that the smoke generator tends to direct smoke toward the top of the compartment, which could result in earlier detection times than would be the case if a cargo fire actually occurred (the objective of the generated smoke is to simulate natural bouyancy, not necessarily the upward velocity). It was noted that there had been no certification tests conducted using the applicant's smoke generator with a deflector hat in place. However, a deflector hat was informally tested during a certification flight test, and the FAA decided to require the use of a smoke deflector for the tobacco generator for any future certification flight tests that involved demonstrating compliance with the provisions of § 25.858.
(h) The FAA noted in our response to the third proposal, paragraph (d) above, regarding approval of continuous smoke generation until detection and allowing "averaging" the detection times to give a one minute overall average for all positions tested, that " Such a finding would not be in accordance with the rule as issued." The applicant expressed the opinion that the § 25.858 wording "...within one minute after the start of a fire" was not adequately defined in the rule. Demonstration of compliance for smoke detection systems, whether the requirement is the previous 5 minute standard per policy or the 1 minute provision in § 25.858, has always been accomplished by measuring the time from smoke generator "ON" until detection. We did not anticipate any change in this policy. If this were not the case, the period of time during which the tobacco charge is being ignited with a torch would be included in the time for detection. For the tobacco generator, the "ON" time is when the tobacco basket is placed in the generator and the fan turned on. For a theatrical smoke generator, the "ON" time is when the switch is turned on. It is recognized that a theatrical smoke generator may have a built in time delay (by design) between the "switch on" event and when the smoke begins to exit; the cognizant ACO engineer needs to make that determination. Such a time differential may be negligible or not measurable.
(4) William J. Hughes Technical Center Research and Development. The FAA Technical Center is currently conducting a research and development (R&D) program to help standardize fire detection certification methods. When this R&D effort is complete, it is intended to revise AC 25-9A to provide more objective criteria for smoke/fire detection certification. The above Policy/Compliance Methods will be subject to change and/or incorporation into the revision to AC 25-9A in the future.
e. References. The addresses for ordering the latest revision of advisory circulars and other referenced documents listed below can be found in the Appendix to this AC.
AC 25-9A - Smoke Detection, Penetration, and Evacuation tests and related flight manual Emergency Procedures.
AC 25-17 - Transport Airplane Cabin Interiors Crashworthiness Handbook FAA Video, Smoke Quantities to Certify Smoke Detection Systems in Cargo Areas.
40. SECTION 25.863 - FLAMMABLE FLUID FIRE PROTECTION.
a. Rule Text.
(a) In each area where flammable fluids or vapors might escape by leakage of a fluid system, there must be means to minimize the probability of ignition of the fluids and vapors, and the resultant hazards if ignition does occur.
(b) Compliance with paragraph (a) of this section must be shown by analysis or tests, and the following factors must be considered:
(1) Possible sources and paths of fluid leakage, and means of detecting leakage.
(2) Flammability characteristics of fluids, including effects of any combustible or absorbing materials.
(3) Possible ignition sources, including electrical faults, overheating of equipment, and malfunctioning of protective devices.
(4) Means available for controlling or extinguishing a fire, such as stopping flow of fluids, shutting down equipment, fireproof containment, or use of extinguishing agents.
(5) Ability of airplane components that are critical to safety of flight to withstand fire and heat.
(c) If action by the flight crew is required to prevent or counteract a fluid fire
(e.g., equipment shutdown or actuation of a fire extinguisher) quick acting means must be provided to alert the crew.
(d) Each area where flammable fluids or vapors might escape by leakage of a fluid system must be identified and defined.
[Amdt. 25-23, 35 FR 5676, Apr. 8, 1970, as amended by Amdt. 25-46, 43 FR 50597, Oct. 30, 1978]
b. Intent of Rule. The intent of this rule is to minimize the probability of ignition of flammable fluid or vapor leakage in any area where they may exist and, in case of ignition, to 114
minimize the resultant hazard to the aircraft. The definition in 14 CFR 1.1 says "Flammable, with respect to a fluid or gas, means susceptible to igniting readily or to exploding. Examples are aviation jet fuel, hydraulic fluid, and oxygen. Hydraulic equipment, e.g., pumps are qualified per airplane and engine manufacturers' specifications, (SAE) industry standards and/or military standards addressing issues of bonding and grounding, flame and arc resistance, explosion proofing, dielectric strength and case drain temperature limits.
c. Background. For guidance on compliance with this requirement, refer to Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 3, section 1.
d. Policy/Compliance Methods. For guidance with this requirement, refer to Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 3, section 1. Section 25.1435(c), Hydraulic systems-fire protection, requires compliance with § 25.863.
