ACCESSORIES

§ 3.635 Powerplant accessories.

Engine-driven accessories shall be of a type satisfactory for installation on the engine involved and shall utilize the provisions made on the engine for the mounting of such units. Items of electrical equipment subject to arcing or sparking shall be installed so as to minimize the possibility of their contact with any inflammable fluids or vapors which might be present in a free state.

§ 3.636 Engine battery ignition systems.

(a) Battery ignition systems shall be supplemented with a generator which is automatically made available as an alternate source of electrical energy to permit continued engine operation in the event of the depletion of any battery.

(b) The capacity of batteries and generators shall be sufficient to meet the simultaneous demands of the engine ignition system and the greatest demands of any of the airplane's electrical system components which may draw electrical energy from the same source. Consideration shall be given to the condition of an inoperative generator, and to the condition of a completely depleted battery when the generator is running at its normal operating speed. If only one battery is provided, consideration shall also be given to the condition in which the battery is completely depleted and the generator is operating at idling speed.

(c) Means shall be provided to warn the appropriate flight personnel if malfunctioning of any part of the electrical system is causing the continuous discharging of a battery used for engine ignition. (See § 3.629 for ignition switches.)

POWERPLANT FIRE PROTECTION

§ 3.637 Flammable fluids; shutoff

means.

The provisions of paragraphs (a) through (d) of this section shall be applicable to multiengine aircraft which are required to comply with the provisions of § 3.85 (b).

(a) Means for each individual engine shall be provided for shutting off or otherwise preventing hazardous quantities of fuel, oil, de-icer, and other flammable fluids from flowing into, within, or through the engine compartment except that means need not be provided to shut off flow in lines forming an integral

part of an engine. Closing the fuel shutoff valve for any engine shall not make any of the fuel supply unavailable to the remaining engines.

(b) Operation of the shutoff means shall not interfere with the subsequent emergency operation of other equipment, such as feathering the propeller.

(c) The shutoff means shall be located outside of the engine compartment unless an equally high degree of safety is otherwise provided. It shall be shown that no hazardous quantity of flammable fluid could drain into the engine compartment after shutting off has been accomplished.

(d) Provisions shall be made to guard against inadvertent operation of the shutoff means and to make it possible for the crew to reopen the shutoff means in flight after it has once been closed. [Amdt. 3-2, 22 F. R. 5562, July 16, 1957]

§ 3.638 Lines and fittings.

All lines and fittings carrying flammable fluids or gases in the engine compartment shall comply with the provisions of paragraphs (a) through (c) of this section.

(a) All lines and fittings carrying flammable fluids in the engine compartment shall be fire resistant, except as otherwise provided in this section. If flexible hose is used, the assembly of hose and end fittings shall be of an approved type. The provisions of this paragraph | need not apply to those lines and fittings which form an integral part of the engine.

(b) Vent and drain lines and their fittings shall be subject to the provisions of paragraph (a) of this section unless a failure of such line or fitting will not result in, or add to, a fire hazard.

(c) Vent and drain lines and their fittings shall be subject to the provisions of paragraphs (a) and (b) of this section, unless a failure of such line or fitting will not result in, or add to, a fire hazard. [Amdt. 3-2, 22 F.R. 5562, July 17, 1957, as amended by Amdt. 3-5, 24 F.R. 7067, Sept. 1, 1959]

Subpart F-Equipment

§ 3.651 General.

The equipment specified in § 3.655 shall be the minimum installed when the airplane is submitted to determine its compliance with the airworthiness requirements. Such additional equipment as is necessary for a specific type of op

eration is specified in other pertinent parts of this subchapter, but, where necessary, its installation and that of the items mentioned in § 3.655 is covered by this part.

§ 3.652 Functional and installational requirements.

Each item of equipment which is essential to the safe operation of the airplane shall be found by the Administrator to perform adequately the functions for which it is to be used, shall function properly when installed, and shall be adequately labeled as to its identification, function, operational limitations, or any combination of these, whichever is applicable.

