Minimum Performance Standard for 

Aircraft Cargo Compartment Halon 

Replacement Fire Suppression 

Systems (2nd Update) 

John W. Reinhardt 

June 2005 

DOT/FAA/AR-TN05/20 

This document is available to the public through the National Technical 

Information Service (NTIS), Springfield, Virginia 22161. 

U.S. Department of Transportation 

Federal Aviation Administration

ote technical note technic

a
NOTICE 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information exchange. The 

United States Government assumes no liability for the contents or use 

thereof. The United States Government does not endorse products or 

manufacturers. Trade or manufacturer's names appear herein solely 

because they are considered essential to the objective of this report. This 

document does not constitute FAA certification policy. Consult your local 

FAA aircraft certification office as to its use. 

This report is available at the Federal Aviation Administration William J. 

Hughes Technical Center’s Full-Text Technical Reports page: 

actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). 
Technical Report Documentation Page 

1. Report No.

DOT/FAA/AR-TN05/20 

2. Government Accession No. 3. Recipient's Catalog No.

4. Title and Subtitle 5. Report Date

MINIMUM PERFORMANCE STANDARD FOR AIRCRAFT CARGO June 2005

COMPARTMENT HALON REPLACEMENT FIRE SUPPRESSION SYSTEMS 6. Performing Organization Code

(2nd UPDATE) AAR-440 

7. Author(s)

John W. Reinhardt 

8. Performing Organization Report No.

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)

Federal Aviation Administration 

William J. Hughes Technical Center 

Airport and Aircraft Safety 

Research and Development Division 11. Contract or Grant No.

Fire Safety Branch 

Atlantic City International Airport, NJ 08405 

12. Sponsoring Agency Name and Address

U.S. Department of Transportation 

Federal Aviation Administration

13. Type of Report and Period Covered

Technical Note 

Office of Aviation Research 

Washington, DC 20591 

14. Sponsoring Agency Code

ANM-112 

15. Supplementary Notes

16. Abstract

This technical note presents the second update to the minimum performance standards that a Halon 1301 replacement or alternate 

system for aircraft cargo compartment must meet as part of the aircraft certification procedures. This document replaces report 

number DOT/FAA/AR-TN03/6. This standard considers gaseous and nongaseous fire suppression systems for full-scale fire 

testing. This report update includes the corrections made to the aerosol can simulator specifications, acceptance criteria section, 

and the new criteria for the aerosol can explosion test. In addition, some sections were added to the test requirements to clarify 

some testing procedures. 

17. Key Words 18. Distribution Statement

Aircraft cargo compartment, Full-scale fire testing, Combustible 

fires, Bulk-load fires, Containerized fires, Surface burning, 

Flammable liquid fires, Aerosol explosion, Halon 1301 

Replacement/alternative, Minimum performance standard, 

Gaseous and nongaseous fire suppression systems 

This document is available to the public through the National 

Technical Information Service (NTIS), Springfield, Virginia 

22161. 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price

Form DOT F1700.7 (8-72) Reproduction of completed page authorized 

Unclassified Unclassified 30 
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY vii 

1. INTRODUCTION 1 

2. SCOPE 2 

3. AGENT SELECTION GUIDANCE 3 

3.1 Environmental 3 

3.2 Toxicology 3 

4. TEST REQUIREMENTS 3 

4.1 Test Cell (Cargo Compartment) 3 

4.2 Instrumentation 4 

4.3 Fire Scenarios 4 

4.3.1 Bulk-Load Fire 4 

4.3.2 Containerized-Load Fire 5 

4.3.3 Surface-Burning Fire 5 

4.3.4 Aerosol Can Explosion Simulation 5 

4.3.5 Aerosol Can Explosion Simulation (Short Version) 8 

4.4 Ignition Source 8 

4.4.1 Resistance Heat 8 

4.4.2 Electrical Arc 8 

4.5 Suppression System Design 9 

4.6 Suppression System Activation 10 

4.7 Test Duration 10 

5. ACCEPTANCE CRITERIA 10 

6. REFERENCES 12 

APPENDICES 

A—Determination of Acceptance Criteria Values 

B—Aerosol Can Explosion Simulator Drawings 

iii
LIST OF FIGURES 

Figure Page 

1 Cargo Compartment Layout and Instrumentation Locations 13 

2 Bulk-Load Fire Test Setup 13 

3 Igniter Box 14 

4 Containerized-Load Fire Test Setup 14 

5 LD-3 Container 15 

6 LD-3 Container Arrangement 15 

7 Surface-Burning Fire Pan 16 

8 Schematic of Aerosol Can Explosion Simulator 16 

9 Aerosol Can Explosion Simulation Test Setup 17 

10 Aerosol Can Explosion Simulation Test Setup (Short Version) 17 

11 Acceptance Criteria Boundaries 18 

LIST OF TABLES 

Table Page 

1 Acceptance Criteria 18 

iv
LIST OF ACRONYMS 

AD Airworthiness Directive 

CFR Code of Federal Regulations 

DC Direct current 

FAA Federal Aviation Administration 

GWP Global Warming Potential 

JAA Joint Aviation Authority 

JAR Joint Airworthiness Requirements 

MPS Minimum performance standard 

ODP Ozone depletion potential 

v/vi
EXECUTIVE SUMMARY

This technical note establishes the minimum performance standard (MPS) that a Halon 1301 

replacement aircraft cargo compartment fire suppression system must meet. This MPS was 

developed in conjunction with the International Aircraft Fire Protection Systems Working 