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-XX, Propulsion Systems Handbook.
41. SECTION 25.869 - FIRE PROTECTION SYSTEMS.
a. Rule Text.
(a) Electrical system components:
(1) Components of the electrical system must meet the applicable fire and smoke protection requirements of 25.831(c) and 25.863.
(2) Electrical cables, terminals, and equipment in designated fire zones, that are used during emergency procedures, must be at least fire resistant.
(3) Main power cables (including generator cables) in the fuselage must be designed to allow a reasonable degree of deformation and stretching without failure and must be-
(i) Isolated from flammable fluid lines; or
(ii) Shrouded by means of electrically insulated, flexible conduit, or equivalent, which is in addition to the normal cable insulation.
(4) Insulation on electrical wire and electrical cable installed in any area of the fuselage must be self-extinguishing when tested in accordance with the applicable portions of Part I, appendix F of this Part.
(b) Each vacuum air system line and fitting on the discharge side of the pump that might contain flammable vapors or fluids must meet the requirements 25.1183 if the line or fitting is in a designated fire zone. Other vacuum air systems components in designated fire zones must be at least fire resistant.
(c) Oxygen equipment and lines must-
(1) Not be located in any designated fire zone,
(2) Be protected from heat that may be generated in, or escape from, any designated fire zone, and 115
(3) Be installed so that escaping oxygen cannot cause ignition of grease, fluid, or vapor accumulations that are present in normal operation or as a result of failure or malfunction of any system.
[Amdt. 25-72, 55 FR 29784, Jul. 20, 1990]
b. Intent of Rule. The intent of this rule is to minimize the probability of fire damage and to assure critical components of the electrical system, vacuum air system, and oxygen equipment and lines maintain the capability needed to complete safe flight and landing following a fire.
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). Section 4b.626 of the CAR became § 25.1359 of 14 CFR for electrical system fire and smoke protection; section 4b.658 of the CAR became §§ 25.1433(b) and 25.1433(c) of 14 CFR for vacuum air system line and fittings fire protection; and § 4b.651(f) of the CAR became § 25.1451 of 14 CFR for oxygen equipment and lines fire protection..
(1) Amendment 25-72 (July 20, 1990) consolidated all fire protection requirements for electrical, vacuum, and oxygen systems and transferred to § 25.869 “Fire protection: systems.”
Section 25.1359 became § 25.869(a) except for test acceptance criteria which was transferred to Appendix F. Sections 25.1433(b) and (c) were combined as §§ 25.869(b) and 25.1451 became § 25.869(c). Minor editorial changes were also made as necessary.
d. Policy/Compliance Methods: For guidance on compliance with this requirement, refer to the preamble of this rule and the following information. For policy and guidance on § 25.869(a), electrical system components, refer to Advisory Circular (AC) 25-16, AC 25-17 (section 25.1359, paragraph 781), and Appendix F to part 25. For policy and guidance on § 25.869(b), vacuum air systems, refer to the Propulsion Systems Handbook, section 25.1183.
For policy and guidance on § 25.869(c), oxygen equipment and lines, see paragraph 115. d.(3)(e) of this document and AC 25-17, section 25.1451, par 1011.
e. References. The address for ordering the latest revision of the advisory circulars listed below can be found in the Appendix to this AC.
AC 25-16, Electrical Fault and Fire Prevention and Protection.
AC 25-17, Transport Airplane Cabin Interiors Crashworthiness Handbook.
Chapter 2. - POWERPLANT
Section 1. GENERAL
42. SECTION 25.943 - NEGATIVE ACCELERATION.
a. Rule Text.
No hazardous malfunction of an engine, an auxiliary power unit approved for use in flight, or any component or system associated with the powerplant or auxiliary power unit may occur when the airplane is operated at the negative accelerations within the flight envelopes prescribed in 25.333. This must be shown for the greatest duration expected for the acceleration.
[Amdt. 25-40, 42 FR 15043, Mar. 17, 1977]
NOTE: This regulation is the subject of a Federal Aviation Regulations/Joint Aviation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group will be tasked to recommend revisions to § 25.943, paragraphs 25.943 and 25X1315 of the JAR, as well as develop any advisory information if neccessary.