(a) The phrase "Each item of equipment which is essential to the same operation of the airplane * *" includes radio communication and navigation equipment installed on the airplane.

(b) The phrase "shall function properly when installed" is interpreted to mean that the installation shall comply with the requirements specified in § 3.721. [Supp. 25, 22 F. R. 135, Jan. 5, 1957] § 3.652-2 Radio installation performance (FAA policies which apply to § 3.652).

The prototype installation should be flight tested by the airplane manufacturer to determine that it performs the intended function.

[Supp. 25, 22 F. R. 135, Jan. 5, 1957]

(iii) Oil temperature indicator. (iv) Tachometer.

(2) For each engine or tank (if required in reference section). (i) Cylinder head temperature indicator (see § 3.675).

(ii) Fuel pressure indicator (if pumpfed engines used).

(iii) Manifold pressure indicator (if altitude engines used).

(iv) Oil quantity indicator (see § 3.674).

(c) Electrical equipment (if required by reference section). (1) Master switch arrangement (see § 3.688).

(2) Adequate source(s) of electrical energy (see §§ 3.682 and 3.685).

(3) Electrical protective devices (see § 3.690).

(d) (1) Miscellaneous equipment. Approved safety belts for all occupants (see 3.715).

(2) Airplane Flight Manual if required by § 3.777.

[21 F.R. 3339, May 22, 1956, as amended by Amdt. 305, 24 F.R. 7067, Sept. 1, 1959]

INSTRUMENTS; INSTALLATION

Vibration characteristics of the instrument panel shall not be such as to impair the accuracy of the instruments or to cause damage to them.

FLIGHT AND NAVIGATIONAL INSTRUMENTS § 3.663 Air-speed indicating system.

This system shall be so installed that the air-speed indicator shall indicate true air speed at sea level under standard conditions to within an allowable installational error of not more than plus or minus 3 percent of the calibrated air speed or 5 miles per hour, whichever is greater, throughout the operating range of the airplane with flaps up from Ve to

1.3 Vs, and with flaps down at 1.3 Vs1. The calibration shall be made in flight. § 3.664 Air-speed indicator marking.

The air-speed indicator shall be marked as specified in § 3.757.

§ 3.665 Static air vent system.

All instruments provided with static air case connections shall be so vented that the influence of airplane speed, the opening and closing of windows, air-flow variation, moisture, or other foreign matter will not seriously affect their accuracy.

§ 3.666 Magnetic direction indicator.

The magnetic direction indicator shall be so installed that its accuracy shall not be excessively affected by the airplane's vibration or magnetic fields. After the direction indicator has been compensated, the installation shall be such that the deviation in level flight does not exceed 10 degrees on any heading. A suitable calibration placard shall be provided as specified in § 3.758. § 3.667 Automatic pilot system.

If an automatic pilot system is installed, compliance shall be shown with the provisions of paragraphs (a) through (e) of this section.

(a) The system shall be so designed that the automatic pilot can either be quickly and positively disengaged by the human pilot to prevent it from interfering with the control of the airplane, or be overpowered by the human pilot to enable him to control the airplane.

(b) A means shall be provided to indicate readily to the pilot the alignment of the actuating device in relation to the control system which it operates, except when automatic synchronization is provided.

(c) The manually operated control(s) for the system's operation shall be readily accessible to the pilot. Controls shall operate in the same plane and sense of motion as specified for the cockpit controls in § 3.384 and Figure 3-14. The direction of motion shall be plainly indicated on or adjacent to each control.

(d) The automatic pilot system shall be of such design and so adjusted that, within the range of adjustment available to the human pilot, it cannot produce hazardous loads on the airplane or create hazardous deviations in the flight path under any conditions of flight ap

propriate to its use either during normal operation or in the event of malfunctioning, assuming that corrective action is initiated within a reasonable period of time.

