in designated fire zones shall be constructed of fireproof materials.

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-6, 17 F. R. 1097, Feb. 5, 1952; Amdt. 4b-8, 18 F. R. 2215, Apr. 18, 1953; Amdt. 4b-2, 20 F.R. 5308, July 26, 1955; Amdt. 4b-6, 22 F.R. 5566, July 16, 1957]

§ 4b.484-1

Determination of carbon dioxide concentration in flight crew compartments (FAA policies which apply to § 4b.484 (b)).

(a) Carbon dioxide has been found to adversely affect flight crew personnel in the performance of their duties. Therefore, in aircraft equipped with built-in carbon dioxide fuselage compartment fire extinguishing systems, the carbon dioxide concentration occurring at the flight crew stations as a result of discharging the fire extinguishers should be determined in accordance with paragraphs (b) and (c) of this section, except that such determination is not considered necessary if:

(1) Five pounds or less of carbon dioxide will be discharged into any one such fuselage compartment in accordance with established fire control procedures,

or

(2) Protective breathing equipment is provided for each flight crew member on flight deck duty.

(b) The carbon dioxide concentrations at breathing level at the flight crew stations should be determined in flight tests during which fuselage compartment fire extinguishers are discharged in accordance with established fire control procedures. Since carbon dioxide is heavier than air, a nose down attitude is likely to produce the critical concentrations in the crew compartment. The following conditions should therefore be investigated:

(1) A rapid descent at the "Never Exceed" speed of the airplane, with flaps and landing gear up,

(2) A rapid descent with flaps and landing gear down, at the maximum permissible speed for this configuration. If it appears that any other condition is likely to be critical on a particular airplane, it should also be investigated.

(c) In the flight tests specified in paragraph (b) of this section, it will be permissible to institute emergency ventilating procedures immediately prior to or following the discharge of carbon dioxide, provided such procedures can be accomplished easily and

quickly by the flight crew and do not appreciably reduce the effectiveness of the fire protection system.

(d) If the carbon dioxide concentrations determined in accordance with paragraphs (b) and (c) of this section exceed 3 percent by volume (corrected to standard sea-level conditions), protective breathing equipment should be provided for each flight crew member on flight deck duty.

(e) Appropriate emergency operating procedures should be entered in the Airplane Flight Manual.

[Supp. 11, 15 F. R. 8904, Dec. 15, 1950]

§ 4b.485 Fire-detector systems.

Quick-acting fire or overheat detectors of an approved type shall be provided in all designated fire zones and in the combustion, turbine, and tailpipe sections of turbine-engine installations, and they shall be sufficient in number and location to assure prompt detection of fire in such zones and sections. Fire detectors shall comply with the following provisions:

(a) Fire detectors shall be constructed and installed to assure their ability to resist without failure all vibration, inertia, and other loads to which they would be subjected in operation.

(b) Fire detectors shall be unaffected by the exposure to oil, water, or other fluids or fumes which might be present.

(c) Means shall be provided to permit the crew to check in flight the functioning of the electric circuit associated with the fire-detection system.

(d) Wiring and other components of detector systems which are located in fire zones shall be of fire-resistant construction.

(e) Detector system components for any fire zone shall not pass through other fire zones, unless they are protected against the possibility of false warnings resulting from fires in zones through which they pass. This requirement shall not be applicable with respect to zones which are simultaneously protected by the same detector and extinguisher systems.

[15 F.R. 3543, June 8, 1950, as amended by Amdt. 4b-6, 17 F.R. 1097, Feb. 5, 1952; Amdt. 4b-6, 22 F.R. 5566, July 16, 1957] § 4b.485-1

Fire detector test circuit (FAA policies which apply to § 4b.485(c)).

(a) The checking means should serve to assure the crew that a fire within the

zone of coverage will produce a fire warning if all fire-responsive (detector) elements are operative. The means need not be designed to disclose whether fire detector sensor elements themselves would respond properly to a fire.*

(b) The check should reveal any probable malfunction or failure in the firedetection system, external to the detector elements, which could interfere with, or prevent, fire warning. Open and short circuits in wiring, and inoperative lights, bells, switches, or relays are examples of malfunctions which should be revealed by such a check.

