(i) In general, industry practice has been to separate and isolate the oxygen system from sources of ignition. Ignition sources include pumps, motors, and electrical equipment associated with the medical installations as well as the aircraft equipment. Further, the manufacturers normally install a pressure relief device with an overboard vent line.
e. Reference. The address for ordering the document listed below can be found in the Appendix to this AC.
The Society of Automotive Engineers (SAE) has aerospace committees that prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook, “1992 SAE Aircraft Oxygen Equipment Handbook,” containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains information that may be of interest to an applicant.
64. SECTION 25.1443 - MINIMUM MASS FLOW OF SUPPLEMENTAL OXYGEN.
a. Rule Text.
(a) If continuous flow equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember may not be less than the flow required to maintain, during inspiration, a mean tracheal oxygen partial pressure of 149 mm. Hg. when breathing 15 liters per minute, BTPS, and with a maximum tidal volume of 700 cc. with a constant time interval between respirations.
(b) If demand equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember may not be less than the flow required to maintain, during inspiration, a mean tracheal oxygen partial pressure of 122 mm. Hg., up 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. In addition, there must be means to allow the crew to use undiluted oxygen at their discretion.
(c) For passengers and cabin attendants, the minimum mass flow of supplemental oxygen required for each person at various cabin pressure altitudes may not be less than the flow required to maintain, during inspiration and while using the oxygen equipment (including masks) provided, the following mean tracheal oxygen partial pressures:
(1) At cabin pressure altitudes above 10,000 feet up to and including 18,500 feet, a mean tracheal oxygen partial pressure of 100 mm. Hg. when breathing 15 liters per minute, BTPS, and with a tidal volume of 700 cc. with a constant time interval between respirations.
(2) At cabin pressure altitudes above 18,500 feet up to and including 40,000 feet, a mean tracheal oxygen partial pressure of 83.8 mm. Hg. when breathing 30 liters 156
per minute, BTPS, and with a tidal volume of 1,100 cc. with a constant time interval between respirations.
(d) If first-aid oxygen equipment is installed, the minimum mass flow of oxygen to each user may not be less than four liters per minute, STPD. However, there may be a means to decrease this flow to not less than two liters per minute, STPD, at any cabin altitude. The quantity of oxygen required is based upon an average flow rate of three liters per minute per person for whom first-aid oxygen is required.
(e) If portable oxygen equipment is installed for use by crewmembers, the minimum mass flow of supplemental oxygen is the same as specified in paragraph
(a) or (b) of this section, whichever is applicable.
b. Intent of Rule. The requirements of this rule provide standards to ensure that oxygen dispensing equipment will protect passengers and crewmembers from the effects of hypoxia.
The requirements for flight crewmembers are provided in terms of mean tracheal partial pressure of oxygen, which is not easily measured in certification testing. Dispensing equipment is, however, designed to provide the required oxygen flow. This equipment is, in most cases, approved through the technical standard order system. Requirements for passenger and cabin crewmember equipment are expressed in terms of oxygen flow rates.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirements in § 4b.651(b) of the CAR were carried over essentially unchanged to § 25.1443 of 14 CFR.
d. Policy/Compliance Methods. There is no written policy or guidance in our files.
e. Reference. The address for ordering the document listed below can be found in the Appendix to this AC.
The Society of Automotive Engineers (SAE) has aerospace committees that prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains valuable information that may be of interest to an applicant.
65. SECTION 25.1445 - EQUIPMENT STANDARDS FOR THE OXYGEN DISTRIBUTING SYSTEM.
a. Rule Text.
(a) When oxygen is supplied to both crew and passengers, the distribution system must be designed for either-
(1) A source of supply for the flight crew on duty and a separate source for the passengers and other crewmembers; or
(2) A common source of supply with means to separately reserve the minimum supply required by the flight crew on duty.