NOTE: For policy and guidance on compliance with this requirement, see Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 4. This regulation applies to hydraulic and pneumatic system components as well. See AC 25-7A, Flight Test Guide for Certification of Transport Category Airplanes, paragraph 101, for flight test procedures. Also see paragraph 25X1315 of the JAR and ACJ 25X1315 for additional information.
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Section 2. FUEL SYSTEM COMPONENTS
43. SECTION 25.1001 - FUEL JETTISONING SYSTEM.
a. Rule Text.
(a) A fuel jettisoning system must be installed on each airplane unless it is shown that the airplane meets the climb requirements of §§ 25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprised of a takeoff, go-around, and landing at the airport of departure with the airplane configuration, speed, power, and thrust the same as that used in meeting the applicable takeoff, approach, and landing climb performance requirements of this part.
(b) If a fuel jettisoning system is required it must be capable of jettisoning enough fuel within 15 minutes, starting with the weight given in paragraph (a) of this section, to enable the airplane to meet the climb requirements of §§ 25.119 and
25.121(d), assuming that the fuel is jettisoned under the conditions, except weight, found least favorable during the flight tests prescribed in paragraph (c) of this section.
(c) Fuel jettisoning must be demonstrated beginning at maximum takeoff weight with flaps and landing gear up and in-
(1) A power-off glide at 1.4 Vs1;
(2) A climb at the one-engine inoperative best rate-of-climb speed, with the critical engine inoperative and the remaining engines at maximum continuous power; and
(3) Level flight at 1.4 Vs1 ; if the results of the tests in the conditions specified in paragraphs (c) (1) and (2) of this section show that this condition could be critical.
(d) During the flight tests prescribed in paragraph (c) of this section, it must be shown that-
(1) The fuel jettisoning system and its operation are free from fire hazard;
(2) The fuel discharges clear of any part of the airplane;
(3) Fuel or fumes do not enter any parts of the airplane; and
(4) The jettisoning operation does not adversely affect the controllability of the airplane.
(e) For reciprocating engine powered airplanes, means must be provided to prevent jettisoning the fuel in the tanks used for takeoff and landing below the level allowing 45 minutes flight at 75 percent maximum continuous power.
However, if there is an auxiliary control independent of the main jettisoning control, the system may be designed to jettison the remaining fuel by means of the auxiliary jettisoning control.
(f) For turbine engine powered airplanes, means must be provided to prevent jettisoning the fuel in the tanks used for takeoff and landing below the level 119
allowing climb from sea level to 10,000 feet and thereafter allowing 45 minutes cruise at a speed for maximum range. However, if there is an auxiliary control independent of the main jettisoning control, the system may be designed to jettison the remaining fuel by means of the auxiliary jettisoning control.
(g) The fuel jettisoning valve must be designed to allow flight personnel to close the valve during any part of the jettisoning operation.
(h) Unless it is shown that using any means (including flaps, slots, and slats) for changing the airflow across or around the wings does not adversely affect fuel jettisoning, there must be a placard, adjacent to the jettisoning control, to warn flight crewmembers against jettisoning fuel while the means that change the airflow are being used.
(i) The fuel jettisoning system must be designed so that any reasonably probable single malfunction in the system will not result in a hazardous condition due to unsymmetrical jettisoning of, or inability to jettison, fuel.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-18, 33 FR 12226, Aug. 30, 1968; Amdt. 25-57, 49 FR 6848, Feb. 23, 1984]
NOTE: This regulation will be the subject of a Federal Aviation Regulations/Joint Aviation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group may recommend revisions to the regulation and any associated advisory material.
NOTE: For policy and guidance on compliance with this requirement, see Advisory Circular (AC) 25-XX, Propulsion Systems Handbook. This regulation may require special consideration for certain equipment where the airplane is not capable of a return landing without exceeding equipment ratings/capabilities such as brakes and tires. Brake maximum kinetic energy rating(s) and tire maximum speed ratings may be exceeded for an immediate return/turnback, or a flapless landing, especially for large two engine airplanes.
Section 3. POWERPLANT FIRE PROTECTION
44. SECTION 25.1183 - FLAMMABLE FLUID-CARRYING COMPONENTS.
a. Rule Text.