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

§ 4b.486 Fire walls.

All engines, auxiliary power units, fuel-burning heaters, and other combustion equipment which are intended for operation in flight as well as the combustion, turbine, and tail pipe sections of turbine engines shall be isolated from the remainder of the airplane by means of fire walls, shrouds, or other equivalent means. The following shall apply:

(a) Fire walls and shrouds shall be constructed in such a manner that no hazardous quantity of air, fluids, or flame can pass from the compartment to other portions of the airplane.

(b) All openings in the fire wall or shroud shall be sealed with close-fitting fireproof grommets, bushings, or firewall fittings.

(c) Fire walls and shrouds shall be constructed of fireproof material and shall be protected against corrosion.

[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. 5308, July 26, 1955] § 4b.487 Cowling and nacelle skin.

(a) Cowling shall be constructed and supported so as to make it capable of resisting all vibration, inertia, and air loads to which it would be subjected in operation.

(b) Cowling shall have drainage and ventilation provisions as prescribed in § 4b.489.

(c) On airplanes equipped with a diaphragm complying with § 4b.488, the parts of the accessory section cowling which might be subjected to flame in the event of a fire in the engine power sec

This is normally a separate ground maintenance operation.

tion of the nacelle shall be constructed of fireproof material and shall comply with the provisions of § 4b.486.

(d) Those portions of the cowling which would be subjected to high temperatures due to their proximity to exhaust system parts or exhaust gas impingement shall be constructed of fireproof material.

(e) The airplane shall be so designed and constructed that, in the event of fire originating in the engine power or accessory sections, the probability is extremely remote for fire to enter either through openings or by burning through external skin into any other zone of the nacelle where such fire could create additional hazards. If the airplane is provided with a retractable landing gear, this provision shall apply with the landing gear retracted. Fireproof materials shall be used for all nacelle skin areas which might be subjected to flame in the event of a fire originating in the engine power or accessory sections.

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-6, 17 F. R. 1097, Feb. 5, 1952; Amdt. 4b-8, 18 F. R. 2216, Apr. 18, 1953; Amdt. 4b-2, 20 F. R. 5308, July 26, 1955]

§ 4b.488 Engine accessory section diaphragm.

Unless equivalent protection can be shown by other means, a diaphragm shall be provided on air-cooled engines to isolate the engine power section and all portions of the exhaust system from the engine accessory compartment and on turbine engines to isolate the combustion, turbine, and tail pipe sections from the compressor and accessory sections. This diaphragm shall comply with the provisions of § 4b.486.

[Amdt. 4b-2, 20 F. R. 5308, July 26, 1955]

§ 4b.489 Drainage and ventilation of fire zones.

(a) Complete drainage of all portions of designated fire zones shall be provided to minimize the hazards resulting from failure or malfunctioning of components containing flammable fluids. The drainage provisions shall be effective under conditions expected to prevail when drainage is needed and shall be so arranged that the discharged fluid will not cause an additional fire hazard.

(b) All designated fire zones shall be ventilated to prevent the accumulation of flammable vapors. Ventilation openings shall not be placed in locations which would permit the entrance of

flammable fluids, vapors, or flame from other zones. The ventilation provisions shall be so arranged that the discharged vapors will not cause an additional fire hazard.

(c) Except with respect to the engine power section of the nacelle and the combustion heater ventilating air ducts, provision shall be made to permit the crew to shut off sources of forced ventilation in any fire zone, unless the extinguishing agent capacity and rate of discharge are based on maximum air flow through the zone.

[Amdt. 4b-6, 17 F. R. 1097, Feb. 5, 1952, as amended by Amdt. 4b-2, 20 F. R. 5308, July 26, 1955]

§ 4b.490

Protection of other airplane components against fire.

(a) All airplane surfaces aft of the nacelles, in the region of one nacelle diameter on both sides of the nacelle center line, shall be constructed of fireresistant material. This provision need not be applied to tail surfaces lying behind nacelles, unless the dimensional configuration of the aircraft is such that the tail surfaces could be affected readily by heat, flames, or sparks emanating from a designated fire zone or engine compartment of any nacelle.

(b) Consideration shall be given to the effect on adjacent parts of the airplane of heat within designated fire zones and within the combustion, turbine, and tail pipe sections of turbine engines.