(b) Portable walk-around oxygen units of the continuous flow, diluter-demand, and straight demand kinds may be used to meet the crew or passenger breathing requirements.
b. Intent of Rule. This rule addresses the oxygen distribution system and does not address oxygen dispensing equipment (masks), the standards for which are addressed in § 25.1447.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirements in § 4b.651(c) of the CAR were carried over essentially unchanged to § 25.1445 of 14 CFR, except for the standards on potable walk-around units that are found in § 25.1445(b).
d. Policy/Compliance Methods. There is no written policy or guidance in our files.
e. Reference. The address for ordering the document listed below can be found in the Appendix to this AC.
The Society of Automotive Engineers (SAE) has aerospace committees that prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook, “1992 SAE Aircraft Oxygen Equipment Handbook,” containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains information that may be of interest to an applicant.
66. SECTION 25.1447 - EQUIPMENT STANDARDS FOR OXYGEN DISPENSING UNITS.
a. Rule Text.
If oxygen dispensing units are installed, the following apply:
(a) There must be an individual dispensing unit for each occupant for whom supplemental oxygen is to be supplied. Units must be designed to cover the nose and mouth and must be equipped with a suitable means to retain the unit in 158
position on the face. Flight crew masks for supplemental oxygen must have provisions for the use of communication equipment.
(b) If certification for operation up to and including 25,000 feet is requested, an oxygen supply terminal and unit of oxygen dispensing equipment for the immediate use of oxygen by each crewmember must be within easy reach of that crewmember. For any other occupants, the supply terminals and dispensing equipment must be located to allow the use of oxygen as required by the operating rules in this chapter.
(c) If certification for operation above 25,000 feet is requested, there must be oxygen dispensing equipment meeting the following requirements:
(1) There must be an oxygen dispensing unit connected to oxygen supply terminals immediately available to each occupant, wherever seated, and at least two oxygen dispensing units connected to oxygen terminals in each lavatory. The total number of dispensing units and outlets in the cabin must exceed the number of seats by at least 10 percent. The extra units must be as uniformly distributed throughout the cabin as practicable. If certification for operation above 30,000 feet is requested, the dispensing units providing the required oxygen flow must be automatically presented to the occupants before the cabin pressure altitude exceeds 15,000 feet. The crew must be provided with a manual means of making the dispensing units immediately available in the event of failure of the automatic system.
(2) Each flight crewmember on flight deck duty must be provided with a quickdonning type oxygen dispensing unit connected to an oxygen supply terminal.
This dispensing unit must be immediately available to the flight crewmember when seated at his station, and installed so that it:
(i) Can be placed on the face from its ready position, properly secured, sealed, and supplying oxygen upon demand, with one hand, within five seconds and without disturbing eyeglasses or causing delay in proceeding with emergency duties; and
(ii) Allows, while in place, the performance of normal communication functions.
(3) The oxygen dispensing equipment for the flight crewmembers must be:
(i) The diluter demand or pressure demand (pressure demand mask with a diluter demand pressure breathing regulator) type, or other approved oxygen equipment shown to provide the same degree of protection, for airplanes to be operated above 25,000 feet.
(ii) The pressure demand (pressure demand mask with a diluter demand pressure breathing regulator) type with mask-mounted regulator, or other approved oxygen equipment shown to provide the same degree of protection, for airplanes operated at altitudes where decompressions that are not extremely improbable may expose the flightcrew to cabin pressure altitudes in excess of 34,000 feet.
(4) Portable oxygen equipment must be immediately available for each cabin attendant.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-41, 42 FR 36971, Jul. 18, 1977; Amdt. 25-87, 61 FR 28696, Jun. 5, 1996]
b. Intent of Rule. This rule addresses the oxygen dispensing units, including oxygen masks and regulators, and do not address oxygen distributing systems, the standards for which are addressed in § 25.1445.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). Many of the requirements in § 4b.651(d) of the CAR for oxygen dispensing units were carried over essentially unchanged to § 25.1447 of 14 CFR.
(1) Amendment 25-41 (July 18, 1977) added requirements for a manual means for the crew to make the dispensing units available in the event of a failure of the automatic means, and that the masks for use by the flight crewmembers be of the quick donning type.