Group, formerly known as the International Halon Replacement Working Group. It describes 

the tests that shall be performed to demonstrate that the performance of the replacement agent 

and system provides the same level of safety as the currently used Halon 1301 system. The 

results of these tests will be used to determine the required concentration levels to adequately 

protect an aircraft cargo compartment against fire and hydrocarbon explosions. The 

Supplemental Type Certificate applicant shall provide the minimum agent protection 

concentration, density, etc., to the Federal Aviation Administration (FAA) Aircraft Certification 

Office with an objective way of measuring it. Currently, the FAA Transport Airplane 

Directorate, in conjunction with the Joint Aviation Authority, is developing an advisory circular 

to address the certification of an aircraft cargo compartment fire extinguishing or suppression 

system. This MPS update replaces the standard reported in FAA Technical Note DOT/FAA/ARTN03/6, “Minimum Performance Standard for Aircraft Compartment Halon Replacement Fire 

Suppression Systems.” 

The four different MPS fire test scenarios that new cargo compartment fire suppression systems 

must meet are bulk-load fire, containerized-load fire, flammable liquid fire (surface burning), 

and an aerosol can explosion simulation. The bulk- and containerized-load fires, which are deepseated fire scenarios, use shredded paper loosely packed in cardboard boxes to simulate the 

combustible fire load. The difference between these two tests is that in the bulk-load fire 

scenario the boxes are loaded directly into the cargo compartment, while in the containerizedload fire scenario, the boxes are stacked inside an LD-3 container. The surface-burning test 

(Class B fire) uses 0.5 U.S gallon (1.89 liters) of Jet A as fuel. The aerosol can explosion 

simulation tests are executed by using an aerosol can simulator containing a flammable and 

explosive mixture of propane, alcohol, and water. This mixture ignites or explodes when it is 

exposed to an arc from sparking electrodes. At least five tests per MPS scenario must be 

conducted. These tests shall be performed in a 2000-ft3

 simulated aircraft cargo compartment. 

The suppression performance of a new agent, once the data is collected and analyzed, is then 

compared with the standard acceptance criteria to determine if it passes or fails the fire tests. 

None of the peak temperatures and areas under the time-temperature curves may exceed the 

values specified in the acceptance criteria table. The acceptance criteria are as follows: 

• For the bulk-load fire scenario, the average of the five test peak temperatures shall not 

exceed 720°F (382°C), starting 2 minutes after the suppression system is initially 

activated until the end of the test. In addition, the average of the five test peak areas 

under the time-temperature curve shall not exceed 9940°F-min (5504°C-min). The area 

should be computed from 2 minutes (t3) after the time of initial suppression system 

activation (t2) to 28 minutes after t3.

• For the containerized-load fire scenario, the average of the five test peak temperatures 

shall not exceed 650°F (343°C), starting 2 minutes after the suppression system is 

initially activated until the end of the test. The average of the five test peak areas under 

vii
the time-temperature curve shall not exceed 14,040°F-min (7,782°C-min). The area 

should be computed from 2 minutes (t3) after the time of initial suppression system 

activation (t2) to 28 minutes after t3.

• For the surface-burning fire scenario, the average of the five test peak temperatures shall 

not exceed 570°F (299°C), starting 2 minutes (t3) after the suppression system is initially 

activated until the end of the test, 3 minutes after t3. In addition, the average of the five 

tests peak areas under the time-temperature curve shall not exceed 1230°F-min 

(665°C-min) for the same period mentioned in the previous sentence.

• For the aerosol can explosion simulation scenario, no evidence of an explosion shall be 

present in the compartment at the time the simulator is activated, such as no overpressure 

(0.0 psig) or deflagrations. In addition, when the agent concentration is below its inert 

concentration, the explosion intensity and peak pressures shall not be greater than the 

values exhibited during an explosive event when no suppression agent is present in the 

compartment. 

Appendix A presents a table showing how the acceptance criteria values were determined based 

on the Halon 1301 test data. Appendix B contains the aerosol can explosion simulator drawings. 

viii
1. INTRODUCTION. 

The Code of Federal Aviation Regulations (CFR) and Joint Airworthiness Requirements (JAR) 

require fire suppression systems for some classifications of cargo compartments. In the past, the 

aircraft industry selected Halon 1301 total flood fire suppression systems as the most effective 

means for complying with the regulations. Because of the ban on production of Halon 1301 

(effective January 1994, as mandated by the Montreal Protocol), new fire suppression systems 

will need to be certified when Halon 1301 is no longer available. The tests described in this 

standard are one part of the total Federal Aviation Administration (FAA) and the Joint Aviation 

Authority (JAA) certification process for cargo compartment fire suppression systems. 

Compliance with other applicable regulations, some of which are listed below, is also required. 

Applicants attempting to certify replacement systems are encouraged to discuss the required 

process with regulatory agencies prior to conducting tests. Currently, the FAA Transport 

Airplane Directorate, in conjunction with the JAA, is developing an advisory circular to address 

the certification of aircraft cargo compartment fire extinguishing or suppression system 

employing halon replacement agents. 

The following existing CFRs/JARs pertain to cargo compartment fire suppression systems: 

14 CFR 25.851 [Doc. No.5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-54, 45 FR 

60173, Sep. 11, 1980; Amdt. 25-72, 55 FR 29783, Jut. 20, 1990; Amdt. 25-74, 56 FR 15456, 

Apr. 16, 1991] “(b) Built-in fire extinguishers. If a built-in fire extinguisher is provided- 

(1) Each built-in fire extinguishing system must be installed so that- 

(i) No extinguishing agent is likely to enter personnel compartments will be hazardous to the 

occupants; and 

(ii) No discharge of the extinguisher can cause structural damage. 

