(2) The results of these tests are valid only if the airplane is maintained in the condition and configuration that was tested, j.e., the integrity of the compartments, including any seals and liners, is maintained, and the ventilation systems and extinguishing systems are in their certified configuration. It is assumed for test purposes, unless a failure condition is being simulated, that a fire would not damage or destroy the integrity of the ventilation system or the compartment.
10. SMOKE DETECTION TESTS.
a. Background.
(1) Smoke or fire detection system should provide a warning before the fire-
(i) Develops into an uncontrollable or uncontainable condition, or
(ii) Damages liners, wiring, equipment, structure, essential equipment, or critical systems.
Systems which provide a warning within one minute from the start of smoke generation are considered to be in compliance with the requirements of § 25.854 for lavatories and § 25.858 for cargo compartments. If the certification basis precedes Amendment 25-54, or specifically excludes § 25.858, cargo compartment smoke detection should occur within five minutes.
(2) A smoldering fire producing a small amount of smoke in conjunction with the applicable detection time has been selected as a fire or failure condition that could be detected early enough to ensure that the fire and smoke procedures would be effective. Subjective judgment, considering the failure, size of compartment, materials contained in the compartment, and the containment methods and procedures, is needed to assess the significance of a small amount of smoke.
(3) Theatrical type smoke generators produce smoke at rates necessary for smoke penetration tests but often, if operated continuously, produce more smoke than is appropriate tor detection tests. These smoke generators are capable of simulating smoke from a vigorous fire which may be capable of destroying an airplane; a fire that should be detected long before it reaches In addition, the cool smoke produced by a theatrical smoke generator may be unacceptable for testing ceiling mounted detectors It has also been found that smoke particles, unlike the simulated smoke generated by theatrical smoke generators, will be filtered (particles stick to the inside wall of the tubes) in long smoke detector tubing runs.
Notwithstanding these factors, theatrical smoke generators are acceptable for detection tests if the smoke generator is operated for limited intervals to limit the amount of smoke generated. The lack of smoke buoyancy can be overcome by deflecting the smoke upward, and the sticking effect does not result in overly optimistic results if the compartments are small or the Par 9 13
tubing runs short. In any case, theatrical smoke in conjunction with helium may be acceptable as follows:
(i) For detection systems that do not employ long runs of smoke detector suction tubes.
(ii) In situations where the output of other types of smoke generators are either too large or too small or the smoke fouls a sensitive compartment interior. However, the cognizant ACO must approve this before the test is conducted.
b. Objective. The smoke detection test is designed to demonstrate that the smoke detection system installation will detect a smoldering fire producing a small amount of smoke.
c. Test Equipment. The smoke generating equipment used for detection teste hate is that resent the feet or the sable some a smoke may be burned in a container that is covered with a metal screen. For safety, a fire extinguisher and a metal container lid should be provided. A Beekeeper type smoke generator may be used when some restraint is placed on the quantity of smoke being generated. A pipe or cigar may be a suitable source of smoke for a closet or lavatory size compartment.
A representative material might be two or three crumpled paper towels, if paper towels are used in the lavatory. Similarly, for a crew rest area, crumpled paper towels may be burned as a smoke source if deemed acceptable by the cognizant ACO. The quantities to be burned should be established by the applicant and agreed to by the cognizant ACO. The method of generating smoke, the quantities and materials used, and the test procedures should be documented so that the test can be duplicated, if necessary, at a later date.
A helium injection modification to a theatrical smoke generator (available from the FAA Technical Center) may produce properties close to actual smoke and thus be acceptable for smoke detection tests. A helium smoke generator, however, is not acceptable for installations with long smoke detector tubing runs.
d. Test Procedure.
(1) The smoke should be generated at a location that is critical with respect to the detector's area of coverage.
(i) In cargo compartments, the smoke source should be located in areas where cargo can be loaded and secured by the airplane's onboard loading and restraint system.
(ii) In lavatories, the smoke source should be located at the most probable source, e.g., the waste (paper) receptacle.
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(iii) In crew rest areas, the most critical location of the smoke source (e.g., burn boxes) may not be the farthest location from the smoke detection system.
The cognizant ACO should be consulted in establishing the proposed location of the smoke source before conducting the crew rest area smoke detection test.
(2) The smoke generator should produce only a small amount of smoke in order to simulate a smoldering fire.
(3) For new or modified airplane cargo compartments, smoke detection should occur per the criteria stated under paragraph 10a(1).
e. Test Report. The report should provide details of the test set-up, the method, and the data. Pictures and videos may form a part of the test report.
11. SMOKE PENETRATION TESTS.
a. Background.
