of the airplane in the event of a loss of one life raft of the largest rated capacity on board. Each life raft shall be equipped with a trailing line and with a static line, the latter designed to hold the raft near the airplane but to release it in case the airplane becomes totally submerged. Each raft shall contain obvious markings of instruction on the operation of the raft.

(b) Life raft equipment. Approved equipment intended for survival shall be attached to each life raft and marked for identification and method of operation.

NOTE: The extent and cype of survival equipment will depend upon the route over which the airplane is operated.

(c) Long-range signalling device. An approved long-range signalling device shall be provided for use in one of the life rafts.

(d) Life preservers. Life preservers shall be of an approved type. They shall be reversible and shall contain obvious markings of instruction on their use.

(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.

[Amdt. 4b-8, 18 FR. 2216, Apr. 18, 1953, as amended by Amdt. 4b-6, 22 F.R. 5566, July 16, 1957; Amdt. 4b-11, 24 F.R. 7071, Sept. 1, 1959]

§ 4b.646 Stowage of safety equipment.

Special stowage provisions shall be made for all prescribed safety equipment to be used in emergencies. The stowage provision shall be such that the equipment is directly accessible and its location is obvious. All safety equipment shall be protected against inadvertent damage. The stowage provisions shall be marked conspicuously to identify the contents and to facilitate removal of the equipment. In addition, the following shall specifically apply.

(a) Emergency exit means. The stowage provisions for the emergency exit means required by § 4b.362 (e) (7) shall be located at the exits which they are intended to serve.

(b) Life rafts. The provisions for the stowage of life rafts required by § 4b.645 (a) shall accommodate a sufficient number of rafts for the maximum number of occupants for which the airplane is cer

tificated for ditching. Stowage shall be near exits through which the rafts can be launched during an unplanned ditching. Rafts automatically or remotely released on the outside of the airplane shall be attached to the airplane by means of the static line prescribed in § 4b.645 (a).

(c) Long-range signalling device. The stowage provisions for the long-range signalling device required by § 4b.645 (c) shall be located near an exit to be available during an unplanned ditching.

(d) Life preservers. The provisions for the stowage of life preservers required by § 4b.645 (d) shall accommodate one life preserver for each occupant for which the airplane is certificated for ditching. They shall be located so that a life preserver is within easy reach of each occupant while seated. [Amdt. 4b-8, 18 F. R. 2217, Apr. 18, 1953] § 4b.647 Flotation means.

If the airplane is not equipped with life preservers in accordance with § 4b.645 (d), an approved individual flotation means shall be provided for each occupant. Such flotation means shall be within easy reach of each occupant while seated and readily removable from the airplane.

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

(a) In showing compliance with § 4b.606 (a) and (b) with respect to radio and electronic equipment and their installations, consideration shall be given to critical environmental conditions.

NOTE: Critical environmental conditions may include temperature, pressure, humidity, ventilation, position, acceleration, vibration, and presence of detrimental substances.

(b) Radio and electronic equipment shall be supplied with power in accordance with the provisions of § 4b.623 (c).

(c) All radio and electronic equipment, controls, and wiring shall be so installed that operation of any one unit or system of units will not affect adversely the simultaneous operation of any other radio or electronic unit or system of units required by the regulations in this subchapter.

[Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952]

§ 4b.651 Oxygen equipment and supply.

When required by the operating rules of the regulations in this subpart, the supplemental and protective breathing equipment and its installation shall meet the following requirements.

(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 required for each crew member shall not be less than that which will maintain during inspiration a mean tracheal oxygen partial pressure of 149 mm. Hg. when breathing 15 liters per minute, BTPS, and having a maximum tidal volume of 700 cc. with a constant time interval between respirations.

(2) Where demand equipment is used by flight crew members, the minimum mass flow of supplemental oxygen required for each crew member shall not be less than that which will maintain during inspiration a mean tracheal oxygen partial pressure of 122 mm. Hg. to and including a cabin pressure altitude of 35,000 feet and 95 percent oxygen between cabin pressure altitudes of 35,000 and 40,000 feet, when breathing 20 liters per minute BTPS. Provision shall be made to allow use of undiluted oxygen by crew members when they so desire.