(2) The capacity of each required built-in fire extinguishing system must be adequate for any fire 

likely to occur in the compartment where used, considering the volume of the compartment and 

the ventilation rate.” 

14 CFR 25.855 [Doc. No.5066, 29 FR 18291. Dec. 24, 1964, as amended by Amdt. 25-15, 32FR 

13266, Sep. 20, 1967; Amdt. 25-32, 37 FR 3972, Feb. 24, 1972; Amdt. 25-60, 51 FR 18242, 

May 16, 1986; Amdt. 25-72, 55 FR 29784, Jut. 20, 1990; Amdt. 25-93, 63 FR 8048, Feb. 17, 

1998] “(h) Flight tests must be conducted to show compliance with the provisions of Sec. 25.857 

concerning- 

(1) Compartment accessibility, 

(2) The entries of hazardous quantities of smoke or extinguishing agent into compartments 

occupied by the crew or passengers, and 

(3) The dissipation of the extinguishing agent in Class C compartments. 

(i) During the above tests, it must be shown that no inadvertent operation of smoke or fire 

1
detectors in any compartment would occur as a result of fire contained in any other compartment, 

either during or after extinguishment, unless the extinguishing system floods each such 

compartment simultaneously.” 

14 CFR 25.857 [Doc. No.5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-32, 37FR 

3972, Feb. 24, 1972; Amdt. 25-60, 51 FR 18243, May 16, 1986; Amdt. 25-93, 63 FR 8048, Feb. 

17, 1998] “(c) Class C. A Class C cargo compartment is one not meeting the requirements for 

either a Class A or Class B compartment but in which- 

(1) There is a separate approved smoke detector or fire detector system to give warning at the 

pilot or flight engineer station. 

(2) There is an approved built-in fire extinguishing or suppression system controllable from 

the cockpit; 

(3) There are means to exclude hazardous quantities of smoke, flames, or extinguishing 

agent, from any compartment occupied by the crew or passengers; 

(4) There are means to control ventilation and drafts within the compartment so that the 

extinguishing agent used can control any fire that may start within the compartment.” 

In addition to these regulations, the FAA issued Airworthiness Directive (AD) 93-07-15 that 

required, among other things, that after November 2, 1996, the Class B cargo compartments on 

Boeing Models 707, 727, 737, 747, and 757 and McDonnell Douglas Models DC-8, DC-9, and 

DC-10 series airplanes have improved fire protection features. One of three options available to 

comply with this AD is to modify Class B cargo compartments on these airplanes to comply with 

the requirements for Class C compartments. This option would require the installation of a fire 

suppression system. 

One other area of rulemaking activity relating to cargo compartment suppression system 

requirements is the “Revised Standards for Cargo or Baggage Compartments in Transport 

Category Airplanes, Final Rule,” amendments 25-07 and amendments 121-269, effective March 

19, 1998. This rule eliminates Class D cargo compartments on newly certified aircraft under 14 

CFR Part 25 and requires existing Class D compartments on 14 CFR Part 121 certified passenger 

aircraft to comply with the detection and suppression/extinguishing system aspects of Class C 

cargo compartment requirements by March 19, 2001. This rule was issued by the FAA and at 

this time applies only to aircraft operated by U.S.-based airlines. 

2. SCOPE. 

This document establishes the minimum performance standard (MPS) that a cargo compartment 

halon replacement fire suppression system must meet. It describes the tests that shall be 

performed to demonstrate that the performance of the replacement agent and systems equals the 

performance of the currently approved Halon 1301 systems. 

2
3. AGENT SELECTION GUIDANCE. 

3.1 ENVIRONMENTAL.

The replacement agent must be approved under the U.S. Environmental Protection Agency, 

Clean Air Act, Significant New Alternatives Policy program, or other international governmental 

approving programs. The primary environmental characteristics to be considered in assessing a 

new agent are Ozone Depletion Potential (ODP), Global Warming Potential (GWP), and 

Atmospheric Lifetime. The agent selected should have environmental characteristics in harmony 

with international laws and agreements, as well as applicable local laws. This MPS sets out the 

means of assessing the technical performance of potential alternatives. In selecting a new agent, 

it should be noted that an agent that does not have a zero or near-zero ODP and the lowest 

practical GWP and Atmospheric Lifetime may have problems in terms of international 

availability and commercial longevity. 

3.2 TOXICOLOGY. 

The toxicological acceptability of an agent is dependent on how it is used. As a general rule, the 

agent must not pose an unacceptable health hazard for workers during installation and 

maintenance of the suppression system. At no time should the concentration cause an 

unacceptable health hazard in areas where passengers or workers are present or where leakage 

could cause an agent to enter an occupied area. Following the release of the agent during fire 

suppression, the cumulative effect of the agent, its pyrolytic breakdown products, and the byproducts of combustion must not pose an unacceptable health hazard. 

14 CFR 25.851, 25.855, and 25.857 all address the issue of hazardous quantities of smoke, gas, 

or extinguishing agent in occupied compartments. The fire tests described in this MPS do not 

address these issues. 

4. TEST REQUIREMENTS.

4.1 TEST CELL (CARGO COMPARTMENT). 

The fire tests are conducted inside a simulated, below-floor cargo compartment of a wide-body 

aircraft. The volume of the compartment is 2000 ±100 cubic feet (56.6 ±2.8 m3

), see figure 1. 

