S=NXFXTX2.12 S supply of oxygen required in cubic N=number of oxygen users. T-time in hours at the cabin altitude 2.12= multiplying factor for converting the oxygen mass flow from liters per minute to cubic feet per hour. NOTE: In computing the supply of oxygen for a given installation, those operating rules of the Civil Air Regulations which specify the amount of oxygen to be carried for operating at various altitudes should be considered. (b) (1) The intent of § 4b.651 (b) is to insure that for each oxygen iser, a partial pressure of 149 mm Hg of oxygen is maintained in the inspired air at a breathing rate of 15 lpm BTPD, at altitudes up to 25,000 feet. The rates of flow specified in Figure 4b-21 satisfy the intent of § 4b.651 (b) and constitute the values for "F"" in the supply equation when there is no loss of bottle oxygen from the system (including the mask) when a 15 lpm BTPD breathing rate is maintained. (2) The oxygen mask, since it constitutes part of the system, will influence the value of "F". Continuous flow masks with rebreather bags which are currently standard types for aviation usage are satisfactory with the flow rates indicated by Fig. 4b-21. Where a receptacle or mask design differs from these, the manufacturer should be requested to supply information concern ing the flow rate necessary to maintain the 149 mm Hg partial pressure at a 15 1pm BTPD breathing rate. If the actual mass flow is greater than the minimum required, then the higher flow rate should be used as the value for "F". (3) It is possible that certain automatic continuous flow regulators will furnish oxygen flows in excess of the minimum required; in this case, the actual flow rates should be used as the values for "F". NOTE: (1) BTPD signifies gas at 37° C. (body temperature), ambient pressure, dry. (2) STPD signifies gas at 0° C., 760 mm Hg., dry. [Supp. 24, 19 F. R. 4467, July 20, 1954] § 4b.651-8 Supply required for diluterdemand system (FAA policies which apply to § 4b.651). (a) Tests conducted by the Armed Forces on currently available diluterdemand regulators indicate that some types deliver more oxygen than is required by Fig. 4b-21. Consequently, in computing the supply required for a diluter-demand system, the flow characteristics at various altitudes should be obtained from the manufacturer of the regulator. Where this information is not available, the values listed in the following table may be used for Air Force-Navy approved diluter-demand regulators: Altitude in feet: 8,000 10,000 15,000 20,000 25,000 Flow per person in LPM (STPD)1 1.90 1.90 2.10 2.50 4.10 1 These values are based on tests on a large group of men using the equipment at the altitude specified. The values listed are those calculated to completely protect 95 percent of the population. (b) The formula outlined in § 4b.6517 (a) may be used in computing the supply of oxygen for supplementary breathing purposes. [Supp. 24, 19 F. R. 4467, July 20, 1954] § 4b.651-9 Requirements for approval of oxygen systems. (FAA policies which apply to § 4b.651(b). Prior to the approval of an oxygen system, the system should be examined to determine that the flow of oxygen through each outlet is at least equal to the minimum required by § 4b.651(b) at all altitudes for which the aircraft is cer tificated. This can be accomplished by one of the following methods or by any other satisfactory procedure: (a) (1) In a continuous flow system when the calibration (inlet pressure vs. flow) of the orifices used at the plug-in outlets is known, the pressure in the low pressure distribution line can be measured at the point which is subject to the greatest pressure drop. This should be done with oxygen flowing from all outlets. The pressure thus measured should indicate a flow equal to or greater than the minimum flow required. (2) In lieu of the above procedure, the flow of oxygen through the outlet which is subject to the greatest pressure drop may be measured. This should be accomplished with all other outlets open. Gas meters, rotometers, or other suitable means may be used to measure flows. (3) The measurement of oxygen flows in a continuous flow system which uses a manually adjusted regulator can be accomplished at sea level. However, in a continuous flow system which uses an automatic type regulator, it may be necessary to check the flows at the maximum altitude which will be encountered during the normal operation of the aircraft. The manufacturer of the particular continuous flow regulator being used should be able to furnish data on the operating characteristics of the regulator from which it can be determined whether flight tests are necessary. (b) (1) The checking of the amount of oxygen flow through the various outlets in a