(2) Amendment 25-87 (June 5, 1996) added flightcrew oxygen equipment requirements for a pressure demand type with mask-mounted regulator, or other approved equipment, for airplanes operated at altitudes where decompressions that are not extremely improbable may expose the flightcrew to cabin pressure altitudes in excess of 34,000 feet.
d. Policy/Compliance Methods. For guidance on compliance with this requirement, refer to the preamble of this rule and the following information.
(1) Oxygen Equipment for Forward Observer's Position. The following policy was extracted from an FAA memorandum dated February 1, 1988, that was written to provide guidance for certification of forward observer's oxygen equipment.
(a) The requirements for a forward observer's seat are contained in § 25.785(k), § 121.581(a), § 125.317(b), and § 135.75(b). In parts 121, 125, and 135 of 14 CFR, there is no specific list of required equipment for the first observer's seat, but rather a general statement that the required equipment would be "determined by the Administrator." The FAA considers a representative of the Administrator, occupying the first observer's seat and performing official duties, to be a required crewmember. This designation also applies to a company check airman, or other person performing official duties relating to the performance of the crew or operation of the airplane. This person would be expected to interact with the captain and other flight crewmembers, in addition to his or her normal duties relating to enroute inspection and surveillance. For these reasons, it is important that the occupant of the observer seat be provided with the equipment necessary to perform his or her function, e.g., oxygen, protective breathing equipment, and communication via a radio and interphone panel which is the same type equipment provided to the flightcrew.
(b) Section 25.785(l) does not specify what type of equipment must be provided at the observer seat as part of the type design. The rule states, “Each forward observer’s seat required by the operating rules must be shown to be suitable for use in conducting the necessary enroute inspection.” Section 25.785(l) has been interpreted to allow the use of passenger-type oxygen equipment, provided that the airplane in question is not to be used in Part 121, 125, or 135 operation. If the airplane is to be so used, the oxygen, communication, and protective 160
breathing requirements stated above must be provided. If the airplane is not to be used in parts 121, 125, or 135 operation (i.e., in Part 91 operation), installation of either type of oxygen equipment at the first observer's seat is adequate to show compliance with the requirements of § 25.1441, Oxygen Equipment and Supply, and installation of communication equipment and protective breathing equipment would be optional.
(c) The duration of oxygen supply should be commensurate with the crew supply, since protection may be necessary due to a delayed descent following decompression, protective breathing requirements, or other extended usage.
e. References. The addresses for ordering the latest revision of technical standard orders and other referenced documents listed below can be found in the Appendix to this AC.
TSO-C64a, Oxygen Mask Assembly Continuous Flow, Passenger (For Air Carrier Aircraft).
TSO-C78, Crewmember Demand Oxygen Masks.
TSO-C89, Oxygen Regulators, Demand.
TSO-C99, Protective Breathing Equipment.
TSO-C116, Crewmember Protective Breathing Equipment.
The Society of Automotive Engineers (SAE) has aerospace committees which prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook, “1992 SAE Aircraft Oxygen Equipment Handbook,” containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains information that may be of interest to an applicant.
67. SECTION 25.1449 - MEANS FOR DETERMINING USE OF OXYGEN.
a. Rule Text.
There must be a means to allow the crew to determine whether oxygen is being delivered to the dispensing equipment.
b. Intent of Rule. The standards in this section ensure that the flightcrew is able to determine that oxygen is being dispensed properly.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirement in § 4b.651(e) of the CAR that there be a means for the crew to determine that oxygen is being delivered to the dispensing equipment (masks) were carried over essentially unchanged to § 25.1449 of 14 CFR.
d. Policy/Compliance Methods. For guidance on compliance with this requirement, refer to the preamble of this rule and the following information. Compliance with this section is usually 161
accomplished by the use of flow indicators in the oxygen regulators (for flight crewmembers) and in the oxygen tubes leading to the masks (for passenger equipment).
(1) Oxygen Equipment for Observer Position. The following policy was extracted from an FAA letter dated April 19, 1996, in response to an inquiry concerning the requirement for supplemental oxygen flow indication at the observers' stations.