The leakage rate from the compartment is 50 ±5 cubic feet per minute (1.4 ±0.14 cubic meter per 

minute). The leakage from the compartment is configured to simulate the U shape of the cargo 

door seals that are on an actual aircraft. This can be done by installing perforated ducts inside 

the compartment in the shape of the perimeter of a cargo door and then venting those ducts 

outside the test article. A variable speed fan installed in the exit of the duct draws air out of the 

compartment. One-inch-diameter holes spaced at 5-inch (12.7-cm) intervals in a round, 4-inchdiameter steel duct has been shown to be effective. The perforated ducts are installed on the side 

of the cargo compartment opposite the ignition box for the bulk- and containerized-load fire 

scenarios. The return air that goes back into the compartment should be evenly distributed and 

not from anyone location. 

3
4.2 INSTRUMENTATION.

Temperature measurements are taken throughout the cargo compartment. Type K 

chromel/alumel 22-gauge thermocouples have been found to be effective at measuring 

temperatures in the range these fire scenarios produce. Ceiling thermocouples are evenly spaced 

along the compartment ceiling at 5-foot intervals. One of the ceiling thermocouples is installed 

directly above the initial ignition location for all fire scenarios. The beads of the ceiling 

thermocouples are 1 inch (2.5 cm) below the compartment ceiling. At least one thermocouple is 

placed on the compartment sidewall 1 foot below ceiling level and centered on the fire ignition 

location. The sidewall thermocouple is installed on the compartment wall nearest the ignition 

location. At least two additional thermocouples are placed in and above the box containing the 

igniter for the bulk- and containerized-load fire scenarios. The purpose of these two 

thermocouples is to monitor and verify the ignition of the boxes. The readings are not part of the 

acceptance criteria. Care should be taken to prevent these thermocouples from contacting the 

energized coil of the nichrome wire. 

A continuous gas analyzer with a real-time display of the gas (extinguishing agent) volumetric 

concentration is required for the aerosol can explosion simulation fire scenario when the 

suppression system is a gaseous total flood system (short-test version). A continuous gas 

analyzer may also be required, depending on the suppression system design, for the bulk- and 

containerized-load fire scenarios. The accuracy of the analyzer shall be ±5% of the reading. The 

gas analyzer is used to measure the concentration of the gaseous suppression agent. The datasampling rate for all the temperature measurements and the gas concentrations should be at least 

one data point every 5 seconds. 

A pressure transducer is also required for the aerosol can explosion simulation fire scenario. The 

maximum transducer pressure range is 0-50 psig. The minimum frequency response of the 

transducer is 3000 Hz. Omega® manufactures several transducers suitable for this application. 

The transducer is mounted on the ceiling in the geometric center of the compartment. The datasampling rate for the pressure transducer is at least 3000 data points per second. 

4.3 FIRE SCENARIOS. 

The aircraft cargo compartment fire suppression system must successfully control the following 

four fire scenarios. Five replicate tests are required for each fire test scenario. 

4.3.1 Bulk-Load Fire. 

The fire load for this scenario consists of single-wall corrugated cardboard boxes, with nominal 

dimensions of 18 by 18 by 18 inches (45.7 by 45.7 by 45.7 cm). The weight per unit area of the 

cardboard is 0.11 lbs/ft2

 (0.5417 kg/m2). The boxes are filled with 2.5 pounds (1.1 kg) of loosely 

packed standard weight office paper shredded into strips (not confetti) weighing 4.5 ±0.4 pounds 

(2.0 ±0.2 kg). The boxes are conditioned to room standard conditions. The flaps of the boxes 

are tucked under each other without using staples or tape. The boxes are stacked in two layers in 

the cargo compartment in a quantity representing 30% of the cargo compartment empty volume. 

For a 2000-cubic-foot (56.6-m3) compartment, this requires 178 boxes. The boxes touch each 

other to prevent any significant air gaps between boxes. The fire inside the ignition box is 

4
started by applying 115 Vac to a 7-foot (2.1-m) length of nichrome wire. The wire is wrapped 

around four folded (in half) paper towels. The resistance of the nichrome igniter coil is 

approximately 7 ohms. The igniter is placed into the center of a box on the bottom outside row 

of the stacked boxes. Several ventilation holes are placed in the side of the box to ensure that the 

fire does not self-extinguish. Ten 1.0-inch (2.5-cm) -diameter holes have been shown to be 

effective (see figures 2 and 3). 

4.3.2 Containerized-Load Fire. 

The same type of paper-filled cardboard boxes and the same type of igniter used in the bulk-load 

fire scenario is used in this scenario. The boxes are stacked inside an LD-3 container as shown 

in figure 4. The boxes touch each other to prevent any significant air gaps between them. The 

container is constructed of an aluminum top and inboard side, a Lexan (polycarbonate) front, and 

the remainder of steel. Two rectangular slots for ventilation are cut into the container in the 

center of the Lexan front and in the center of the sloping sidewall. The slots are 12 by 

3 ±1/4 inches (30.5 by 7.6 ±0.6 cm) (see figure 5). The igniter is placed in a box on the bottom 

row, in the center column next to the sloping side of the container. Ventilation holes are placed 

on the front face of the box facing the ventilation hole. Ten 1.0-inch (2.5-cm) -diameter holes 

have been shown to be effective. Two additional empty LD-3 containers are placed adjacent to 

the first container (see figure 6). 