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-6, 17 F. R. 1097, Feb. 5, 1952; Amdt. Amdt. 4b-2, 20 F. R. 5308, July 26, 1955]

The required basic equipment as prescribed in this subpart is the minimum which shall be installed in the airplane for certification. Such additional equipment as is necessary for a specific type of operation is prescribed in the operating rules of this subchapter.

§ 4b.601 Functional and installational requirements.

Each item of equipment shall be: (a) of a type and design appropriate to perform its intended function,

(b) Labeled as to its identification, function, or operational limitations, or any combination of these, whichever is applicable,

(See § 4b.612 for installation requirements.)

(a) Air-speed indicating system. If the air-speed limitations vary with altitude, the air-speed indicator shall incorporate a maximum allowable airspeed indication showing the variation of VNE with altitude including compressibility limitations. (See § 4b.732.)

(b) Altimeter (sensitive or precision type),

(c) Rate-of-climb indicator (vertical speed),

(d) Free air temperature indicator, (e) Clock (sweep-second pointer type),

(f) Rate-of-turn indicator (gyroscopic type with integral bank or slip indicator),

(g) Bank and pitch indicator (gyroscopically stabilized),

(h) Direction indicator (gyroscopically stabilized magnetic and/or nonmagnetic type),

(i) Direction indicator (nonstabilized type magnetic compass),

(j) Machmeter for airplanes having compressibility limitations not otherwise indicated to the pilot in accordance with § 4b.732.

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

§ 4b.604 Powerplant instruments.

(See § 4b.613 for installation requirements.)

(a) Carburetor air temperature indicator for each reciprocating engine.

(b) Cylinder head temperature indicator for each air-cooled reciprocating engine.

(c) Gas temperature indicator for each turbine engine.

(d) Manifold pressure indicator for each reciprocating engine.

(e) Fuel pressure indicator for each reciprocating engine to indicate the

pressure under which the fuel is being supplied.

(f) Fuel pressure warning means for each engine or a master warning means for all engines with provision for isolating the individual warning means from the master warning means.

(g) Fuel flowmeter indicator for each turbine engine. For reciprocating engines, a fuel flowmeter or fuel mixture indicator for each engine not equipped with an automatic altitude mixture control

(h) Fuel quantity indicator for each fuel tank.

(i) Augmentation liquid quantity indicator for each tank which is appropriate to the manner in which the liquid is to be used in operations.

(j) Oil quantity indicator for each oil tank. (See § 4b.613 (d).)

(k) Oil pressure indicator for each independent pressure oil system of each engine.

(1) Oil pressure warning means for each engine or a master warning means for all engines with provision for isolating the individual warning means from the master warning means.

(m) Oil temperature indication for each engine.

(n) Tachometer for each reciprocating engine.

(0) Tachometer for each turbine engine to indicate the speed of the rotors for which limiting speeds have been established.

(p) Fire-warning indicators. § 4b.485.)

(See

(q) Thrust indicator for each turbojet engine.

(r) A torque indicator for each turbine-propeller engine. A device for each reciprocating engine capable of indicating to the flight crew during flight any change in the power output if the engine is equipped with an automatic propeller feathering system, the operation of which is initiated by a power output measuring system, or if the total engine cylinder displacement is 2,000 cubic inches or more.

(s) Position indicating means for each propeller on a turbine engine to indicate to the flight crew when the propeller blade angle is below the flight low pitch position (see § 4b.613). For reciprocating engines, a means for each re

versing propeller to indicate to the pilot when the propeller is in reverse pitch.

(t) Position indicating means for each turbine engine utilizing a thrust reversing device to indicate to the flight crew when the device is in the reverse thrust position.

[Amdt. 4b-6, 22 F. R. 5566, July 16, 1957] § 4b.605 Miscellaneous equipment.

(a) Approved seats for all occupants (see § 4b.358).

(b) Approved safety belts for all occupants (see § 4b.643),

(c) [Reserved]

(d) Source(s) of electrical energy (see § 4b.620),

(e) Electrical protective devices (see § 4b.624),

(f) Radio communication system (two-way),

(g) Radio navigation system,

(h) Windshield wiper or equivalent for each pilot,

(i) Ignition switch for each and all engines (see § 4b.472),

(j) Approved portable fire extinguisher (see § 4b.641).