diluter-demand or straight demand system is not necessary since the flow characteristics of the particular regulator being used may be obtained from the manufacturer of the regulator. However, in such systems the availability of oxygen to each regulator should be checked as follows: (i) Turn the lever of the diluterdemand regulator to the "100% OXYGEN" position and inhale through the tube via the mask to determine whether the regulator valve and the flow indicator are operating. Deficient units should be replaced. [Supp. 21, 17 F. R. 11713, Dec. 24, 1952] demand systems are used for supplementary breathing purposes, each crew member should have an individual flow indicator for determining oxygen flow or the operator may establish a suitable procedure for determining oxygen flow and should include such procedures in the Airplane Flight Manual. (2) If flow indicators are used, the indicator for any particular crew member should be located so as to be easily observed by him while he is at his crew station. Acceptable flow indicators are listed in § 4b.651-12. (3) If a suitable procedure is to be used for determining oxygen flow in non-pressurized cabin aircraft, the procedure should include initial and periodic checking of the oxygen flow by each crew member by any acceptable method. Some of the acceptable methods are described under § 4b.651-11 (a) and (b). In pressurized cabin aircraft when supplementary oxygen is required immediately following cabin pressurization failure, positive means for determining flow under emergency conditions should be established which would not involve delay or activities which would interfere with a flight crew member's performance of his primary duties. Since utilizing one of the methods for determining oxygen flow permitted for supplementary breathing equipment described under § 4b.651-11 (a) and (b) involves some time delay a flight crew member could don his protective breathing equipment following a pressurization failure because with such equipment oxygen flow is immediately apparent. As soon as some degree of control of the emergency has been established and sufficient time is available to determine oxygen flow by one of the methods mentioned above, he could change over to his supplementary breathing equipment. (b) Protective breathing systems. No flow indicators are required in protective breathing systems since with these systems the lack of oxygen flow would be immediately evidenced by the oxygen user's inability to inhale while wearing mask. [Supp. 24, 19 F. R. 4467, July 20, 1954] § 4b.651-11 Means for determining oxygen flow to passengers (FAA policies which apply to § 4b.651(e)). Each passenger may be supplied with an individual flow indicator of a type specified in § 4b.641-12 or the operator involved may establish a suitable procedure for checking the oxygen flow to each oxygen user. Procedures which utilize the following means for checking oxygen flow to such user will be satisfactory. (a) In the case where a continuous flow system is used the means may be the observing of the rebreather bag on each continuous flow mask by a trained crew member. If oxygen flow is occurring the rebreather bag will continue to expand when the oxygen user periodically refrains from exhaling when the bag is empty or partially empty, or in cases where high oxygen flows are occurring, the rebreather bag may not empty completely during normal inhalation. Any alternate method of checking oxygen flow may be used providing positive indication of flow is given. For example, prior to giving a mask to a passenger, the crew member may find it expedient to feel the flow of oxygen at the oxygen outlet in the mask or to constrict the tubing and listen to audible sounds characteristic of gas flow. If a listening test is employed to determine the flow of oxygen, it should be demonstrated in flight that the test is satisfactory. (b) In the case where a diluterdemand system is used, the procedure may be checking of the oxygen flow by a trained crew member by momentarily moving the regulator lever to "AUTOMIX OFF" (100% OXYGEN) while the mask is being worn. Lack of oxygen flow will be immediately evidenced by the user's inability to inhale while wearing his mask. (c) The oxygen flow to each passenger should be checked when the passenger is first given oxygen and at subsequent intervals if the circumstances prevailing at the time indicate such a check is desirable. (d) Any crew member assigned by an air carrier for the performance of duty on the aircraft during flight may check the oxygen flow to the passengers if trained to do so. [Supp. 21, 17 F. R. 11714, Dec. 24, 1952] § 4b.651-12 Types of flow indicators (FAA policies which apply to $ 4b.651(e)). A pith ball flow