4.3.3 Surface-Burning Fire. 

One-half U.S. gallon (1.9 liters) of Jet A fuel in a square pan is used for this scenario. The pan is 

constructed of 1/8-inch (0.3-cm) steel and measures 2 feet by 2 feet by 4 inches high (60.9 by 

60.9 by 10.2 cm). Approximately 13 fluid ounces (385 ml.) of gasoline should be added to the 

pan to make ignition easier. Two and one-half gallons (9.5 liters) of water placed in the pan has 

been found to be useful in keeping the pan cool and minimize warping. This quantity of fuel and 

pan size is sufficient to burn vigorously for approximately 4 minutes if not suppressed. The pan 

should be positioned in the cargo compartment in the most difficult location for the particular 

suppression system being tested. The pan is located 12 inches below the cargo compartment 

ceiling if the suppression system uses a gaseous agent with a density greater than air at standard 

pressure and temperature (14.7 psia (101.3 kPa), 59.0°F (15°C)). The pan is 12 inches (30.5 cm) 

above the floor of the compartment if the suppression system uses a gaseous agent with a density 

less than air at standard pressure and temperature. The pan is placed in the compartment at mid 

height when the suppression agent has a density equal to that of air. The pan is located at the 

maximum horizontal distance from any discharge nozzles for all tests, regardless of the 

suppression agent used (see figure 7). 

4.3.4 Aerosol Can Explosion Simulation. 

This scenario addresses the hazards of an exploding aerosol can during an aircraft cargo 

compartment fire. This test protocol uses a modified version of the bulk-load fire test scenario to 

determine the activation time of the aerosol can simulator. Based on experiments with aerosol 

cans subjected to fires, the FAA William J. Hughes Technical Center developed an aerosol can 

simulator (figures 8 and B-1 in appendix B) that releases a mixture of propane and alcohol 

through a large-area valve and across sparking electrodes [1]. This specific test protocol may be 

5
substituted with the shorter protocol version specified in section 4.3.5. For example, the shorttest protocol version may be used with gaseous fire suppression agents or if the system does not 

have unique capabilities, such as thermodynamic cooling that would need to be demonstrated 

during a fire test. 

The cargo compartment is loaded with corrugated cardboard boxes, galvanized steel pipes, and 

the aerosol can explosion simulator. Each box is a single-wall corrugated cardboard box with 

nominal dimensions of 18 by 18 by 18 inches (45.7 by 45.7 by 45.7 cm). The weight per unit 

area of the cardboard is 0.11 lbs/ft2

 (0.5417 kg/m2). The boxes are filled with 2.5 pounds 

(1.1 kg) of loosely packed standard weight office paper shredded into strips (not confetti) 

weighing 4.5 ±0.4 pounds (2.0 ±0.2 kg). The flaps of the boxes are tucked under each other 

without using staples or tape. The boxes are stacked in two layers in the cargo compartment in a 

quantity representing about 10% of the cargo compartment empty volume. For a 2000-cubicfoot (56.6-m3

) compartment, this requires 58 boxes. The boxes touch each other to prevent any 

significant air gaps between boxes. The boxes are arranged as shown in figure 9. Three 

galvanized steel pipes, with a thermocouple attached to the outer surface (centered) of each pipe, 

is inserted (one per box) in the boxes adjacent to the box above the ignition box. The schedule 

80 pipes are 8.25 inches (20.96 cm) long and have an outer diameter of 1.75 inches (4.45 cm). 

The main function of the three galvanized steel pipes is to hold the thermocouples in place rather 

than simulating the heating of an aerosol can. The fire in the box is initiated by applying 115 

Vac to a 7 foot (2.1 m) length of nichrome wire. The wire is wrapped around four folded (in 

half) paper towels. The resistance of the nichrome igniter coil is approximately 7 ohms. The 

igniter is placed into the center of a box on the bottom outside row of the stacked boxes. Several 

ventilation holes are placed in the side of the box to ensure that the fire does not self-extinguish. 

Ten 1.0-inch (2.5-cm) -diameter holes have been shown to be effective (see figure 3). 

The aerosol can explosion simulator is placed near the centerline of the cargo compartment (as 

long as there is no agent impingement on the simulator or electrodes), at least 5 feet (1.52 m) 

forward from the boxes, aft of the boxes containing the igniter and pipes. The unit could also be 

mounted outside the compartment, with the discharge port inside the compartment, to prevent 

heat damage; but the location of the igniter, with relation to the simulator discharge port, must be 

maintained. The simulator’s sparking electrodes are located 3 feet in front of the simulator 

discharge port and 2 feet above the floor. The simulator has a cylindrical pressure vessel for 

storing the base product hydrocarbon propellant. The pressure vessel is capable of withstanding 

a minimum pressure of 300 psi (2068.5 kPa). The pressure vessel has a ball valve to rapidly 

discharge the propellant, capable of withstanding a minimum pressure of 300 psi (2068.5 kPa). 

The port diameter of the ball must be 1.5 inches (3.8 cm) (note: a ball valve is typically 

classified according to the diameter of the pipe that it connects to, but this is not necessarily the 

size of the ball port). The ball valve is capable of rotating from the fully closed position to the 

fully open position in less than 0.1 second in order to form a vapor cloud. Longer opening 

durations will significantly affect the size of the vapor cloud formed and, hence, the explosive 

force. The ball valve can be activated by any suitable means, including pneumatic or hydraulic 

actuators or manually via the appropriate linkage. The pressure vessel is mounted vertically 

above the ball valve to allow for complete expulsion of the liquid contents. A discharge elbow 

located vertically under the ball valve directs the contents horizontally (see figures 8 and B-1). 

6
The following list describes the major components of the aerosol can simulator. 

• Pressure Vessel. A steel 2-inch (5.1-cm) -diameter, 11-inch (27.9-cm) -long schedule 80 

pipe welded or capped at one end. 