(a) An applicant proposed installing mask-mounted regulators without flow indication at the observers' stations. This configuration has been certified for previous versions of the same airplane model. It was the applicant’s position that the FAA exempts mask-mounted regulators from the § 25.1449 flow indication requirement. They cited FAA Technical Standard Order (TSO) C-89, which exempts mask-mounted regulators from the TSO requirement to provide a means to indicate oxygen flow from the regulator outlet. Although the TSO allows omission of flow indicators for mask-mounted regulators, it is not an authorization to install such items on transport airplanes. However, the FAA reviewed the original certification data for the airplane model in question, and the background of § 25.1449. Based on this review, the FAA determined that installation of the mask-mounted regulators without flow indicators at the observers' stations meets the intent of § 25.1449.
(b) The background for § 25.1449 is found in the FAA Civil Aeronautics Manual (CAM) 4b. Section 25.1449 states: "There must be a means to allow the crew to determine whether oxygen is being delivered to the dispensing equipment." Similarly, § 4b.651 of the Civil Air Regulation (CAR) states: "Means shall be provided to enable the crew to determine whether oxygen is being delivered to the dispensing units." Although flow indicators for each individual passenger or flight crew station represent one method of compliance, policy guidance provided in § 4b.651-10 of the CAR (for crew systems) and § 4b.651-11 of the CAR (for passenger systems) allows operators to establish procedures for checking the oxygen flow to individual oxygen users. For passenger diluter-demand systems, § 4b.651-11 of the CAR states that the procedure may be "checking of the oxygen flow by a trained crewmember by momentarily moving the regulator lever to Automix ‘OFF’ (100% OXYGEN) while the mask is being worn."
Lack of oxygen flow would be "immediately evidenced by the user's inability to inhale while wearing his mask."
(c) The FAA is satisfied that § 25.1449 does not specifically require flow indicators at each mask. Although these indicators are generally provided, other methods of flow indication are not precluded. Therefore, the FAA is satisfied that flow indicators are not required at the observers' stations for certification, provided that the applicant incorporates suitable design features and procedures to ascertain flow at the observers' stations. On the model in question, supplemental oxygen for the flightcrew and the observers' stations is provided by a common source. Flow of oxygen from the source is split between the flight crew and observers' stations by a "T" fitting. Under normal operations, all cockpit masks are set for "100% OXYGEN." At this setting, lack of flow would be immediately detected by the user. The FAA is requiring incorporation of a preflight check of the observers' masks in the airplane flight manual (AFM).
In addition, a positive indication of flow at the flightcrew stations by the flow indicators installed at those stations would indicate that oxygen is also flowing to the observers' stations. The FAA 162
is satisfied that the system design, the preflight inspection procedure, and flow indicators at the flightcrew stations are adequate to meet the intent of § 25.1449.
(2) Determination of Passenger Oxygen Supply. The following policy was extracted from an FAA memorandum dated January 8, 1996, which addresses compliance with § 25.1449 for a design that will determine, from the flightdeck, that oxygen is flowing to the passenger supplemental oxygen masks. It is noted that 14 CFR does not require a means for the flightcrew to make this determination while on flight deck duty. A number of airplanes have gaseous supplemental oxygen systems which do not have a specific indication of oxygen flow on the flight deck. Compliance with 14 CFR requirements is usually shown through use of a flow indicating device in the oxygen mask tubing. Technical Standard Order TSO-C64a, and the associated Society of Automotive Engineers Aerospace Standard SAE-AS 8025, require a means for the crew to determine that oxygen is flowing. This is usually accomplished with a small device that provides a green indication when the flow rate exceeds 0.5 liters per minute. A cabin crewmember verifies from the indicator whether or not oxygen is flowing. If there are no cabin crewmembers, this would require a flight crewmember to leave their station and check. The FAA has determined that this would not be a viable option during an emergency such as a decompression.
e. References. None.
68. SECTION 25.1450 - CHEMICAL OXYGEN GENERATORS.
a. Rule Text.
