3. In determining the maximum certificated weight the structural soundness of the airplane and the terrain to be traversed in the operation will be considered.

4. The maximum certificated weight so determined will be added to the airplane's operation limitations and identified as the maximum weight authorized for operations within the State of Alaska.

This regulation supersedes Special Civil Air Regulation No. SR-399C, and shall terminate on October 25, 1965, unless sooner superseded or rescinded.

(Secs. 313(a), 601, 603, 604; 72 Stat. 752, 775, 776, 778; 49 U.S.C. 1354, 1421, 1423, 1424) [26 F.R. 5673, June 24, 1961]

SR-411A

Notwithstanding the applicable structural provisions of the Civil Air Regulations, any air carrier may operate in cargo service transport category airplanes which were certificated under the provisions of Part 4a or Part 4b, effective prior to March 13, 1956, subject to the conditions hereinafter set forth:

(1) The air carrier shall submit an application to the Administrator indicating its desire to operate its airplane(s) under the provisions of this special regulation, and indicating which airplane(s) would be involved.

(2) The air carrier shall furnish a statement from each manufacturer for each type of airplane involved indicating in each case that the airplane manufacturer approves the operation of such type of airplane under the provisions of this regulation and that the airplane manufacturer will establish the inspection procedure prescribed in paragraph (4) of this Special Civil Air Regulation and will supervise such inspection as necessary.

(3) The zero fuel weight (maximum weight of the airplane with no disposable fuel and oil) and the structural landing weight may be increased beyond the maxima approved in full compliance with the applicable Civil Air Regulations: Provided, That the Administrator of Civil Aeronautics finds that the increase in either such weight is not likely to reduce seriously the structural strength, that the probability of sudden fatigue failure is not noticeably increased, and that the flutter, deformation, and vibration characteristics do not fall below those required by the Civil Air Regulations: And provided further, That any increase in the zero fuel weight approved shall not exceed 5 percent and that the increase in the structural landing weight shall not exceed the amount, in pounds, of the increase in the zero fuel weight.

(4) Airplanes for which the increased weights become effective shall be subject to inspections in addition to those normally performed, such inspections to be established by the manufacturer of the type airplane concerned, subject to the approval of the Administrator of the Federal Aviation Agency and to be supervised as found neces

sary by that manufacturer, to safeguard against possible structural distress resulting from the higher operating stress levels. The air carrier shall keep for a period of at least one year, and make available upon request to the Civil Aeronautics Board, the Administrator of the Federal Aviation Agency, or the manufacturer of the type of airplane concerned, the records of such inspections.

(5) Airplanes for which the increased weights become effective shall be operated in accordance with the transport category performance operating limitations prescribed in Part 40, 41, or 42 of the Civil Air Regulations, whichever is applicable.

(6) The air carrier shall keep for a period of at least one year and make available upon request to the Civil Aeronautics Board, the Administrator of the Federal Aviation Agency, or the manufacturer of the type airplane concerned, records of all flights conducted at increased weights with airplanes for which the increased weights become effective, such records to include the actual take-off, zero fuel, and landing weights.

(7) The Airplane Flight Manual of each airplane operating under the provisions of this special regulation shall be appropriately revised so as to include the necessary operating limitations and operating information.

(8) An airplane which has been operated at increased weights under the provisions of this regulation shall not be used for the carriage of passengers, except under the following conditions:

(a) Special inspections established by the manufacturer and approved by the Administrator of the Federal Aviation Agency shall have been accomplished.

(b) The effects of the operations at increased weights on structural fatigue shall have been evaluated by the airplane manufacturer and taken into account in any fatigue limitations established for the airplane.

This regulation shall terminate on June 30, 1962, unless sooner superseded or rescinded by the Board.

[22 F. R. 4685, July 3, 1957]

CROSS REFERENCES: For Special Civil Air Regulation with respect to establishing the basis for approval by the Administrator of modifications of individual DC-3 and L-18 airplanes, see SR-407 in Part 1 of this subchapter.

For Special Civil Air Regulation with respect to performance credit for use of standby power on transport category airplanes, see SR 426 in Part 1 of this subchapter.

Subpart A-Airworthiness
Requirements

SOURCE: §§ 4a.1 to 4a.31-1 contained in Amendment 48, 5 F. R. 1834, May 22, 1940, as amended by Amendment 75, 5 F. R. 3946, Oct. 8, 1940; 24 F.R. 5, Jan. 1, 1959, except as otherwise noted.