• Ball Valve. The 2-inch (5.1-cm) valve is constructed of a material capable of 

withstanding interaction with ethanol and propane. A DynaQuip stainless steel valve has 

been found suitable for this application. 

• Ball-Valve Actuator. A pneumatic rotary actuator is suitable for quickly and reliably 

rotating the ball valve from closed to fully open. A Speedaire 90-degree actuator with a 

2-inch (5.1-cm) bore performs well. 

• Propellant Heater. A system for heating the pressurized propellant mix after transfer to 

the pressure vessel is provided. This could include a hot-air gun directed toward the 

pressure vessel, a hot-wire wrap, or other suitable means. 

• Pressure Gauge. A suitable device for measuring the pressure of the contents is installed 

on the simulator pressure vessel, capable of measuring the pressure to within ±5 psi 

(34.5 kPa). 

• Propellant Mix. The base product/propellant mix is 20% liquid propane (3.2 ounces 

[0.09 kg]), 60% ethanol (denatured alcohol, 9.6 ounces [0.27 kg]), and 20% water 

(3.2 ounces [0.09 kg]). The total weight of the base product/propellant mix is 16 ounces. 

• Spark Igniters. A set of direct current (DC) spark igniters is used to ignite the 

propellant/base product mix discharged from the pressure vessel. An ignition transformer 

capable of providing a 10,000-volt output has been found to be suitable for powering the 

igniters, which should be placed 36 inches (91.4 cm) from the point of discharge. The 

spark igniter gap is set at 0.25 inch (0.64 cm). The igniter should be protected from the 

rapidly discharged simulator contents by shielding it. A bent piece of sheet metal, like a 

ramp, provides adequate protection. 

The procedure for setting up the aerosol can explosion simulator is as follows. 

Weigh the empty aerosol can explosion simulator device on a suitable scale and zero the scale. 

Place 9.6 ounces (0.27 kg) of ethanol (denatured alcohol) and 3.2 ounces (0.09 kg) of water into 

the pressure vessel. Transfer 3.2 ounces (0.09 kg) of liquid propane into the pressure vessel. 

Remove all transfer lines and check final mass. Mount the simulator device in the forward 

compartment bulkhead in a manner that directs the discharge across the spark igniters. The 

simulator device discharge port and the spark igniter are 2 feet (60.9 cm) above the compartment 

floor, and the spark igniter is 3 feet away from the discharge port. The simulator device 

discharge port is located on the centerline of the aircraft, 5 feet forward of the first rows of 

cardboard boxes spanning the width of the compartment. Again, the simulator device may be 

placed outside the cargo compartment with the discharge port installed on the compartment 

bulkhead. Heat the pressure vessel to raise the pressure of the contents to 240 ±5 psi 

7
(1655 ±34.4 kPa). Activate the suppression agent/system and the aerosol can explosion 

simulator as described in section 4.5. 

4.3.5 Aerosol Can Explosion Simulation (Short Version). 

As previously explained, the shorter version of the aerosol can explosion simulation test protocol 

may be used for gaseous agents in lieu of the version specified in section 4.3.4. 

In the short version, the aerosol can explosion simulator device is placed inside the empty 

standard compartment (see figure 10). The simulator device is prepared as specified in section 

4.3.4. This test starts when the fire suppression agent is discharged. The simulator device is 

activated at least 2 minutes after agent discharge. The activation time is dictated by the 

measured volumetric concentration, within ±0.1% of the minimum protection concentration. 

The minimum concentration is measured 2 feet (60.9 cm) above the floor, near the sparking 

electrodes. The agent concentration must be measured during the test, and calculation of agent 

concentration based on the leakage rate is not permitted. The gas-sampling probe is 36 inches 

(91.4 cm) from the exit of the simulator device and 18 inches (45.7 cm) to the side of the spark 

igniters (starboard or portside). The applicant must demonstrate that the system is capable of 

providing sufficient agent, at least to maintain the minimum inert concentration. The exploding 

aerosol can test scenario shall be conducted for at least 180 minutes or until the simulator device 

is activated, whichever is shorter. 

4.4 IGNITION SOURCE. 

Two types of ignition sources are used during the execution of these tests, resistance heat and 

electrical arc.

4.4.1 Resistance Heat. 

Applying 115 Vac to a 7-foot length (2.13 m) of nichrome wire ignites the bulk- and 

containerized-load materials. The wire is wrapped around four folded (in half) paper towels. 

The resistance of the nichrome igniter coil is approximately 7 ohms. The igniter is placed in the 

center of the ignited box.

4.4.2 Electrical Arc. 

A set of DC arc igniters are used to ignite the fuel in the surface burning test and the 

propellant/base product mixture in the aerosol can explosion simulation test. The igniters are 

connected to a transformer capable of providing 10,000 volts and 23 mA output. The 

interchangeable ignition transformer is manufactured by Franceformer, model number 37.9 

(LAHV). The igniters are placed 36 inches (91.4 cm) from the point of discharge for the aerosol 

explosion simulation test. The igniters are placed about 0.25 inch (6.35 mm) above the surface 

of the fuel for the surface-burning scenario. The gap in between the two electrodes is 0.25 inch 

(6.35 mm).

8
4.5 SUPPRESSION SYSTEM DESIGN. 