(a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction.
(b) Each chemical oxygen generator must be designed and installed in accordance with the following requirements:
(1) Surface temperature developed by the generator during operation may not create a hazard to the airplane or to its occupants.
(2) Means must be provided to relieve any internal pressure that may be hazardous.
(c) In addition to meeting the requirements in paragraph (b) of this section, each portable chemical oxygen generator that is capable of sustained operation by successive replacement of a generator element must be placarded to show-
(1) The rate of oxygen flow, in liters per minute;
(2) The duration of oxygen flow, in minutes, for the replaceable generator element; and
(3) A warning that the replaceable generator element may be hot, unless the element construction is such that the surface temperature cannot exceed 100 degrees F.
[Amdt. 25-41, 42 FR 36971, Jul. 18, 1977]
b. Intent of Rule. The standards in this rule ensure that chemical oxygen generators safely provide oxygen.
c. Background. The standards in this section address chemical oxygen generators. This subject was not addressed in either part 4b of the CAR or part 25 when it was originally codified.
This section was added at Amendment 25-41, July 18, 1977.
d. Policy/Compliance Methods. There is no written policy or guidance in our files.
e. Reference. The address for ordering the latest revision of the document listed below can be found in the Appendix to this AC.
The Society of Automotive Engineers (SAE) has aerospace committees that prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook, “1992 SAE Aircraft Oxygen Equipment Handbook,” containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains information that may be of interest to an applicant.
69. SECTION 25.1453 PROTECTION OF OXYGEN EQUIPMENT FROM RUPTURE.
a. Rule Text.
Oxygen pressure tanks, and lines between tanks and the shutoff means, must be-
(a) Protected from unsafe temperatures; and
(b) Located where the probability and hazards of rupture in a crash landing are minimized.
b. Intent of Rule. This rule ensures that the oxygen equipment is not exposed to unsafe temperatures and minimizes the possibility of rupture in the event of a crash landing.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirements in § 4b.651(g) of the CAR were carried over essentially unchanged to § 25.1453 of 14 CFR.
d. Policy/Compliance Methods. For guidance on compliance with this requirement, refer to the preamble of this rule and the following information.
(1) Flexible Plastic Oxygen Lines. The following policy was extracted from an FAA memorandum dated December 27, 1983, to provide guidance regarding the use of flexible plastic tubing for oxygen distribution lines. While this guidance was generated for Part 23 airplanes, it is equally applicable for part 25 airplanes.
(a) The FAA has determined that the use of plastic lines for an oxygen distribution system that is operating under continuous pressure is not acceptable for certification in Part 23 airplanes.
(b) Lines constructed of combustible materials, including nylon, polyvinylchloride (PVC) and Teflon, may be used in oxygen lines which are pressurized only when cabin depressurization occurs. The following precautions should be taken when using such lines in the oxygen system:
1 Swaged metal type end fittings should be used to prevent leakage from cold flow.
2 Lines should be protected from abrasion by use of a reinforcing sleeving of fabric braid.
3 Precautions should be taken to route such lines away from areas where they might be subjected to elevated temperatures, electrical arcing (relays and switches) and flammable fluids.
4 Refer to Advisory Circular (AC) 43.13-2A, Chapter 6, for additional guidance material.
(2) Use of Plastic Oxygen Lines. The following policy was extracted from an FAA memorandum dated October 28, 1983, and addresses the use of plastic or nylon tubing as oxygen lines.
(a) Tubing in the fuselage for high or low pressure oxygen systems that are located behind liners or in the walls of the fuselage are typically made of rigid stainless steel (for high pressure) or aluminum (for low pressure). Synthetic flexible lines connecting the oxygen mask to the oxygen distribution system have been accepted. Swaged metal end fitted PVC tubing, covered with a synthetic braid (for abrasion resistance and strength), should be used between the aluminum low pressure distribution line and the passenger service unit manifold of many large transports. These tubes and aluminum line do not contain oxygen until a depressurization occurs. Then, the pressure is low and for a short duration. These hoses meet the interior burn requirements.
