erating system, or in the generator drive system, should result in the permanent loss of service to electric utilization systems which are necessary to maintain controlled flight and to effect a safe landing, unless the aircraft is equipped with an independent source of electric power capable of supplying continuous emergency service to these utilization systems.

(c) Corrective action. Where corrective action is necessary to comply with paragraphs (a) and (b) of this section,

(1) Adequate warning should be provided for any malfunction or failure requiring such corrective action.

(2) Controls should be so located as to permit such corrective action during any probable flight situation.

(3) If corrective action must be taken within a specified time interval for continued safe operation of the generating system, it should be demonstrated that such corrective action can be accomplished within the specified time interval during any probable flight situation.

(4) The procedure to be followed by the crew should be detailed in the Operating Procedures Section of the Airplane Flight Manual (see § 4b.740).

(d) Electric system smoke and fire procedures (see § 4b.371 (c)). To cope with electrical smoke or fire of undetermined origin, generating system controls should be designed to permit electrical disconnection of overheated equipment in flight without hazardous interruption of service to electric utilization systems.

would not be detected during normal operation of the system, including periodic checks established at intervals which are consistent with the degree of hazard involved, or (2) the first malfunction would inevitably lead to other malfunctions.

The generator drive system includes the prime movers (propulsion engines or other) and coupling devices such as gear-boxes or constant-speed drives.

An electric utilization system is a system of electric equipment, devices and connected wiring which utilizes electric energy to perform a specific aircraft function.

The specific electric utilization systems which are necessary to maintain controlled flight and effect a safe landing will vary with the type of aircraft and with the nature of the operation in which the aircraft is utilized. Examples of systems which may be in this category are as follows: Basic flight instruments, minimum navigation equipment, minimum two-way radio communications, and control system boost.

Procedures for this purpose should be contained in the Operating Procedures Section of the Airplane Flight Manual (see § 4b.740).

[Supp. 33, 22 F. R. 6885, Aug. 27, 1957]

§ 4b.625-1 Environmental tests for electrical equipment1 (CAA policies which apply to § 4b.625 (a)). The ability of electrical equipment to provide continuous safe service under foreseeable environmental conditions may be demonstrated by means of environmental tests, design analyses, or reference to previous comparable service experience on other aircraft. For environmental testing, the test procedures contained in Appendix (I)2 are acceptable, subject to the following objective criteria:

(a) The extremes of climatic and environmental conditions given in Appendix (I) may be reduced in specific aircraft applications when it can be shown that these extremes would not be reached in normal service. Conversely, these extremes should be extended when individual applications indicate the need, such as may occur when electrical equipment is exposed to high intensity acoustic noise generated by turbo-jet engines.

(b) In all cases the ability of the equipment to safely withstand exposure to temperature extremes, temperature shock, humidity, altitude, vibration, flight and normal landing impact shocks, and acceleration should be demonstrated. Tests for each of these conditions are set forth in Appendix (I).' 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 This policy applies to all electrical generation, distribution, and utilization equipment required by or utilized in complying with the applicable Civil Air Regulations, except those items covered by Technical Standard Orders containing environmental test procedures. 2 Not filed with Federal Register Division.

(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.626-1 Fire resistant electrical equipment (CAA policies which apply to § 4b.626). When applied to the electrical equipment and components defined in the last 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.10 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.

CODIFICATION: § 4b.626-1 was added by Supplement 33, 22 F. R. 6885, Aug. 27, 1957, and subsequently amended to read as set forth above by Supplement 37, 23 F. R. 2790, Apr. 26, 1958.

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.

10 Excessive temperature may affect the electrical equipment and components by causing such malfunctions as short circuit, open circuit, and changes in circuit paramaters (for example, reduced insulation resistance and dielectric strength).

11 In the case of electric cable only a representative length, not less than 12 inches, need to be enveloped in the flame.

CODIFICATION: § 4b.632 was amended as follows by Amendment 4b-4, 22 F. R. 1274, Mar. 1, 1957:

1. In paragraph (a) the reference to paragraph (f) was changed to “(d)”.

2. Paragraph (c) was amended to read as set forth above.

3. Former paragraphs (d) and (e) were revoked and former paragraph (f) was redesignated paragraph (d).

§ 4b.634 Position light distribution and intensities.

CODIFICATION: § 4b.634 was amended as follows by Amendment 4b-4, 22 F. R. 1274, Mar. 1, 1957:

1. Paragraph (c) was deleted.

2. In Figure 4b-18 the last line was deleted from all columns.

3. In Figure 4b-20 the words "or rear red" appearing in the fifth and sixth titles of the first column were deleted.

§ 4b.634-1 Overlaps between high intensity forward position lights (CAA 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]

§ 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

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.

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 steradians 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 source. 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.

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

FIGURE 4b-27-Minimum effective intensities for anticollision lights.

[Amdt. 4b-4, 22 F. R. 1274, Mar. 1, 1957] SAFETY EQUIPMENT

§ 4b.640 Ice protection.

CODIFICATION: In the first sentence of the note following § 4b.640 the words "including engine inlet duct lips and surfaces" were deleted by Amendment 4b-6, 22 F. R. 5566, July 16, 1957.

§ 4b.645 Ditching equipment.

(e) Life line. Provisions shall be made for the storage of life lines, one attached to each side of the fuselage and arranged so that they can be used to enable occupants to stay on the wing after a ditching.

[Paragraph (e) added by Amdt. 4b-6, 22 F. R. 5566, July 16, 1957]

MISCELLANEOUS EQUIPMENT

(a) General. The oxygen system installed shall be free from hazards in itself, in its method of operation, and in its effect upon other components of the airplane. Means shall be provided to enable the crew to determine readily during flight the quantity of oxygen available in each source of supply. For airplanes certificated for operation at flight altitudes above 40,000 feet, oxygen flow rate and equipment shall be approved by the Administrator.

(b) Required minimum mass flow of supplemental oxygen. The minimum mass flow of supplemental oxygen required per person at various cabin pressure altitudes shall be that necessary to comply with the following requirements as applicable:

(1) Where continuous flow equipment is used by flight crew members, the minimum mass flow of supplemental oxygen