Some aspects of the fire suppression system to be installed in an aircraft cargo compartment shall 

be based on the results of the MPS fire tests. For example, these test results will provide the 

required concentration levels to adequately suppress standardized cargo fires and a hydrocarbon 

explosion, based on quantitative measurements, and not extrapolated from the bay volume 

concentration. Extrapolation of data to account for the required duration and analysis for cargo 

load configurations may be acceptable provided there is sufficient test data to support the 

analyses. The agent concentrations for the required duration of a diversion, accounting for 

leakage rates in an empty cargo compartment, must be demonstrated to be equal to or greater 

than that established in the MPS tests. It should also be noted that the initial concentrations to 

knockdown the initial fire flames and the concentration to control the fire shall be determined, 

which could be different values. The method of measuring the concentration of agent in the 

required flight test shall not use the arithmetic average of the probes. 

The selected agent is required to be compatible with the aircraft material to prevent problems 

like corrosion. 

The following provides a synopsis of the required airplane design minimum fire protection when 

associated with the four MPS test scenarios. 

Airplane Design Minimum 

Knockdown Concentration is MPS 

Test-Demonstrated Maximum 

Concentration for Knockdown of: 

Airplane Design Minimum 

Sustained Concentration is MPS 

Test-Demonstrated Maximum 

MPS Test Concentration to: 

Bulk-Load Test Flames Maintain continued fire 

suppression 

Containerized-Load 

Test 

Flames Maintain continued fire 

suppression 

Surface-Burning Test Flames Prevent reignition of Class-B fire

Aerosol Can Explosion 

Simulation 

Flames (long version) Prevent hydrocarbon explosion 

The minimum agent concentration or system configuration (in the case of nongaseous systems) 

shall be dictated by the fire protection system performance during the MPS tests. The basic 

(knockdown and sustained) suppression concentration requirements will be established during 

the MPS tests. As mentioned before, the volumetric concentration is based on an empty 2000- 

ft3 cargo compartment. The minimum selected value or configuration shall be the one(s) that 

was (were) capable of suppressing/inerting all four MPS fire scenarios. The aircraft cargo 

compartment shall always be protected against any of the MPS-specified fire threats. Variable 

metrics of not only duration but also compartment size and leakage rate should be accounted for 

by maintaining objective measurement of minimum concentration of agent in the cargo 

compartment. To measure the concentration levels that will dictate the minimum concentration 

requirements that will be demonstrated on an aircraft, the suppression agents shall be measured 

in a nonfire test in a discharge that is identical to the agent discharge in an actual fire test. This 

9
will eliminate any possible effect from the by-products of combustion and fire on the gas/agent 

analyzer readings. 

4.6 SUPPRESSION SYSTEM ACTIVATION. 

For the bulk-load, containerized-load, and surface-burning fire scenarios, the suppression system 

is activated 60 seconds after any one of the ceiling-mounted thermocouples equals or exceeds 

200°F (93.3°C). 

For the aerosol can explosion simulation fire scenario (long version), the suppression system is 

activated 60 seconds after any ceiling thermocouple equals or exceeds 200°F (93.3°C) after the 

start of the fire. The aerosol can simulator device is activated 5 minutes after any thermocouple 

attached to the galvanized steel pipes inside the cardboard boxes reaches 212°F (100°C). In the 

event that the thermocouples attached to the pipes do not reach 212°F (l00°C) or the fire is 

completely extinguished, activation of the aerosol can simulator device is not required. The 

suppression system must not directly impinge upon or affect the normal operation of the aerosol 

can simulator device and electrodes. 

For the aerosol can explosion simulation fire scenario (short version), refer to section 4.3.5 for 

details. 

4.7 TEST DURATION. 

The duration of the bulk- and containerized-load fire scenario tests is 30 minutes after the 

activation of the suppression system. The fifth test of the bulk- and containerized-load fire 

scenarios must be conducted for at least 180 minutes and must ensure that the temperatures at the 

end of the test are stable or decreasing. If the system tested is a hybrid system (dual agent), the 

bulk- and containerized-load fire scenarios must be run for a minimum of 180 minutes. 

The surface-burning fire test is conducted for 5 minutes from the time the suppression system is 

activated. (Note: the surface-burning fire test self-extinguishes in less than 10 minutes due to 

the consumption of the Jet A fuel.) 

The aerosol can explosion simulation fire test shall be conducted for at least 180 minutes or until 

the aerosol can simulator device is activated, whichever is shorter. 

5. ACCEPTANCE CRITERIA. 

The acceptance criteria determine whether a suppression system passes or fails the MPS tests. 

The criteria depend on three factors: peak temperature, the area under the time-temperature 

curve, and evidence of explosion. The MPS bulk-load, containerized-load, and surface-burning 

tests use the peak temperature and area criteria, while the aerosol can explosion simulation test 

depends on the evidence of explosion. The time-temperature area is calculated by multiplying 

the temperature at a specific time by the time increment and then adding up all the areas 

calculated or integrating the temperature versus time curve. Table 1 provides the values of the 

pass/fail criteria. Figure 11 shows the critical times during a test for computing the acceptance 

criteria for the bulk- and containerized-load fire scenarios. 

10
The acceptance criteria for the bulk-load fire scenario is that the average of the five test peak 

temperatures shall not exceed 720°F (382°C), starting 2 minutes after the suppression system is 

initially activated until the end of the test. In addition, the average of the five tests peak areas 

under the time-temperature curve of the compartment thermocouples shall not exceed 

9940°F-min (5504°C-min). The area is computed from 2 minutes after the time of initial 

suppression system activation until the end of the test (30 minutes after the agent was 

discharged). 