(1) The purpose of smoke penetration tests is to demonstrate that smoke will not enter occupied compartments of the airplane from cargo, storage or baggage compartments, equipment bays, equipment cooling systems or other non-continuously occupied areas (e.g., galleys, lavatories, or crew rest areas) containing large quantities of smoke. The definition of a large quantity" of smoke is associated with the rate of smoke generation and the volume of the compartment it must fill.
(2) Except as noted in paragraph lle(4) below, any penetration of smoke into occupied compartments from cargo, storage, or baggage compartments, equipment bays, equipment cooling systems, or other non-continuously occupied areas (e.g., galleys, lavatories, or crew rest areas) during the tests is unacceptable because the toxicity of the smoke is unpredictable and the smoke exposure might continue or increase to a hazardous level before a landing can be made. The smoke concentrations and exposure time in an actual fire or smoke situation might be well beyond those demonstrated during the limited duration of the smoke penetration tests. Generally, any smoke penetration during the tests demonstrates that the smoke containment means or control methods are unacceptable.
b. Objective. The objective of this test is to demonstrate that a large quantity of smoke generated in cargo, storage, or baggage compartments and other non-continuously occupied areas (e.g., galleys, lavatories, or crew rest areas) will not penetrate into any occupied compartment. This test also demonstrates that a large quantity of smoke generated in equipment bays or equipment cooling systems will not penetrate into the passenger compartment, and if any smoke penetrates into the cockpit, it can be readily removed using the AFM emergency fire and smoke procedures.
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c. Limitations. Successful completion of the smoke penetration tests does not relieve the requirement to conduct carbon dioxide, carbon monoxide, and extinguisher tests in complying with §§ 25.831(b) and (c), 25.851 and 25.855.
d. Equipment.
(1) A smoke generator that has the capability to fill the compartment being tested with smoke and keep it filled for the duration of the test should be selected. To save flight test time, it should be verified on the ground that the generator can continuously produce sufficient quantities of smoke to produce a dense concentration in the compartment being tested. The criteria of paragraph lle(2) should be met with the airplane pressurization and ventilation systems operated to approximate the airflow for the test condition being simulated.
(2) Generally, the theatrical type generators produce smoke at an adequate rate for smoke penetration tests. Certain models of this type generator may not be adequate for some of the larger cargo compartments and it may be necessary to move the generator around the compartment or use multiple generators.
(3) The smoke generator should not produce smoke that is noxious, corrosive, or toxic, and should be capable of immediate shutdown if a hazardous condition develops. Portable protective breathing equipment, with spare breathing gas bottles, should be provided for test personnel.
e. Test Procedure.
The smoke generator(s) should be placed to generate smoke in the Class B, C, D, or t cargo, storage, or baggage compartment, the equipment Day, equipment cooling system, or non-continuously occupied area (e.g., galley, lavatory, or crew rest area in the position most likely to result in penetration of smoke into occupied areas of the airplane. All lights in occupied compartments and baggage compartments should be on. For some larger compartments, such as a freighter main deck, it may be necessary to use multiple smoke generators to maintain the required smoke density.
Smoke should be generated continuously until the compartment or area is completely filled with smoke. The compartment or test area is considered filled with smoke when an FAA observer, anywhere in the compartment, cannot see his/her hand when it is held approximately 18 inches in front of his/her face unless the hand is silhouetted by a window or interior light. If applicable, the AFM fire and smoke emergency procedures should be initiated no less than 30 seconds after detection.
(3) After the compartment or area is completely filled with smoke, generation should be continued as necessary to maintain the compartment smoke density attained when the compartment is pronounced "full" for an additional fifteen minutes. The fifteen minute test duration can be reduced if it is apparent that a "steady state" condition relative to smoke penetration has been reached and continuing the test will not produce smoke penetration into occupied areas.
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The chart at the end of this section summarizes the smoke penetration test procedures described in paragraphs 1le(2) and (3).
(4) The FAA observer in the occupied compartment should verify that smoke does not penetrate occupied compartments (An alternative technique for this determination is discussed under item (7) below). The formation of a light haze indicates that the ventilation requirements of § 25.831(b) are not being met. Except as noted below, smoke should not penetrate occupied compartments.
(i) Wisps of smoke that enter and immediately exit at the occupied compartment boundaries are acceptable as long as a light haze or stratified haze does not form. If this condition (i.e., wisps of smoke at the compartment boundary) occurs, the 15-minute test procedure of paragraph lle(3) should be followed.