§ 4a.1 Scope.

GENERAL

The airworthiness requirements set forth in this part shall be used as a basis for obtaining airworthiness or type certificates: Provided, That: (a) Deviations from the requirements of this part which, in the opinion of the Administrator, insure the equivalent condition for safe operation and, (b) equivalent requirements of the United States Army or Navy with respect to airworthiness may be accepted in lieu of the requirements set forth in this part. Unless

otherwise specified an amendment to this part will apply only to airplanes for which applications for type certificates are received subsequent to the effective date of such amendment.

§ 4a.2 Airplane categories.

(a) At the election of the applicant, an airplane may be certificated under the requirements for a particular category according to the intended use of the airplane. Sections of this part which affect only one particular category are designated by a suffix added to the appropriate section numbers, as follows:

(b) All sections not designated by a suffix are applicable to all categories, except as otherwise specified. [Amdt. 04-3, 7 F. R. 984, Feb. 14, 1942] AIRWORTHINESS AND TYPE CERTIFICATES

§ 4a.15 Requirements for issuance.

The airworthiness requirements specified in this part shall be used as a basis for the certification of airplanes: Provided, That an airplane manufactured in accordance with, and conforming to, the currently effective aircraft specifications issued therefor will be eligible for an airworthiness certificate, if the Administrator determines such airplane is in condition for safe operation: Provided, further, That an airplane which has not demonstrated compliance with the airworthiness requirements specified in this part but which, in the opinion of the Administrator, is in condition for safe operation for experimental purposes or for particular activities will be eligible for an airworthiness certificate.

Authorized representatives of the Administrator shall have access to the airplane and may witness or conduct such inspections and tests as are deemed necessary by the Administrator.

[Amdt. 48, 5 F. R. 1834, May 22, 1940, as amended by Amdt. 04a-6, 12 F. R. 1029, Feb. 13, 1947]

§ 4a.19 Flight tests.

(Applicable to all airplanes certificated as a type on or after May 15, 1947.) After proof of compliance with the structural requirements contained in this part, and upon completion of all necessary inspection and testing on the ground, and proof of the conformity of the airplane with the type design, and upon receipt from the applicant of a report of flight tests conducted by him, there shall be conducted such official flight tests as the Administrator finds necessary to determine compliance with Subparts C-G. After the conclusion of these flight tests such additional flight tests shall be conducted as the Administrator finds necessary to ascertain whether there is reasonable assurance that the airplane, its components, and equipment are reliable and function properly. The extent of such additional flight tests shall depend upon the complexity of the airplane, the number and nature of new design features, and the record of previous tests and experience for the particular airplane model, its

components, and equipment. If practicable, the flight tests performed for the purpose of ascertaining the reliability and proper functioning shall be conducted on the same airplane which was used in flight tests to show compliance with Subparts C-G.

[Amdt. 04a-6, 12 F. R. 1029, Feb. 13, 1947, as amended by Amdt. 04a-7, 12 F. R. 2087, Mar. 29, 1947]

§ 4a.20 Procedure for type certification.

Acceptable procedures for type certification are outlined in Civil Aeronautics Manual 4.

CHANGES

§ 4a.25 Continued compliance.

Changes to certificated aircraft shall be substantiated to demonstrate continued compliance of the aircraft with the pertinent airworthiness requirements.

§ 4a.26 Minor changes.

Minor changes to airplanes being manufactured under the terms of a type certificate and which obviously do not impair the condition of the airplane for safe operation may be approved by authorized representatives of the Administrator prior to submittal to the Administrator of any required revised drawings. The approval of such minor changes shall be based on the airworthiness requirements in effect when the particular airplane model was originally certificated, unless, in the opinion of the Administrator, compliance with current airworthiness requirements is necessary. § 4a.27 Major changes.

Major changes to airplanes being manufactured under the terms of a type certificate may require the issuance of a new type certificate and the Administrator may, in his discretion, require such changes to comply with current airworthiness requirements.

§ 4a.28 Changes required by the Administrator.

(a) In the case of aircraft models approved under the airworthiness requirements in effect prior to the currently effective regulations, the Administrator may require that aircraft submitted for original airworthiness certification comply with such portions of the currently effective regulations as are considered necessary.