(a) Except as provided in paragraph (b) of this section, each line, fitting, and other component carrying flammable fluid in any area subject to engine fire conditions, and each component which conveys or contains flammable fluid in a designated fire zone must be fire resistant, except that flammable fluid tanks and supports in a designated fire zone must be fireproof or be enclosed by a fireproof shield unless damage by fire to any non-fireproof part will not cause leakage or spillage of flammable fluid. Components must be shielded or located to safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart capacity on a reciprocating engine need not be fireproof nor be enclosed by a fireproof shield.
(b) Paragraph (a) of this section does not apply to-
(1) Lines, fittings, and components which are already approved as part of a type certificated engine; and
(2) Vent and drain lines, and their fittings, whose failure will not result in, or add to, a fire hazard.
(Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-11, 32 FR 6913, May 5, 1967; Amdt. 25-36, 39 FR 35461, Oct. 1, 1974; Amdt. 25-57, 49 FR 6849, Feb. 23, 1984)
NOTE: For policy and guidance on compliance with this requirement, see Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 4, section 9. Section 25.1435(c) - Hydraulic systems - Fire protection, requires compliance with § 25.1183.
NOTE: Under planned harmonization effort, paragraph 25.1183(c) of the JAR will be adopted by FAA as § 25.1183(c); the text is as follows:
"(c) All components, including ducts, within a designated fire zone must be fireproof if, when exposed to or damaged by fire, they could -
(1) Result in fire spreading to other regions of the airplane, or
(2) Cause unintentional operation of, or inability to operate, essential services or equipment."
45. SECTION 25.1185 - FLAMMABLE FLUIDS.
a. Rule Text.
(a) Except for the integral oil sumps specified in 25.1013 (a), no tank or reservoir that is a part of a system containing flammable fluids or gases may be in a designated fire zone unless the fluid contained, the design of the system, the materials used in the tank, the shut-off means, and all connections, lines, and control provide a degree of safety equal to that which would exist if the tank or reservoir were outside such a zone.
(b) There must be at least one-half inch of clear airspace between each tank or reservoir and each firewall or shroud isolating a designated fire zone.
(c) Absorbent materials close to flammable fluid system components that might leak must be covered or treated to prevent the absorption of hazardous quantities of fluids.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964 as amended by Amdt. 25-19, 33 FR15410, Oct. 17, 1968]
NOTE: For policy and guidance on compliance with this requirement, see Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 4, section 9. Section 25.1435(c) - Hydraulic systems - Fire protection, requires compliance with § 25.1185.
46. SECTION 25.1189 - SHUTOFF MEANS.
a. Rule Text.
(a) Each engine installation and each fire zone specified in § 25.1181(a) (4) and
(5) must have a means to shut off or otherwise prevent hazardous quantities of fuel, oil, deicer, and other flammable fluids, from flowing into, within, or through any designated fire zone, except that shutoff means are not required for-
(1) Lines, fittings, and components forming an integral part of an engine; and
(2) Oil systems for turbine engine installations in which all components of the system in a designated fire zone, including oil tanks, are fireproof or located in areas not subject to engine fire conditions.
(b) The closing of any fuel shutoff valve for any engine may not make fuel unavailable to the remaining engines.
(c) Operation of any shutoff may not interfere with the later emergency operation of other equipment, such as the means for feathering the propeller.
(d) Each flammable fluid shutoff means and control must be fireproof or must be located and protected so that any fire in a fire zone will not affect its operation.
(e) No hazardous quantity of flammable fluid may drain into any designated fire zone after shutoff.
(f) There must be means to guard against inadvertent operation of the shutoff means and to make it possible for the crew to reopen the shutoff means in flight after it has been closed.
(g) Each tank-to-engine shutoff valve must be located so that the operation of the valve will not be affected by powerplant or engine mount structural failure.
(h) Each shutoff valve must have a means to relieve excessive pressure accumulation unless a means for pressure relief is otherwise provided in the system.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 35FR 5677, Apr. 8, 1970; Amdt. 25-57, 49 FR 6849, Feb. 23, 1984]
NOTE: This regulation is the subject of a Federal Aviation Regulations/Joint Aivation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group is planning to recommend criteria for compliance as advisory material.
NOTE: For policy and guidance on compliance with this requirement, see Advisory Circular (AC) 25-XX, Propulsion Systems Handbook, chapter 4, section 9. Section 25.1435(c) - Hydraulic systems - Fire protection, requires compliance with § 25.1189.