(e) The system design shall be such that a single malfunction will not produce a hardover signal in more than one control axis. When the automatic pilot integrates signals from auxiliary controls or furnishes signals for operation of other equipment, positive interlocks and sequencing of engagement shall be provided to preclude improper operation. Protection against adverse interaction of integrated components resulting from a malfunction shall be provided. [Amdt. 3-2, 22 F. R. 5562, July 16, 1957] § 3.668 Gyroscopic indicators.

All gyroscopic instruments installed in airplanes shall derive their energy from a power source of sufficient capacity to maintain their required accuracy at all airplane speeds above the best rate-of-climb speed. They shall be installed to preclude malfunctioning due to rain, oil, and other detrimental elements. Means shall be provided for indicating the adequacy of the power being supplied to the instruments. In addition, the following provisions shall be applicable to multiengine airplanes:

(a) There shall be provided at least two independent sources of power, a manual or an automatic means for selecting the power source, and a means for indicating the adequacy of the power being supplied by each source.

NOTE: Power sources are not considered Independent if both sources are driven by the same engine.

(b) The installation and power supply systems shall be such that failure of one instrument or of the energy supply from one source will not interfere with the proper supply of energy to the remaining instruments or from the other

source.

[21 F.R. 3339, May 22, 1956, as amended by Amdt. 3-3, 23 F.R. 2590, Apr. 19, 1958; Amdt. 3-5, 24 F.R. 7067, Sept. 1, 1959]

§ 3.669 Flight director instrument.

If a flight director instrument is installed, its installation shall not affect the performance and accuracy of the required instruments. A means for disconnecting the flight director instrument from the required instruments or their installations shall be provided.

POWERPLANT INSTRUMENTS

§ 3.670 Operational markings. Instruments shall be marked as specified in § 3.759.

§ 3.671 Instrument lines.

Powerplant instrument lines shall comply with the provisions of § 3.550. In addition, instrument lines carrying inflammable fluids or gases under pressure shall be provided with restricted orifices or other safety devices at the source of the pressure to prevent escape of excessive fluid or gas in case of line failure.

§ 3.672 Fuel quantity indicator.

Means shall be provided to indicate to the flight personnel the quantity of fuel in each tank during flight. Tanks, the outlets and air spaces of which are interconnected, may be considered as one tank and need not be provided with separate indicators. Exposed sight gauges shall be so installed and guarded as to preclude the possibility of breakage or damage. Sight gauges which form a trap in which water can collect and freeze shall be provided with means to permit drainage on the ground. Fuel quantity gauges shall be calibrated to read zero during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply as defined by § 3.437. Fuel gauges need not be provided for small auxiliary tanks which are used only to transfer fuel to other tanks, provided that the relative size of the tanks, the rate of fuel transfer, and the instructions pertaining to the use of the tanks are adequate to guard against overflow and to assume that the crew will receive prompt warning in case transfer is not being achieved as intended.

§ 3.672-1 Means to indicate fuel quantity (FAA policies which apply to § 3.672).

The Administrator will accept, as a "means to indicate to the flight personnel the quantity of fuel in each tank during flight,” a fuel tank calibrated to read in either gallons or pounds, providing the gauge is clearly marked to indicate which scale is being used.

[Supp. 1, 12 F. R. 3438, May 28, 1947, as amended by Amdt. 1, 14 F. R. 36, Jan. 5, 1949] § 3.673 Fuel flowmeter system.

When a fuel flowmeter system is installed in the fuel line(s), the metering

component shall be of such design as to include a suitable means for bypassing the fuel supply in the event that malfunctioning of the metering component offers a severe restriction to fuel flow. § 3.674 Oil quantity indicator.

Ground means, such as a stick gauge, shall be provided to indicate the quantity of oil in each tank. If an oil transfer system or a reserve oil supply system is installed, means shall be provided to indicate to the flight personnel during flight the quantity of oil in each tank. § 3.675 Cylinder head temperature indicating system for air-cooled engines.