(b) All aircraft certificated under the transport category, the manufacture of which is completed after September 30, 1947, shall comply with the following sections of Part 4b of this subchapter, as amended: §§ 4b.58, 4b.442, 4b.445 (a), 4b.447, 4b.478, 4b.484, 4b.503 (c), 4b.5164b.518, 4b.556, 4b.557, 4b.560, 4b.561, 4b.586, 4b.621-4b.624, 4b.651-4b.655, 4b.661-4b.676 (14 F. R. 4102, July 16, 1949).

[Amdt. 48, 5 F. R. 1834, May 22, 1940, as amended by Amdt. 04-4, 11 F. R. 11353, Oct. 4, 1946; Amdt. 04a-8, 12 F. R. 5959, Sept. 9, 1947]

APPROVAL OF MATERIALS, PARTS, PROCESSES, AND APPLIANCES Specifications.

§ 4a.31

(a) Materials, parts, processes, and appliances shall be approved upon a basis and in a manner found necessary by the Administrator to implement the pertinent provisions of the regulations in this subchapter. The Administrator may adopt and publish such specifications as he finds necessary to administer this section, and shall incorporate therein such portions of the aviation industry, Federal, and military specifications respecting such materials, parts, processes, and appliances as he finds appropriate.

(b) Any material, part, process, or appliance shall be deemed to have met the requirements for approval when it meets the pertinent specifications adopted by the Administrator, and the manufacturer so certifies in a manner prescribed by the Administrator.

[Amdt. 04a-1, 12 F. R. 7898, Nov. 25, 1947] § 4a.31-1 Approval of aircraft components (FAA rules which apply to § 4a.31).

Aircraft components made the subject of Technical Standard Orders shall be approved upon the basis and in the manner provided in Part 514 of this title. [Supp. 9, 16 F. R. 671, Jan. 25, 1951]

Subpart B-Definitions

SOURCE: §§ 4a.37 to 4a.46 contained in Civil Air Regulations, May 31, 1938, as amended by Amendment 75, 5 F. R. 3946, Oct. 8, 1940, except as otherwise noted.

§ 4a.37 Weights.

(a) Weight, W. The total weight of the airplane and its contents.

(b) Design weight. The weight of the airplane assumed for purposes of show

ing compliance with the structural requirements specified in this part.

Weight

(c) Minimum design weight. empty with standard equipment, plus crew, plus fuel of 0.25 pound per maximum (except take-off) horsepower, plus oil as per capacity.

(d) Standard weight. The maximum weight for which the airplane is certificated as complying with all the airworthiness requirements for normal operations.

(e) Provisional weight. The maximum weight for which the airplane is certificated as complying with the airworthiness requirements as modified for scheduled air carriers in §§ 4a.687. [CAR, May 31, 1938, as amended at 15 F. R. 5069, Aug. 8, 1950]

The area

(a) Design wing area, S. enclosed by the projection of the wing outline, including ailerons and flaps but ignoring fairings and fillets, on a surface containing the wing chords. The outline is assumed to extend through nacelles and through the fuselage to the plane of symmetry.

(b) Design power, P. The total engine horsepower chosen for use in determining the maneuvering load factors. The corresponding engine output will be incorporated in the aircraft certificate as a maximum operational limitation in all flight operations other than take-off or climbing flight (see § 4a.727).

The

(c) Design wing loading, W/S. design weight (§ 4a.37 (b)) divided by the design wing area (paragraph (a) of this section).

(d) Design power loading, W/P. The design weight (§ 4a.37 (b)) divided by the design power (see paragraph (b) of this section and Fig. 4a-3).

[CAR, May 31, 1938, as amended by Amdt. 5, 4 F. R. 1171, Mar. 9, 1939]

§ 4a.39 Air density, p.

The mass density of the air through which the airplane is moving, in terms of the weight of a unit volume of air divided by the acceleration of gravity. The symbol po denotes the mass density of air at sea level under standard atmospheric conditions and has the value of 0.002378 slugs per cubic foot.

CROSS REFERENCE: For definition of standard atmosphere, see § 4a.45.

§ 4a.40 Speed.

(a) True air speed, Vt. The velocity of the airplane, along its flight path, with respect to the body of air through which the airplane is moving.

(b) Indicated air speed, V. The true air speed multiplied by the term Vp/Po (See § 4a.39.)