(ii) A crewmember must be able to extinguish fires in Class B cargo, storage, or baggage compartments or other non-continuously occupied areas (e.g., galley, lavatory, or crew rest area). This means that the crewmember must pass through the compartment's smoke barrier or access door at least once. The crewmember entering or exiting the compartment may disturb the normal airflow and cause some smoke to enter the passenger or flightcrew compartment. This is acceptable if the smoke that enters the passenger or flightcrew compartment is dissipated rapidly.
(iii) Equipment bays and open or closed loop equipment cooling systems may interface with the cockpit systems. When penetration tests are conducted in the equipment bay or in the equipment cooling system, a small amount of smoke may penetrate the cockpit. That smoke should dissipate rapidly when the AFM smoke and fire procedures are used.
(5) If the smoke generator(s) do not completely fill and keep the cargo, storage, or baggage compartment, equipment bay, equipment cooling system or other non-continuously occupied area (e.g., galley, lavatory, or crew rest area filled with smoke, additional tests should be conducted with the generator (s) relocated as necessary.
(6) Section 25.855(i) requires that smoke should not be detected in and extinguisher tests are completed successfully. The same criteria apply when smoke detectors or extinguishing systems are installed in equipment bays or equipment cooling systems to comply with § 25.831 (c) or § 25.1309(c).
An Alternative Technique to determine smoke penetration under Step
(4) Above: (Exceptions (i), (ii), and (iii) still apply). In lieu of the lighter missibility meas wing de sets used ethelight transmissibility should be measured through smoke along a three foot light path using a calibrated photoelectric cell and a laser that produces light with a wavelength of 632.8 nanometers. The light path may be folded provided each path through the smoke is no less than 18 inches. The calibration of the Par 11 17
light transmissibility measuring device should be checked by using "Wratten" filters as outlined in National Bureau of Standards Information Report (NBSIR) /, dated June 19//, (reterence paragrapn 1lb of the NBSIR) or any other acceptable calibration procedure.
(1) Light transmissibility reading should be taken in the occupied area at seated head height level (4 feet above the floor) and at least 18 inches from the partition between the occupied compartment and the compartment in which the smoke is being generated.
(ii) If visible smoke is present in the occupied compartment, the reading should be taken at a number of points between the armrest and standing head height level (6 feet above the floor), and at least 18 inches away from the partition between the occupied compartment and the compartment in which the smoke is being generated.
(iii) The transmissibility level in any occupied compartment should not be less at any time during the test than it was before the start of the smoke tests, i.e., zero plus any prevailing atmospheric reduction in transmissibility.
Smoke Penetration Test Procedure TIME = 0 t+30 seconds • Additional 15 minutes • ≥ * Smoke * Initiate AFM Compartment filled detection. fire and smoke with smoke?
emergency [see paragraph 11e(2)] procedures.
YES → End Test.
NO < Continuously generate smoke. Maintain smoke density.
(Generate smoke as necessary) < Continuously check for smoke penetration into occupied compartments.
* If compartment is equipped with a smoke detection system.
NOTE: This test procedure is not intended to show compliance with the requirements of § 25.857, § 25.858, and § 25.1301 as they relate to smoke detection.
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1/6/94 AC 25-9A
12. SMOKE EVACUATION TESTS.
a. Background.
(1) Cockpit smoke evacuation tests verify that smoke, from sources within or contiguous with the cockpit, can be readily evacuated as required by § 25.831(d). Typical commercial large transport airplanes are capable of evacuating dense cockpit smoke within approximately 90 seconds after the AFM fire and smoke emergency procedures are initiated. Three minutes is an acceptable maximum time to evacuate smoke from any transport category airplane cockpit. In the case of a cargo conversion supplemental type certificate, the cognizant ACO may accept the original cockpit smoke evacuation test provided it is substantiated by compartment airflow analysis.
The cockpit smoke evacuation test procedure is intended to measure the capability of the smoke clearance procedures against a standard condition,
i.e., to clear the cockpit of smoke after the pilot's view is obscured, without any further smoke being generated.
Although the FAR does not require it, it is recommended that the capability to evacuate continuously generated smoke from the cockpit be demonstrated. Equipment and means designed beyond what is prescribed in the regulations may only be used if those means are readily usable and enable the pilot to see all the instruments, switches, working panels/lights, and mechanisms necessary to safely land the airplane in all weather conditions.
(2) Smoke evacuation tests are not required for passenger compartments.
(3) When the ventilation of lavatories, galleys, or crew rest areas is not isolated from that of the passenger compartment, smoke evacuation tests are not required.
b. Objective. The objective of the in-flight smoke evacuation test is to demonstrate that the AFM emergency fire and smoke procedures provide means to clear the cockpit of dense smoke at an acceptable rate. This test should also demonstrate that the flightcrew can use the procedures without introducing any additional hazard.
evacuation tests (se paragraph late penetration tests may
d. Limitations.
