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Tests in environments such as sand and dust, fungus and saltspray may be limited to equipment likely to be exposed to these conditions.

(c) Electrical equipment altitude testing should be conducted at an altitude 15 percent above the maximum altitude to which the equipment would be exposed in normal service. However, testing of certain equipment installed in pressurized areas should be under conditions of altitude and time which will assure that, in case of rapid decompression:

(1) Equipment necessary for the execution of an emergency descent would remain operative for the probable period required for such descent.

(2) Other equipment is not rendered permanently inoperative if the operation of the equipment is necessary to maintain controlled flight or effect a safe landing.

(3) No equipment will constitute a hazard due to arcing, fire, or smoke. However, altitude testing for hazard from arcing, fire, or smoke is not required where any hazard is satisfactorily minimized independently of altitude by design and installation features. [Supp. 41, 23 F. R. 10325, Dec. 25, 1958]

§ 4b.626 Electrical system fire and smoke protection.

The design and installation of all components of the electrical system shall be in compliance with pertinent fire and smoke protection provisions of §§ 4b.371 (c), 4b.385, and 4b.490. In addition, all electrical cables, terminals, and equipment which are necessary in emergency procedures and which are located in designated fire zones shall be fireresistant.

[Amdt. 4b-6, 17 F. R. 1098, Feb. 5, 1952] § 4b.626-1 Fire resistant electrical equipment (FAA policies which apply to § 4b.626).

When applied to the electrical equipment and components defined in the last

This policy establishes a basic test standard for fire resistant electrical equipment located in designated fire zones. However, installation approval may be granted for equipment which does not conform to this standard, if it can be shown that such equipment would provide equivalent safety if exposed to the probable fire conditions at its particular location.

sentence of § 4b.626, an accepted criterion for "fire resistant" is that such equipment and components, as installed in the aircraft, should withstand a 2,000° F. oxidizing flame impinging on their surfaces for at least five minutes without adverse effect on their circuit function.1o The 2,000° F. oxidizing flame should envelop the equipment under test, using a test setup simulating the actual aircraft installation." Thermocouples for measurement of flame temperature should be located within one-fourth inch of the surface exposed to the flame.

[Supp. 37, 23 F.R. 2790, Apr. 26, 1958] § 4b.627 Electrical

analyses.

system tests and

It shall be demonstrated by tests and analyses that the electrical system functions properly and without electrical or thermal distress.

[Amdt. 4b-6, 17 F. R. 1098, Feb. 5, 1952] § 4b.628 Lightning strike protection.

Those portions of the airplane which are electrically insulated from the main body of the airplane shall be connected to the basic airframe through appropriate lightning arrestors, unless it is shown that a lightning strike on the insulated portion is improbable because of the shielding afforded by other portions of the airplane, or unless it is shown that a lightning strike on the insulated portion would not create a hazard to the airplane or its occupants.

[Amdt. 4b-11, 24 F.R. 7071, Sept. 1, 1959]

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(c) A means of controlling the intensity of illumination shall be provided, unless it is shown that non-dimmed instrument lights are satisfactory under all expected conditions of flight.

§ 4b.631 Landing lights.

(a) Landing lights shall be of an approved type.

(b) Landing lights shall be installed so that there is no objectionable glare visible to the pilot and so that the pilot is not adversely affected by halation.

(c) Landing lights shall be installed in a location where they provide the necessary illumination for night landing.

(d) A switch for each light shall be provided, except that where multiple lights are installed at one location a single switch for the multiple lights shall be acceptable.

(e) A means shall be provided to indicate to the pilots when the landing lights are extended.

[15 FR. 3543, June 8, 1950, as amended by Amdt. 4b-6, 22 F.R. 5566, July 6, 1957]

§ 4b.632 Position light system installation.

(a) General. The provisions of §§ 4b.632 through 4b.635 shall be applicable to the position light system as a whole. The position light system shall include the items specified in paragraphs (b) through (d) of this section.

(b) Forward position lights. Forward position lights shall consist of a red and a green light spaced laterally as far apart as practicable and installed forward on an airplane in such a location that, with the airplane in normal flying position, the red light is displayed on the left side and the green light is displayed on the right side. The individual lights shall be of an approved type.

(c) Rear position light. The rear position light shall consist of a white light mounted on the airplane as far aft as practicable. The light shall be of an approved type.

(d) Light covers and color filters. Light covers or color filters used shall be of flame-resistant material and shall be constructed so that they will not change color or shape or suffer any appreciable loss of light transmission during normal use.

[Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950, as amended by Amdt. 4b-7, 17 F. R. 11631, Dec.

20, 1952; Amdt. 4b-8, 18 F. R. 2216, Apr. 18, 1953; Amdt. 4b-2, 20 F.R. 5308, July 26, 1955; Amdt. 4b-4, 22 F.R. 1274, Mar. 1, 1957; Amdt. 4b-11, 24 F.R. 7071, Sept. 1, 1959] § 4b.632-1

Red passing lights (FAA policies which apply to § 4b.632(a)).