A cylinder head temperature indicator shall be provided for each engine on airplanes equipped with cowl flaps. In the case of airplanes which do not have cowl flaps, an indicator shall be provided if compliance with the provisions of § 3.581 is demonstrated at a speed in excess of the speed of best rate of climb.

ELECTRICAL SYSTEMS AND EQUIPMENT § 3.681

Installation.

(a) Electrical systems in airplanes shall be free from hazards in themselves, in their method of operation, and in their effects on other parts of the airplane. Electrical equipment shall be of a type and design adequate for the use intended. Electrical systems shall be installed in such a manner that they are suitably protected from fuel, oil, water, other detrimental substances, and mechanical damage.

(b) Items of electrical equipment required for a specific type of operation are listed in other pertinent parts of this subchapter.

§ 3.681-1 Shielding of flare circuits (FAA policies which apply to § 3.681).

Flare circuits should be shielded or separated from other circuits far enough to preclude induction of other current into flare circuit.

[Supp. 10, 16 F. R. 3292, Apr. 14, 1951] § 3.681-2 Generator capacity (FAA policies which apply to § 3.681). When a generator is required,' its capacity should be sufficient to supply

A generator of adequate capacity is required by § 43.30 (c) (7) of this subchapter for operation under instrument flight rules.

during flight all probable combinations of continuous loads,2 with adequate reserve for storage battery charging. In no case should the maximum probable continuous load exceed 80 percent of total generator rating.

[Supp. 26, 22 F. R. 1025, Feb. 20, 1957]

BATTERIES

§ 3.682 Batteries.

When an item of electrical equipment which is essential to the safe operation of the airplane is installed, the battery required shall have sufficient capacity to supply the electrical power necessary for dependable operation of the connected electrical equipment.

§ 3.682–1 Dry-cell batteries (FAA policies which apply to § 3.682).

When a battery is installed to provide power for electrical equipment which is essential to the safe operation of the airplane, it should be of a type whose pre-flight state of charge can readily be determined by simple and reliable means. Dry-cell batteries are not considered to be of this type, and should not be used to supply essential electrical equipment.

[Supp. 11, 16 F. R. 3211, Apr. 12, 1951]

§ 3.683 Storage battery design and installation.

Storage batteries shall be of such design and be so installed that:

(a) Safe cell temperatures and pressures are maintained during any probable charging or discharging condition. No uncontrolled increase in cell temperature shall result when the storage battery is recharged (after previous complete discharge) at maximum regulated voltage, during a flight of maximum duration, under the most adverse cooling condition likely to occur in service. Tests to demonstrate compliance with this regulation shall not be required if satisfactory operating experience with similar batteries and installations has shown that maintaining safe cell temperatures and pressures presents no problem.

2 Continuous loads are those which draw current continuously during flight, such as radio equipment and position lights. Occasional intermittent loads (such as landing gear, flaps, or landing lights) are not considered.

Generators shall be capable of delivering their continuous rated power. § 3.686 Generator controls.

(a) Generator voltage control equipment shall be capable of dependably regulating the generator output within rated limits.

(b) A generator reverse current cutout shall be incorporated and designed to disconnect the generator from the battery and other generators when the generator is developing a voltage of such value that current sufficient to cause malfunctioning can flow into the generator.

[21 F.R. 3999, May 22, 1956, as amended by Amdt. 3-3, 23 F.R. 2590, Apr. 19, 1958]

INSTRUMENTS

§ 3.687 Electric power system instru

ments.

Means shall be provided to indicate to appropriate crew members those electric power system quantities which are essential for the safe operation of the system.

NOTE: For direct current systems an ammeter which can be switched into each generator feeder would be acceptable. When only one generator is installed, the ammeter may be in the battery feeder. [Amdt. 3-3, 23 F. R. 2590, Apr. 19, 1958) MASTER SWITCH

§ 3.688 Arrangement.

If electrical equipment is installed, master switch arrangement shall be provided which will disconnect all sources of electrical power from the main distribution system at a point adjacent to the power sources.