indicator, vane, or wheel anemometer, lateral pressure indicator which fluctuates with changes in flow or any other satisfactory flow indi cator may be used in a continuous flow type system. An Air Force-Navy flow indicator or equivalent may be used in a diluter-demand type system. Each flow indicator should give positive indication when oxygen flow is occurring. [Supp. 21, 17 F. R. 11714, Dec. 24, 1952] § 4b.652 Engine-driven accessories. Engine-driven accessories, essential to safe operation of the airplane shall be so distributed among two or more engines that the failure of any one engine will not impair the safe operation of the airplane. § 4b.653 Hydraulic systems; strength. (a) Structural loads. All elements of the hydraulic system shall be designed to withstand, without detrimental permanent deformation, all structural loads which may be imposed simultaneously with the maximum hydraulic loads occurring in operation. (b) Proof pressure tests. All elements of the hydraulic system shall be tested to a proof pressure of 1.5 times the maximum pressure to which the part will be subjected in normal operation. In such test no part of the hydraulic system shall fail, malfunction, or suffer detrimental deformation. (c) Burst pressure strength. Individual hydraulic system elements shall be designed to withstand pressures which are sufficiently increased over the pressures prescribed in paragraph (b) of this section to safeguard against rupture under service conditions. NOTE: The following pressures, in terms of percentage of maximum operating pressure for the particular element, in most instances are sufficient to insure against rupture in service: 250 percent in units under oil pressure, 400 percent in units containing air and oil under pressure and in lines, hoses, and fittings, 300 percent in units of system subjected to back pressure. [Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952] § 4b.654 Hydraulic systems; design. (a) Pressure indication. A means shall be provided to indicate the pressure in each main hydraulic power system. (b) Pressure limiting provisions. Provision shall be made to assure that pressures in any part of the system will not exceed a safe limit above the maximum operating pressure of the system and to insure against excessive pressures resulting from fluid volumetric changes in all lines which are likely to remain closed long enough for such changes to take place. In addition, consideration shall be given to the possible occurrence of detrimental transient (surge) pressures during operation. (c) Installation. Hydraulic lines, fittings, and components shall be installed and supported to prevent excessive vibration and to withstand inertia loads. All elements of the installation shall be protected from abrasion, corrosion, and mechanical damage. (d) Connections. Flexible hose, or other means of providing flexibility, shall be used to connect points in a hydraulic fluid line between which there is relative motion or differential vibration. [Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952] § 4b.655 Hydraulic system fire protec tion. When flammable type hydraulic fluid is used, the hydraulic system shall comply with the provisions of §§ 4b.385, 4b.481, 4b.482, and 4b.483. [Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952] § 4b.658 Vacuum systems. (a) Means, in addition to the normal pressure relief, shall be provided to relieve automatically the pressure in the discharge lines from the vacuum pump, if the delivery temperature of the air reaches an unsafe value. (b) Vacuum system lines and fittings on the discharge side of the pump which might contain fiammable vapors or fluids shall comply with § 4b.483 if they are located in a designated fire zone. Other vacuum system components located in designated fire zones shall be fire-resistant. [Amdt. 4b-6, 17 F. R. 1099, Feb. 5, 1952] § 4b.659 Equipment incorporating high energy rotors. Equipment incorporating high energy rotors shall be demonstrated as capable of containing a failed rotor or shall be so located that failure will not affect the ability of the airplane to continue safe flight. [Amdt. 4b-8, 23 F. R. 2591, Apr. 19, 1958] § 4b.660 Draining of fluids subject to freezing. When liquids subject to freezing are drained overboard either in flight or during ground operation, drains shall be located and designed to prevent the for § 4b.700-1 Automatic propeller feathering operating limitations and information (FAA policies which apply to § 4b.700). (a) All limitations on the use of automatic feathering system, including flight conditions when the system must be operative or inoperative should be determined and noted when appropriate. (b) Any placards found necessary should be provided in