(3) For passengers and cabin attendants the minimum mass flow of supplemental oxygen required for each person at various cabin pressure altitudes shall not be less than that which will maintain during inspiration the following mean tracheal oxygen partial pressures when using the oxygen equipment provided, including masks:

(i) At cabin pressure altitudes above 10,000 feet to and including 18,500 feet, a mean tracheal oxygen partial pressure of 100 mm. Hg. when breathing 15 liters per minute, BTPS, and having a tidal volume of 700 cc. with a constant time interval between respirations.

(ii) At cabin pressure altitudes above 18,500 feet to and including 40,000 feet, a mean tracheal oxygen partial pressure of 83.8 mm. Hg. when breathing 30 liters per minute, BTPS, and having a tidal volume of 1,100 cc. with a constant time interval between respirations.

(4) Where first-aid oxygen equipment is required, the minimum mass flow of oxygen to each user shall not be less than 4 liters per minute, STPD, except that means may be provided to decrease this flow to not less than 2 liters per minute, STPD, at any cabin altitude. The quantity of oxygen required shall be based upon an average flow rate of 3 liters per minute per person for whom first-aid oxygen is required.

(5) Where portable oxygen equipment is required for crew members, the minimum mass flow of supplemental oxygen shall be as specified in subparagraph (1) or (2) of this paragraph, whichever is applicable.

(c) Equipment standards for distribution system. Where oxygen is to be supplied to both crew and passengers, the distribution system shall be designed to provide either:

(1) A source of supply for the flight crew on duty and a separate source for the passengers and other crew members, or

(2) A common source of supply with means provided so that the minimum supply required by the flight crew on duty can be separately reserved.

(d) Equipment standards for dispensing units. Where oxygen dispensing units are required, they shall comply with the provisions of subparagraphs (1) through (3) of this paragraph.

(1) An individual dispensing unit shall be provided for each occupant for whom supplemental oxygen is required to be furnished. All units shall be designed to cover the nose and mouth and shall be equipped with a suitable means for retaining the unit in position on the face for use. Flight crew masks for supplemental oxygen shall provide for the use of communication equipment. (For crew masks to be used for protec

tive breathing purposes, see paragraph (h) of this section.)

(2) In airplanes certificated to operate at flight altitudes to and including 25,000 feet, there shall be available to and within reach of each flight crew member an oxygen supply terminal and unit of oxygen dispensing equipment to provide for the immediate use of oxygen by such crew member. For all other occupants the supply terminals and dispensing equipment shall be located so as to permit the use of oxygen as required by the operating rules of the regulations in this subchapter.

(3) In airplanes certificated to operate above 25,000 feet flight altitude, the provisions of subdivisions (i) through (iv) of this subparagraph shall apply:

(i) An oxygen dispensing unit connected to oxygen supply terminals shall be immediately available to each occupant wherever seated. In addition, in airplanes certificated to operate above 30,000 feet, the dispensing units providing the required oxygen flow rate shall be automatically presented to the occupants. To insure that sufficient dispensing units and outlets are available for all occupants, the total number shall exceed the number of seats by at least 10 percent with the extra units being as uniformly distributed throughout the cabin as practicable;

(ii) Crew members on flight deck duty shall be provided with demand equipment. An oxygen dispensing unit connected to an oxygen supply terminal shall be immediately available to each flight crew member when seated at his station;

(iii) Not less than two outlets and units of dispensing equipment of a type similar to that required by subdivision (i) of this subparagraph shall be located in each washroom; and in each lavatory if separate from the washroom; and

(iv) Portable oxygen equipment shall be immediately available for each cabin attendant.

(e) Means for determining use of oxygen. Means shall be provided to enable the crew to determine whether oxygen is being delivered to the dispensing units.

(f) Fire protection. (1) Oxygen equipment and lines shall not be located in any designated fire zone.

(2) Oxygen equipment and lines shall be protected from heat which may be

generated in or escape from any designated fire zone.

(3) Oxygen equipment and lines shall be so installed that escaping oxygen cannot cause ignition of accumulations of grease, fluids, or vapors which are likely to be present in normal operation or as a result of failure or malfunctioning of any system.

(g) Protection from rupture. Oxygen pressure tanks and lines between tanks and the shutoff means shall be protected from the effects of unsafe temperatures, and shall be so located in the airplane as to minimize the possibility and the hazards of rupture in a crash landing.

(h) Protective breathing system. When protective breathing equipment is required by the Civil Air Regulations, it shall be designed to protect the flight crew from the effects of smoke, carbon dioxide, and other harmful gases while on flight deck duty and while combating fires in cargo compartments (see § 4b.380 (c)). The protective breathing equipment and the necessary supply of oxygen shall be in accordance with the following provisions.