When it is desired to improve the conspicuity of the aircraft, a steady red light, commonly known as a passing light, may be installed. This light is not considered to be a position light and therefore need not be type certificated. When installed, its location should be one of the following:

(a) Within the left landing light unit. (b) On the centerline of the aircraft nose.

(c) In the leading edge of the left wing, outboard of the propeller disc. [Supp. 17, 16 F. R. 3212, Apr. 12, 1951]

§ 4b.633 Position light system dihedral angles.

The forward and rear position lights as installed on the airplane shall show unbroken light within dihedral angles specified in paragraphs (a) through (c) of this section.

(a) Dihedral angle L (left) shall be considered formed by two intersecting vertical planes, one parallel to the longitudinal axis of the airplane and the other at 110° to the left of the first, when looking forward along the longitudinal axis.

(b) Dihedral angle R (right) shall be considered formed by two intersecting vertical planes, one parallel to the longitudinal axis of the airplane and the other at 110° to the right of the first, when looking forward along the longitudinal axis.

(c) Dihedral angle A (aft) shall be considered formed by two intersecting vertical planes making angles of 70° to the right and 70° to the left, respectively, looking aft along the longitudinal axis, to a vertical plane passing through the longitudinal axis.

[Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950] § 4b.634 Position light distribution and

intensities.

(a) General. The intensities prescribed in this section are those to be provided by new equipment with all light covers and color filters in place. Intensities shall be determined with the

light source operating at a steady value equal to the average luminous output of the light source at the normal operating voltage of the airplane. The light distribution and intensities of position lights shall comply with the provisions of paragraphs (b) and (c) of this section. (b) Forward and rear position lights. The light distribution and intensities of forward and rear position lights shall be expressed in terms of minimum intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum intensities in overlappng beams, within dihedral angles L, R, and A, and shall comply with the provisions of subparagraphs (1) through (3) of this paragraph.

(1) Intensities in horizontal plane. The intensities in the horizontal plane shall not be less than the values given in figure 4b-18. (The horizontal plane is the plane containing the longitudinal axis of the airplane and is perpendicular to the plane of symmetry of the airplane.)

(2) Intensities above and below horizontal. The intensities in any vertical plane shall not be less than the appropriate value given in figure 4b-19, where I is the minimum intensity prescribed in figure 4b-18 for the corresponding angles in the horizontal plane. (Vertical planes are planes perpendicular to the horizontal plane.)

(3) Overlaps between adjacent signals. The intensities in overlaps between adjacent signals shall not exceed the values given in Figure 4b-20, except that higher intensities in the overlaps shall be acceptable with the use of main beam intensities substantially greater than the minima specified in Figures 4b18 and 4b-19 if the overlap intensities in relation to the main beam intensities are such as not to affect adversely signal clarity.

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NOTE: Area A includes all directions in the adjacent dihedral angle which pass through the light source and which intersect the common boundary plane at more than 10 degrees but less than 20 degrees. Area B includes all directions in the adjacent dihedral angle which pass through the light source and which intersect the common boundary plane at more than 20 degrees.

FIGURE 4b-20-MAXIMUM INTENSITIES IN OVERLAPPING BEAMS OF FORWARD AND REAR POSITION LIGHTS [Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950, as amended by Amdt. 4b-2, 20 F. R. 5309, July 26, 1955; Amdt. 4b-4, 22 F.R. 1274, Mar. 1, 1957]

§ 4b.634-1 Overlaps between high intensity forward position lights (FAA policies which apply to § 4b.634 (b) (3)).

When the peak intensity of the forward position lights is greater than 100 candles, the maximum overlap intensities between them may exceed the values given in Figure 4b-20 provided the overlap intensity in Area A is not greater than 10 percent of peak position light intensity and the overlap intensity in Area B is not greater than 2.5 percent of peak position light intensity."

[Supp. 37, 23 F. R. 2790, Apr. 26, 1958]

12 Overlap intensities should be determined with the position lights installed in their actual airplane locations, since adjacent airplane structure will often provide some cutoff in the overlap area.

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(a) Aviation red.

y is not greater than 0.335,

z is not greater than 0.002;

(b) Aviation green.

z is not greater than 0.440-0.820y,
z is not greater than y―0.170,

y is not less than 0.890-0.170x;

(c) Aviation white.

1 not less than 0.350.

z is not greater than 0.540,

y-yo is not numerically greater than 0.01, yo being the y coordinate of the Planckian radiator for which o=1.

[Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950]

§ 4b.636 Riding light.

(a) When a riding (anchor) light is required for a seaplane, flying boat, or amphibian, it shall be capable of showing a white light for at least two miles at night under clear atmospheric conditions.

(b) The riding light shall be installed to show the maximum unbroken light practicable when the airplane is moored or drifting on the water. Externally hung lights shall be acceptable. [15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950] § 4b.637 Anti-collision light system.