(1) Some airplane designs have automatic cockpit or instrument light dimming features to reduce light intensity for night flight. Smoke may cause the automatic dimming feature to function, thus making instrument visibility more difficult. A manual means to override the dimming control should be provided for each dimming circuit. There should be a procedure that specifies that the light or instrument intensity be turned up, as necessary, when smoke is present in the cockpit.
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(2) If it is determined that specific systems, e.g., autopilot, yaw damper, etc., are to be used as part of the smoke evacuation procedure, then their use should be incorporated into the AFM emergency procedures and the systems should be operational for dispatch.
e. Test Procedures. The smoke evacuation tests should be conducted with smoke generated in the cockpit as follows:
(1) The cockpit door or curtain, if installed, should be closed for the test. The crew should don protective breathing equipment as soon as the smoke is evident.
(2) When the cockpit instruments are obscured (dial/panel indicator numbers or letters become indiscernible), smoke generation should be terminated, and the appropriate AFM and operations manual (if applicable) fire and smoke procedures should be initiated. The smoke should be reduced within three minutes such that any residual smoke (haze) does not distract the flightcrew or interfere with flight operations.
(3) Although not mandatory, if the applicant wishes to demonstrate protection from smoke generated by a continuous source in the cockpit, smoke should be generated continuously. The crew should don protective breathing equipment and initiate smoke evacuation procedures as soon as smoke becomes evident and, activate any optional vision enhancement devices, if approved.
Konate 1. wes талг RONALD T. WOJNAR Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100 20 Par 12
Appendix 1
APPENDIX I This appendix addresses those rules that may be complied with by the use of smoke detection tests, smoke penetration tests and smoke evacuation tests.
This appendix discusses the rules as they relate to the specific test.
Certain rules that are complied with by measuring gas concentrations are discussed in a cursory manner, as well, to show that these rules are not to be confused with rules requiring compliance by smoke detection, smoke penetration and smoke evacuation tests.
Section 25.831 has been applied, in the general sense, in consideration of normal operating conditions and failures that could expose the passengers to harmful or hazardous concentrations of gases or vapors. Fuel fumes are to be included in the evaluation [ref. 4b.371]. Smoke, caused by failure, is part of this consideration. Hazardous concentrations of mixed gases and vapors from combustion (smoke) have not been defined. See the discussion under compliance with § 25.857(b).
Section 25.831(b) (1), originally in § 4b.371, addresses exposure to carbon monoxide. Section 4b.371 also addressed fuel fumes and made reference to § 4b.467 [Exhaust system and installation components]. Section 25.831(b) (1) was written to cover carbon monoxide exposure from fuel systems, powerplants and combustion heaters during normal operation and failure conditions.
Currently, this rule also applies to ventilation air from turbojet or APU bleed air systems. Methods of compliance with § 25.831(b)(1) are not the subject of this AC.
Section 25.831(b)(2), originally in § 4b.371, addresses exposure to carbon dioxide. The original intent was to address temporary exposure to carbon dioxide extinguishing agent and to define an exposure level when protective breathing equipment should be used. Currently, this specific portion of the rule is under review. Methods of compliance with § 25.831(b)(2) are not the subject of this AC.
Section 25.831 (d) addressed the accumulation of hazardous quantities of smoke in the cockpit area. Hazardous quantities of smoke have not been defined.
Common certification practice has been to assume that limited electrical fires [possibly other fire sources] within the cockpit or connecting electronic bays may generate enough smoke to be considered hazardous. The cockpit smoke evacuation procedures, addressed in this AC, have been devised as a method to comply with § 25.831(d).
Section 25.851 addresses exposure to extinguishing agents from both portable and built-in extinguishers. This rule can be applied generally where coverage is not provided in other specific rules, for example, § 25.1197, under 'Power Plant Fire Protection" and § 25.857, "Cargo Compartment Classification."
Verifying exposure concentrations of extinguishing agent applied within an occupied compartment is not the subject of this AC.
Section 25.855(h) establishes the use of flight test when showing compliance with § 25.857 (cargo compartment accessibility, penetration of hazardous
Appendix 1 quantities of smoke into occupied areas, and dissipation of extinguishing agent in Class C compartments).
Compliance with § 25.857(b)(2), (c)(3), (d) (2) and (e) (4) is one subject of this AC, le., showing there are means of excluding hazardous quantities of smoke, flames, or extinguishing agent, from any compartment occupied by the crew or passengers.