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-7, 17 F.R. 11631, Dec. 20, 1952; Amdt. 4b-6, 22 F.R. 5566, July 16, 1957]

§ 4b.606 Equipment, systems, and in

stallations.

(a) Functioning and reliability. All equipment, systems, and installations the functioning of which is necessary in showing compliance with the regulations in this subchapter shall be designed and installed to insure that they will perform their intended functions reliably under all reasonably foreseeable operating conditions.

(b) Hazards. All equipment, systems, and installations shall be designed to safeguard against hazards to the airplane in the event of their malfunctioning or failure.

(c) Power supply. Where an installation the functioning of which is necessary in showing compliance with the regulations of this subchapter requires a power supply, such installation shall be considered an essential load on the power supply, and the power sources and the system shall be capable of supplying the following power loads in probable operating combinations and for probable durations:

(1) All loads connected to the system with the system functioning normally;

(2) All essential loads after failure of any one prime mover, power converter, = or energy storage device;

(3) All essential loads after failure of any one engine on two- or three-engine airplanes, or after failure of any two | engines on four-or-more-engine airplanes;

(4) In determining the probable operating combinations and durations of essential loads for the partial power failure conditions prescribed in subparagraphs (2) and (3) of this paragraph, it shall be permissible to assume that the power loads are reduced in accordance with a monitoring procedure which is consistent with safety in the types of operations authorized. If a particular load is not required to maintain controlled flight it need not be considered for the two-engine-inoperative condition on airplanes with four or more engines as prescribed in subparagraph (3) of this paragraph.

[Amdt. 4b-6, 17 F. R. 1097, Feb. 5, 1952, as amended by Amdt. 4b-1, 19 F. R. 2250, Apr. 20, 1954]

§ 4b.606-1 Safety criteria1 for electric utilization system; (FAA policies which apply to § 4b.606 (a) and (b)).

1 When applying these criteria to particular systems, it should be clear that the degree of hazard resulting from a type of malfunction may vary considerably with the type of aircraft in which the system is installed, or with the nature of the operation in which the aircraft is utilized. Examples of systems which should be considered under certain of the above criteria are as follows: (a) Basic flight instruments, minimum navigation equipment; (b) propeller reversing system, trimtab system, dive brake system, landing gear actuation systems; (c) fuel control valve system, propeller control system; (d) landing gear indicating system, radio navigation system, instrument landing system, gyroscopic instrument systems. Additional safety criteria are contained in sections of this part applicable to particular systems and components of the airplane.

2 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 system includes all electric components beyond the nearest bus or sub-bus from which electric energy is supplied. Examples of such systems are: propeller control system, elec

conformance to the following safety criteria.

(a) Loss of system function. The system should not be rendered inoperative by any probable malfunction," if operation of this system is necessary to maintain controlled flight or effect a safe landing for any authorized flight operation.

(b) Inadvertent operation of system. The system should not be inadvertently set into operation by any probable malfunction, if such inadvertent operation can result in the inability to maintain controlled flight or effect a safe landing for any authorized flight operation.

(c) Systems serving two or more engines. No probable malfunction in the system should adversely affect the performance of more than one propulsion engine, consistent with the provisions of § 4b.401 (b).

(d) System independence. No probable malfunction in one system should render another system inoperative, if both systems are necessary in showing. compliance with this part.

(e) Misleading system indicators. No probable malfunction in the system should result in a safe indication of an unsafe condition of flight, if such misleading information can result in the inability to maintain controlled fight or effect a safe landing for any authorized flight operation.

(f) System overheat. No probable malfunction in the system should result in overheat of electric equipment, such that hazardous quantities of smoke are generated within the cabin, or such that a fire hazard is created, unless adequate

tric flight instrument system, radio navigation equipment system, fuel valve control system, flap and landing gear actuating systems.

A probable malfunction is any single electrical or mechanical malfunction or failure within a utilization system which is considered probable on the basis of past service experience with similar components in aircraft applications. This definition should be extended to multiple malfunctions when: (1) The first malfunction 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.

This definition of "probable malfunction" applies wherever this term is used in this section.