An anti-collision light system shall be installed which shall consist of one or more approved anti-collision lights so located that the emitted light will not be detrimental to the crew's vision and will not detract from the conspicuity of the position lights. The system shall comply with the provisions of paragraphs (a) through (d) of this section.

(a) Field of coverage. The system shall consist of such lights as will afford coverage of all vital areas around the airplane with due consideration to the physical configuration and the flight characteristics of the airplane. In any case, the field of coverage shall extend in all directions within 30° above and 30° below the horizontal plane of the airplane, except that a solid angle or angles of obstructed visibility totaling not more than 0.03 steradians shall be permissible within a solid angle equal to 0.15 steradi

ans centered about the longitudinal axis in the rearward direction.

(b) Flashing characteristics. The arrangement of the system, i. e., number of light sources, beam width, speed of rotation, etc., shall be such as to give an effective flash frequency of not less than 40 and not more than 100 cycles per minute. The effective flash frequency shall be the frequency at which the airplane's complete anti-collision light system is observed from a distance, and shall apply to all sectors of light including the overlaps which might exist when the system consists of more than one light In overlaps, flash frequencies higher than 100 cycles per minute shall be permissible, except that they shall not be higher than 180 cycles per minute.

source.

(c) Color. The color of the anti-collision lights shall be aviation red in accordance with the specifications of § 4b.635 (a).

(d) Light intensity. The minimum light intensities in all vertical planes, measured with the red filter and expressed in terms of "effective" intensities, shall be in accordance with Figure 4b-27. The following relation shall be sumed:

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in icing conditions. When compliance is shown with the provisions of this section, the type certificate shall include certification to that effect. When an airplane is certificated to include ice protection provisions, the recommended procedures for the use of the ice protection equipment shall be set forth in the Airplane Flight Manual (see § 4b.742 (a)). It shall be shown, as prescribed in paragraphs (a) and (b) of this section, that the airplane is capable of operating safely in continuous maximum and intermittent maximum icing conditions as defined in §§ 4b.1(b) (7) and (8).

(a) An analysis shall be performed to establish, on the basis of the airplane's operational needs, the adequacy of the ice protection system for the various components of the airplane.

(b) In addition to the analysis and physical evaluation prescribed in paragraph (a) of this section, the effectiveness of the ice protection system and its components shall be shown by one or more of the following means:

(1) Laboratory dry air and/or simulated icing tests of the actual components or models thereof.

(2) Flight dry air tests of the ice protection system as a whole, or of its components individually.

(3) Flight tests of the airplane or its components in measured simulated icing conditions.

(4) Flight tests of the airplane in measured natural atmospheric icing conditions.

NOTE: For turbine-powered airplanes, the ice protection provisions of this section are considered to be primarily applicable to the airframe. For the powerplant installation, certain additional provisions of Subpart E of this part may be found applicable.

[Amdt. 4b-2, 20 F.R. 5309, July 26, 1955, as amended by Amdt. 4b-6, 22 F.R. 5566, July 16, 1957]

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(c) If recoil loads are involved in the ejection of the flares, the structure of the airplane shall withstand such loads.

§ 4b.642-1

Procedure for testing flare ejection (FAA policies which apply to § 4b.642(b)).

When flares are released, they should clear the aircraft structure when the airplane is flown at a speed of 1.4 V., with the wing flaps and landing gear in both extended and retracted positions. If it is obvious that the flaps and gear have no effect upon the flare's path, the test may be conducted at one configuration. It is permissible to use dummy flares with parachutes for this test. [Supp. 24, 19 F. R. 4466, July 20, 1954]

§ 4b.643 Safety belts.

or

Safety belts shall be of an approved type. In no case shall the rated strength of the safety belt be less than that corresponding with the ultimate load factors specified in § 4b.260 (a), taking due account of the dimensional characteristics of the safety belt installation for the specific seat berth arrangement. Safety belts shall be attached so that no part of the anchorage will fail at a load lower than that corresponding with the ultimate load factors equal to those specified in § 4b.260 (a) multiplied by a factor of 1.33. In the case of safety belts for berths, the forward load factor need not be applied.

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-8, 18 F. R. 2216, Apr. 18, 1953; Amdt. 4b-2, 20 F. R. 5309, July 26, 1955; Amdt. 4b-3, 21 F. R. 994, Feb. 11, 1956]

§ 4b.644 Safety belt signal.

When means are provided to indicate to the passengers when seat belts should be fastened, the device shall be so installed that it can be operated from the seat of either pilot or copilot.

§ 4b.645 Ditching equipment.

When the airplane is certificated for ditching in accordance with § 4b.361, and when required by the operating rules for the particular route to be flown, the ditching equipment shall be as prescribed in paragraphs (a) through (d) of this section.

(a) Life rafts. Life rafts shall be of an approved type. Unless excess rafts of sufficient capacity are provided, the buoyancy and seating capacity beyond the rated capacity of the rafts shall be such as to accommodate all occupants

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