(1) The protective breathing equipment shall include masks covering the eyes, nose, and mouth, or only the nose and mouth when accessory equipment is provided to protect the eyes. Such equip. ment while in use shall not prevent the flight crew from using the radio equipment of the airplane or from communicating with each other while at their assigned duty stations. That part of the equipment provided to protect the eyes shall be of a type and construction which will not cause any appreciable adverse effect on vision and shall permit wearing corrective glasses by individual members of the flight crew.

(2) A supply of protective oxygen per crew member shall be of 15-minute duration at a pressure altitude of 8,000 feet and a respiratory minute volume of 30 liters per minute BTPD.

NOTE: When a demand type oxygen system is employed, a supply of 300 liters of free oxygen at 70° F. and 760 mm Hg. pressure is considered to be of 15-minute duration at the prescribed altitude and minute volume. When a continuous flow protective breathing system is used, including a mask with a standard rebreather bag, a flow rate of 60 liters per minute at 8,000 feet (45 liters per minute at sea level) and a supply of 600 liters of free oxygen at 70° F. and 760 mm Hg. pressure is considered to be of 15-minute

duration at prescribed altitude and minute volume. (BTPD refers to body temperature conditions, i. e., 37° C., at ambient pressure, dry.)

[15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-1, 15 F. R. 8903, Dec. 15, 1950; Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952; Amdt. 4b-8, 18 F. R. 2217, Apr. 18, 1953; Amdt. 4b-8, 23 F. R. 2591, Apr. 19, 1958; Amdt. 4b-9, 23 F. R. 6743, Aug. 30, 1958] § 4b.651-1 Safety precautions (FAA policies which apply to § 4b.651(a)).

The oxygen system should be so located that leakage or failure in other systems carrying inflammable liquids or gases will not cause the inflammable liquid or gas to come in contact with oxygen lines or equipment. A relief valve or some other means is desirable in low pressure (400 psi) oxygen systems to safely relieve excessive pressures such as might be caused by overcharging. (See also § 4b.481 concerning location of tanks containing flammable fluids.) [Supp. 11, 15 F.R. 8904, Dec. 15, 1950] § 4b.651-2 Protective breathing equipment (FAA policies which apply to § 4b.651 (h)).

(a) Conditions under which protective breathing equipment may be necessary. These conditions are those outlined in § 4b.484.1, and §§ 40.205-2, 41.24c-2 and 42.29-2 this chapter.

(b) Oxygen systems for flight deck duty. The demand type oxygen system, or the diluter-demand type system with the lever of the diluter-demand regulator set at "100% OXYGEN" (Automix "OFF") are recommended for use as protective breathing equipment. However, a continuous flow protective breathing system may also be used. In any case the equipment should meet the requirements of § 4b.651 (h).

(c) Portable equipment for flight deck duty. Portable protective breathing units of the demand type may be used to meet the requirement of § 4b.651 in lieu of installing a fixed protective breathing system. Portable continuous flow protective breathing units may also be used, but should not be used during fire fighting in Class A or B cargo compartments since any unused oxygen escaping from around the face mask might aggravate the existing fire.

(d) Masks and goggles. (1) Protective breathing masks should fit snugly to prevent the entry of noxious gases.

Continuous flow protective breathing masks should have no apertures through which outside air could be drawn into the system and should have a rebreathing bag of at least 3 liters capacity. The masks should be installed so as to be readily available to the appropriate crew members. It should be possible for at least the pilot or copilot to maintain ground to air radio voice communications when utilizing the protective breathing masks.

(2) Eye protecting goggles may be a part of or separate from the breathing mask. The goggles should provide an adequate field of vision and a means should be provided to overcome any unsatisfactory fogging tendency of the goggles. Periodic application of an effective anti-fogging agent on the lens is a satisfactory means of overcoming fogging.

(e) Operating instructions. Operating instructions appropriate to the type of system and masks installed should be provided for the flight crew on placards and/or in the Airplane Flight Manual. [Supp. 24, 19 F. R. 4466, July 20, 1954]

§ 4b.651-3 Supplemental breathing equipment (FAA policies which apply to § 4b.651).