One method of showing there are means of excluding hazardous quantities of smoke and extinguishing agent would be to define all the probable combustion sources within the cargo compartment and combinations of combustion byproducts combined with and without the extinguishing agent, and show that the possible exposure concentrations of these byproducts and extinguishing agents will not exceed human tolerances. In addition to the complication of trying to define the concentrations of all the probable combinations of combustion byproducts and extinguishing agent, the complication exists that the acceptable human tolerance to various combinations of combustion byproducts and extinguishing agent have not been defined. For these reasons, this approach to compliance with § 25.857(b)(2), (c)(3), (d) (2) and (e) (4) has not been attempted.
As a practical method of showing there are means of excluding hazardous quantities of smoke, flame or extinguishing agent, from any compartment occupied by the crew or passengers, the FAA has accepted the use of flame barriers and demonstrations showing the prevention of smoke penetration into occupied areas, i.e., smoke penetration tests.
A small amount of smoke is allowed into the passenger compartment, if a crewmember has to enter into the Class B cargo compartment from the passenger compartment. See the discussion in the Cargo Compartment smoke penetration tests, see lle. (4).
Section 25.1301 requires that installed equipment function properly when installed. Smoke detection tests and smoke evacuation tests have been used to show that the detection and ventilation systems of galleys, lavatories, and crew rest areas function properly.
Section 25.1309 requires consideration of failures and the effects on occupants. See AC 25.1309-1A. Section 25.1309 is a rule of general applicability which may be applied where specific rules do not apply.
1/6/94 AC 25-9A Appendix 2
APPENDIX II
PAPER TOWEL BURN BOX SMOKE GENERATOR The smoke detection testing conducted for crew rest and lavatory areas employing ionization type detection systems uses a smoke generator named the "Burn Box" which is described in the attached figures 1 through 4. The Burn Box consists of an aluminum outer containment box, approximately 9.5" square (figure 1), surrounded/supporting an aluminum inner burn chamber 6.5" x 5.6" X
8.0" (figures 2 and 3). The top (hinged) surface of the inner chamber is a fine mesh steel in order to help contain the ashes of the burning fuel.
Quarter sheets of standard 10" X 13.5" lavatory paper towel are folded accordion style (figure 4) and alternately stacked into the inner burn chamber. A match hole is provided on the side of the inner box, with access to this hole by way of a hinged side of the outer containment box. Once the fuel charge is ignited, the hinged side of the containment is closed and the hinged top lid of the outer containment box is opened to allow the smoke to begin escaping from the generator. The time to detection begins at this point.
DESCRIPTION OF OPERATIONS Rest of snote from these test? CAUTION: Provide temporary fire resistant protective coverings for any decorative surfaces or flammable materials which could be affected by
(1) Place Burn Box generator(s) at the critical location within the compartment to be tested.
(2) Open top door of the box.
(3) Open top door/screen of the inner box.
(4) Place desired number of folded 1/4 sheets of paper towels (CROWN C-FOLD 241 towels folded accordion style) uniformly on the screen inside the inner box.
(5) Close top door/screen of the inner box.
(6) Close top door of the outer box.
(7) Open side door (s) of outer boxes).
(8) Ignite paper towels inside generator by extended lit match through 3/4 inch diameter hole through front side of inner box (accessible through open side door of outer box). After paper towel (s) are lit, close side door.
(9) After all generators are lit, simultaneously open top door(s) of outer box (es) to release smoke.
(10) Begin time to detection when all boxes) are opened fully.
Appendix 2
SELECTING NUMBER OF BOXES TO USE
(1) Crew rest areas utilizing ambient lonization-type smoke detection systems:
(a) For volumes up to 500 cubic feet use 2 burn boxes with a total of 3 paper towels (see description of operation step 4) 6 quarter sheets folded accordion style in each box. Light either simultaneously or sequenced up to 15 seconds apart.
(b) For volumes greater than 500 cubic feet: scale up fuel (paper towels) by adding 1.5 paper towels for each additional 150 cubic feet. Add Burn Boxes as required, to maintain control of the flame exiting the top of the Burn Box during testing.
(c) Crew rest areas enclosed with curtains, using Ionization type detectors.
(i) If designed with one detector in each bunk, use one burn box with one full sheet of paper towel.
(ii) If crew rest is designed to have one detector protect more than one bunk, use method described in (1) (a) or (b) above, depending on the volume enclosed.
(2) Standard Lavatory with ambient Ionization type detectors:
One Burn Box with 1 sheet of paper towel as fuel placed near the waste receptacle.