10, 16 F.R. 3282, Apr. 14, 1951, as amended by Supp. 14, 17 F.R. 9066, Oct. 11, 1952; Supp. 26, 22 F.R. 1025, Feb. 20, 1957] $ 3.72 Use of ballast.

Removable ballast may be used to enable airplanes to comply with the flight requirements in accordance with the following provisions:

(a) The place or places for carrying ballast shall be properly designed, installed, and plainly marked as specified in $ 3.766.

(b) The Airplane Flight Manual shall include instructions regarding the proper disposition of the removable ballast under all loading conditions for which such ballast is necessary, as specified in 88 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 accordance 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 dificulties 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) $ 3.73 Empty weight.

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 regard. ing 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 12 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. 6, 14 F. R. 5742, Sept. 20, 1949) $ 3.73–2 Empty weight items (FAA in

terpretations which apply to $ 3.73). (a) The empty weight must at least include 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 un

drainable 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

would appreciably affect the location of the empty weight c. g. or the useful load. [Supp. 10, 16 F. R. 3283, Apr. 14, 1951) PERFORMANCE REQUIREMENTS

PERFORMANCE $ 3.80

Alternate performance requirements. The provisions of $$ 3.84, 3.85, 3.86, and 3.112(a) (2) (ii) shall not be applicable to airplanes having a maximum certificated take-off weight of 6,000 pounds or less. In lieu thereof, such airplanes shall comply with the provisions of $ $ 3.84a, 3.85a, 3.87, and 3.112 (c). $ 3.81

Performance. 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 Vs, is being used as a factor to determine a required performance.

(b) Vs, 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 suficient 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 Vs, is being used.

(3) The weight of the airplane equal to the weight in connection with which

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