(a) Oxygen systems. (1) Either a continuous flow type system which uses a rebreather type mask or a diluterdemand type system with the lever of the diluter-demand regulator set in the "NORMAL" (Automix "ON") position will satisfactorily provide the supplemental oxygen required for protection against anoxia. The continuous flow system may be of the type which controls the oxygen flow by means of a hand adjustment type regulator, or an automatic type regulator.

(2) A diluter-demand type system with the lever of the diluter-demand regulator set in the "100% OXYGEN” (Automix "OFF") position or a straight demand type system which uses a nondiluter-demand regulator may be used for supplementary breathing purposes as protection against anoxia. However, such use is not recommended due to the lack of oxygen economy of these systems when used to supply supplementary oxygen. As mentioned in § 4b.651-2, either of these closed demand systems is satisfactory for protection against toxic gases.

(b) Operating instructions. Operating instructions appropriate to the type of system and masks installed should be provided for the flight crew and other crew members concerned. These instructions should include a graph or a table which will show the duration of the oxygen supply for the various bottle pressures and pressure altitudes. [Supp. 21, 17 F. R. 11712, Dec. 24, 1952] § 4b.651-4 Design considerations for fixed systems (FAA policies which apply to § 4b.651).

(a) Location of outlets and equipment for crew members. Protective breathing equipment should be immediately available for use. It is also desirable that supplementary breathing equipment be available for immediate use; however, the supplemental masks may be stowed in any location in the airplane provided operation procedures require that supplemental masks are at each crew member location when needed. The oxygen outlet should be within reach; the oxygen mask should be stored in such a way that there will be a minimum delay in removing it and putting it into use. Provisions for keeping the masks sanitary and clean are desirable, but cumbersome wrapping or packaging of the mask which involve unnecessary effort and time to open should be avoided. The location of the oxygen outlet for a crew member and the length of tubing connecting the mask of the crew member and his oxygen outlet should be such that the visibility and the movement required of the crew member in the performance of his duties are not impaired or restricted in any way. It should not be necessary for the crew member to loosen or unfasten his seat belt in order for him to obtain his oxygen equipment and to put the system into use.

(b) Location of outlets for passengers. The operating regulations require that oxygen be furnished for certain percentages of the passengers at cabin pressure altitudes below 15,000 feet. The number of oxygen outlets need only be suffcient to administer oxygen to the percentage of passengers indicated by the operating rules; however, it is desirable in fixed systems to provide an outlet for each seat to enable a crew member to readily administer oxygen to any passenger requiring it. If this is not accomplished, it is recommended that provision be made by means of portable equipment, extension tubing, or otherwise to reduce

the probability of having to move any passenger who may require the administration of oxygen. At cabin pressure altitudes above 15,000 feet the operating regulations require that oxygen be furnished to all of the passengers, in which case an outlet should be provided for each seat. (See also § 4b.651-5 concerning portable walk-around units.)

(c) Line supports. In a fixed installation, the oxygen lines should be supported to prevent excessive vibration and should be kept clear of the airplane structure or any other lines as a protection against chafing. Supports approximately every 24 inches along the length of the line should be adequate.

(d) Shut-off valves. System shut-off valves should be accessible in flight and should be installed as close as practicable to the cylinders in order to minimize the possibility of oxygen escape due to leakage or damage of lines between cylinders and valves.

(e) Cylinder supports. The supporting brackets for all cylinders should be capable of withstanding the inertia forces stipulated under the emergency landing conditions. (See § 4b.260.) [Supp. 21, 17 F. R. 11713, Dec. 24, 1952] § 4b.651-5 Portable walk-around oxygen units (FAA policies which apply to § 4b.651).

(a) Portable walk-around oxygen units of the continuous flow, diluter-demand and straight demand types may be used to satisfy part or all of crew or passenger breathing requirements.

(b) Each portable oxygen unit should be considered as a complete oxygen system and any regulations or pertinent interpretative material relative to oxygen systems should also be applicable to each portable unit.

(c) The supporting brackets for portable oxygen units should be capable of withstanding the inertia forces stipulated under the emergency landing conditions. (See § 4b.260.)

[Supp. 21, 17 F. R. 11713, Dec. 24, 1952] § 4b.651-6 Oxygen pressure gage (FAA policies which apply to § 4b.651(a)).

At least one pressure gage, which can be observed by a flight crew member during flight, should be installed to indicate the pressure in each source of oxygen supply.

[Supp. 21, 17 F. R. 11713, Dec. 24, 1952]