(c) Design level speed, VL. The indicated air speed chosen for use in determining the pertinent structural loading conditions. This value will be incorporated in the aircraft certificate as a maximum operational limitation in level and climbing flight (see § 4a.726).

(d) Design gliding speed, V,. The maximum indicated air speed to be used in determining the pertinent structural loading conditions (see §§ 4a.73 and 4a.726).

(e) Design stalling speed, Vs. The computed indicated air speed in unaccelerated flight based on the maximum lift coefficient of the wing and the design gross weight. The effects of slipstreams and nacelles shall be neglected in computing Vs. When high-lift devices are in operation the corresponding stalling speed will be denoted by Vst.

(f) Design flap speed, Vt. The indicated air speed at which maximum operation of high-lift devices is assumed (see §§ 4a.73 and 4a.726).

(g) Maximum vertical speed, Vm. A fictitious value of indicated air speed computed for unaccelerated flight in a vertical dive with zero propeller thrust.

(h) Design maneuvering speed, Vp. The indicated air speed at which maximum operation of the control surfaces is assumed (see § 4a.73).

[CAR, May 31, 1938, as amended by Amdt. 5, 4 F. R. 1171, Mar. 9, 1939]

§ 4a.41 Design gust velocity, U.

(a) Load factor or acceleration factor, n. The ratio of a load to the design weight. When the load in question represents the net external load acting on the airplane in a given direction, n represents the acceleration factor in that direction.

(b) Limit load. A load (or load factor, or pressure) which it is assumed or known may be safely experienced but will not be exceeded in operation.

(c) Factor of safety, j. A factor by which the limit loads are multiplied for various design purposes.

(d) Ultimate factor of safety, ju. A specified factor of safety used in determining the maximum load which the airplane structure is required to support.

(e) Yield factor of safety, jy. A specified factor of safety used in connection with the prevention of permanent deformations.

(f) Ultimate load. A limit load multiplied by the specified ultimate factor (or factors) of safety. (See definitions in this section and § 4a.61.)

(g) Yield load. A limit load multiplied by the specified yield factor (or factors) of safety. (See definitions in this section and § 4a.62.)

(h) Strength test. A static load test in which the ultimate loads are properly applied. (See §§ 4a.61 and 4a.230 (b).)

(i) Proof test. A static load test in which the yield loads are properly applied for a period of at least 1 minute. (See § 4a.62.)

(j) Balancing loads. Loads by which the airplane is placed in a state of equilibrium under the action of external forces resulting from specified loading conditions. The state of equilibrium thus obtained may be either real or fictitious. Balancing loads may represent air loads, inertia loads, or both. (See § 4a.116.)

§ 4a.44 Aerodynamic coefficients, CL, CM, CP, etc.

The coefficients hereinafter specified are those of the "absolute" (nondimensional) system adopted as standard in the United States. The subscripts N and C used hereinafter refer respectively to directions normal to and parallel with the basic chord of the airfoil section. Other subscripts have the usual significance. When applied to an entire wing or surface, the coefficients represent

average values and shall be properly correlated with local conditions (load distribution) as required in § 4a.99. § 4a.45 air).

Standard atmosphere (standard

Standard atmosphere refers to that variation of air conditions with altitude which has been adopted as standard in the United States. (See any areonautics text book or handbook, or NACA Technical Report No. 218.)

§ 4a.46 Primary structure.

Those portions of the airplane the failure of which would seriously endanger the safety of the airplane. [Amdt. 5, 4 F. R. 1171, Mar. 9, 1939]

Subpart C-Structural Loading
Conditions

SOURCE: $§ 4a.61 to 4a.216 contained in Civil Air Regulations, May 31, 1938, as amended by Amdt. 75, 5 F. R. 3946, Oct. 8, 1940, except as otherwise noted.

GENERAL STRUCTURAL REQUIREMENTS § 4a.61

Strength.

The primary structure shall be capable of supporting without detrimental permanent deformations, for a period of alt least one minute, the yield loads (see § 4a.43(g)) determined by the loading conditions and yield factors of safety specified in this part, the loads being properly distributed and applied. Where no yield factor of safety is specified a factor of 1.0 shall be assumed. In addition, temporary deformations which occur before the yield load is reached shall be of such a nature that their repeated occurrence will not weaken or damage the primary structure.