(b) Synthetic lines such as plastic or nylon cannot be recommended for oxygen high or low pressure lines that will be exposed to a continuous pressure (i.e., as opposed to pressurized when needed). These materials can cold flow. Care must be taken in the selection of the fitting design for exposures of even short duration.
(c) In addition to cold flow, polyethylene and nylon will lose strength with increasing temperature. These materials are much more susceptible to combustion in the presence of oxygen than either stainless steel or aluminum. For these reasons, the FAA 165
considers polyethylene or nylon tubing inappropriate and unsafe for oxygen lines that are subjected to continuous oxygen pressure.
e. Reference. The address for ordering the document listed below can be found in the Appendix to this AC.
The Society of Automotive Engineers (SAE) has aerospace committees that prepare documents reflecting industry standards and practices. The SAE A-10 Committee, Aircraft Oxygen Equipment, has prepared a handbook, “1992 SAE Aircraft Oxygen Equipment Handbook,” containing all Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports related to oxygen equipment published by SAE. While not regulatory in nature, this handbook contains information that may be of interest to an applicant.
70. SECTION 25.1455 - DRAINING OF FLUIDS SUBJECT TO FREEZING.
a. Rule Text.
If fluids subject to freezing may be drained overboard in flight or during ground operation, the drains must be designed and located to prevent the formation of hazardous quantities of ice on the airplane as a result of the drainage.
[Amdt. 25-23, 35 FR 5680, Apr. 8, 1970]
b. Intent of Rule. This rule addresses fluids subject to freezing that normally drain from the airplane either in flight or during ground operation. The intent is to prevent damage to the airplane when the ice disengages and falls free. This section addresses "gray" water from the sinks and drains in galleys and lavatories. Section 25.1455 does not apply to lavatory drain systems that are normally drained when the airplane is parked, rather than being in "ground operation." This requirement is usually met by designing the drain masts (usually heated to prevent the fluid from freezing) so that the fluid does not impact the airframe or engines when it is draining.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirements in section 4b.660 of the CAR were carried over to § 25.1455 of 14 CFR.
(1) Amendment 25-23 (April 8, 1970) changed the intent of the rule from preventing the formation of ice to preventing the formation of hazardous quantities of ice on the airplane as a result of drainage.
d. Policy/Compliance Methods. There is no written policy or guidance in our files.
e. Reference. The address for ordering the latest revision of the advisory circular listed below can be found in the Appendix to this AC.
AC 25.1455-1, Waste Water/Potable Water Drain System Certification Testing.
71. SECTION 25.1461 - EQUIPMENT CONTAINING HIGH ENERGY ROTORS.
a. Rule Text.
(a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section.
(b) High energy rotors contained in equipment must be able to withstand damage caused by malfunctions, vibration, abnormal speeds, and abnormal temperatures.
In addition-
(1) Auxiliary rotor cases must be able to contain damage caused by the failure of high energy rotor blades; and
(2) Equipment control devices, systems, and instrumentation must reasonably ensure that no operating limitations affecting the integrity of high energy rotors will be exceeded in service.
(c) It must be shown by test that equipment containing high energy rotors can contain any failure of a high energy rotor that occurs at the highest speed obtainable with the normal speed control devices inoperative.
(d) Equipment containing high energy rotors must be located where rotor failure will neither endanger the occupants nor adversely affect continued safe flight.
[Amdt. 25-41, 42 FR 36971, Jul. 18, 1977]
b. Intent of Rule. This rule ensures that failures of high energy rotating equipment will not adversely affect systems, structure, or occupants in the event that the rotating components fail at high speeds. Some of the equipment that contains high energy rotors are turbine engine starters, air cycle machines, air driven hydraulic pumps, cooling fans for galley equipment and electronic bays, cabin ventilation recirculation fans, and high speed electrically driven hydraulic pumps.
This section does not pertain to equipment covered by Subpart E, Propulsion, such as engines and auxiliary power units, which are covered by the provisions of § 25.903(d).