the airplane. (c) A complete statement of operating limitations and instructions for the use of the system should be included in the Airplane Flight Manual. (d) If certification is desired both with and without the feathering system operative, two corresponding sets of performance data properly identified should be included in the Airplane Flight Manual. (See also § 4b.10-2.) [Supp. 23, 19 F. R. 1818, Apr. 2, 1954] OPERATING LIMITATIONS § 4b.710 Air-speed limitations; general. When air-speed limitations are a function of weight, weight distribution, altitude, or Mach number, the values corresponding with all critical combinations of these values shall be established. § 4b.711 Never-exceed speed VNE. (a) To allow for possible variations in the airplane characteristics and to minimize the possibility of inadvertently exceeding safe speeds, the never-exceed speed VNE shall be a speed established sufficiently below the lesser of: (1) The design dive speed VD chosen in accordance with § 4b.210 (b) (5), or (2) The maximum speed demonstrated in flight in accordance with § 4b.190. (b) In the absence of a rational investigation, the value of VNE shall not exceed 0.9 times the lesser of the two speeds referred to in paragraph (a) of this section. NOTE: Where speeds are limited by compressibility effects, this section is intended to provide an adequate margin between MNE and the lowest of the following Mach values: MD, MDF, or the Mach number where adverse flight characteristics, such as the following, occur: Undue reduction in ability to recover; rapid or large changes in stability during level flight or recovery which would cause the airplane to exceed structural limits; buffeting so severe as to endanger the structural integrity of the airplane. The speed margin required usually depends upon the effectiveness of the warning provided to the pilots whenever MNE is reached or exceeded, and upon the recovery or speed control characteristics of the airplane. In any case the margin should be sufficient: To enable recovery from mild upsets due to gusts or inadvertent control movements or trim changes; to allow for inadvertent increases in Mach number due to horizontal gusts or temperature inversions; and, for instrument inaccuracies or airplane production differences. The probability of the simultaneous occurrence of the aforementioned speed margin conditions are usually considered, but the effects of all such conditions are not necessarily additive. [15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-3, 21 F. R. 994, Feb. 11, 1956] § 4b.712 Normal operating limit speed VNO. (a) The normal operating limit speed VNO shall be established not to exceed the design cruising speed Vc chosen in accordance with § 4b.210(b) (4) and sufficiently below the never-exceed speed VNE to make it unlikely that VNE would be exceeded in a moderate upset occurring at VNO. (b) In the absence of a rational investigation, the value of Vлo shall not exceed 0.9 times VNE. (c) At altitudes where VNE is limited by compressibility, a spread between VNO and VNE shall not be required; i.e., MNO equal to the lesser of MNE or Mo shall be acceptable. [15 F.R. 3543, June 8, 1950, as amended by Amdt. 4b-2, 20 F.R. 5309, July 26, 1955] The maneuvering speed shall not exceed the design maneuvering speed VA determined in accordance with § 4b.210 (b) (2). § 4b.714 Flap extended speed Vre. (a) The flap extended speed VFE shall be established not to exceed the lesser of: (1) The design flap speed V, chosen in accordance with § 4b.210(b) (1), or (2) The design speed for slipstream effects with flaps in the landing position, chosen in accordance with § 4b.221. (b) The value of VFE established in accordance with paragraph (a) of this section shall not be less than a value which provides a safe speed margin above the stall during approach and landing. (c) It shall be acceptable to establish supplementary values of VFE for other combinations of flap setting, air speed, and engine power, if the structure and the flight characteristics of the airplane have been shown to be satisfactory for such combinations. § 4b.715 Landing gear operating speed V LO. The landing gear operating speed VLO shall be established not to exceed a speed at which it is safe to extend or retract the landing gear as limited by design in accordance with § 4b.334 or by flight characteristics. § 4b.716 Landing gear extended speed V LE. The landing gear extended speed VLB shall be established not to exceed a speed at which it has been shown that the airplane can be safely flown with the landing gear secured in the fully extended position, and for which the structure has been proven in accordance with § 4b.334. § 4b.717 Minimum control speed Vac. (See § 4b.133.) |