The criteria for the containerized-load fire scenario is that the average of the five test peak 

temperatures shall not exceed 650°F (343°C), starting 2 minutes after the suppression system is 

initially activated until the end of the test. The average of the five test peak areas under the timetemperature curve shall not exceed 14,040°F-min (7,782°C-min). The area is computed from 2 

minutes after the time of initial suppression system activation until the end of the test 

(30 minutes after the agent was discharged). 

The acceptance criteria for the surface-burning fire scenario is that the average of the five test 

peak temperatures shall not exceed 570°F (299°C), starting 2 minutes after the suppression 

system is initially activated until the end of the test (5 minutes after the agent was discharged). 

In addition, the average of the five test peak areas under the time-temperature curve shall not 

exceed 1230°F-min (665°C-min) over the 5-minute interval following agent discharge. 

These criteria values for the bulk-load, containerized-load, and surface-burning fire tests were 

based on the Halon 1301 test data and computed using the analysis presented in appendix A. 

The criterion for the aerosol can explosion simulation scenario is that there is no evidence of an 

explosion or reaction. Evidence of an explosion or reaction includes deflagrations, flashes, and 

overpressures, etc. There shall be no overpressures (zero pressure rise). In addition, when the 

agent concentration is below its inert concentration, the explosion intensity and peak pressures 

shall not be greater than the values exhibited during an explosive event when no suppression 

agent is present in the compartment. To find more information on this subject, refer to 

reference 2. 

For systems tested using the diversion time (instead of the 30 minutes), the average peak 

temperature is determined by using the collected data that is between 2 minutes after discharging 

the agent and the diversion time. The average of the five test peak temperatures shall not exceed 

the values presented in table 1. For the peak area under the time-temperature curve, the 2- to 

28-minute boundaries and criteria apply.

Five tests must be conducted for each scenario. The peak temperature and area under the timetemperature curve must be determined for each test. The five test peaks shall be averaged and 

compared to the acceptance criteria values (pass/fail). To pass the MPS tests, the average of the 

new agent performance values shall be equal or less than the acceptance criteria values provided 

in table 1. Table 1 summarizes the acceptance criteria for the four fire tests.

11
6. REFERENCES.

1. T. Marker, “Initial Development of an Exploding Aerosol Can Simulator,” FAA report 

DOT/FAA/AR-TN97/103, April 1998. 

2. J. Reinhardt, “Behavior of Bromotrifluoropropene and Pentafluoroethane When 

Subjected to a Simulated Aerosol Can Explosion,” FAA report DOT/FAA/AR-TN04/4, 

May 2004. 

12
FIGURE 1. CARGO COMPARTMENT LAYOUT AND 

INSTRUMENTATION LOCATIONS 

FIGURE 2. BULK-LOAD FIRE TEST SETUP 

13
FIGURE 3. IGNITER BOX 

FIGURE 4. CONTAINERIZED-LOAD FIRE TEST SETUP 

14
FIGURE 5. LD-3 CONTAINER 

FIGURE 6. LD-3 CONTAINER ARRANGEMENT 

15
FIGURE 7. SURFACE-BURNING FIRE PAN 

FIGURE 8. SCHEMATIC OF AEROSOL CAN EXPLOSION SIMULATOR 

16
FIGURE 9. AEROSOL CAN EXPLOSION SIMULATION TEST SETUP 

FIGURE 10. AEROSOL CAN EXPLOSION SIMULATION TEST SETUP 

(SHORT VERSION) 

17
0

100

200

300

400

500

600

700

0 5 10 15 20 25 30 35 40

Time (minutes)

Temperature (degrees F)

Max Temperature

t2 = t1 + 1 minute. 

Suppression System Activation 

t3 = t2 + 2 minutes; 

Data use for analysis 

t1 = time when 

temperature ≥ 200°F 

t4 = t3 + 28 minutes or 

t4 = t3 +deviation time, End of test 

Data range use for analysis

FIGURE 11. ACCEPTANCE CRITERIA BOUNDARIES 

TABLE 1. ACCEPTANCE CRITERIA 

Fire 

Scenario 

Maximum 

Temp. 

°F (°C) 

Maximum

Pressure 

psi (kPa) 

Maximum 

Temp-Time Area

°F-min. (°C-min.) Comments 

Bulk Load 720 (382) Not 

Applicable

9940 (5504) Use the data that is between 2 

and 28 minutes after suppression 

system activation. See figure 11.

Containerized 

Load 

650 (343) Not 

Applicable

14,040 (7,782) Use the data that is between 2 

and 28 minutes after suppression 

system activation. See figure 11.

Surface Fire 570 (299) Not 

Applicable

1230 (665) Use the data that is between 2 

and 5 minutes after suppression 

system activation. 

Aerosol Can 

Explosion 

Simulation 

Not 

Applicable 

0.0 Not Applicable There shall be no evidence of an 

explosion. No enhancement of 

explosion at below inert 

concentrations. 

18
APPENDIX A─DETERMINATION OF ACCEPTANCE CRITERIA VALUES 

The following table contains the results of the MPS tests conducted with Halon 1301 as the fire 

suppression agent. The presented peak temperatures and peak areas were determined by using 

the data that falls between 2 and 28 minutes after the agent was discharged in the cargo 

compartment. The acceptance criteria values were determine by adding the maximum value 

attained during the five tests with the standard deviation of the data set and then rounded off. 

Bulk-Load Test 

ContainerizedLoad Test Surface-Burning 

Test 

Test Test ID 

Max. 

Temp. 

(oF) 

Max. 

Area 

(oF-min)

Max. 

Temp 

(oF) 

Max. 

Area 

Test ID (oF-min) Test ID 

Max. 

Temp 

(oF) 

Max. 

Area 

(oF-min)

1 081198T1 511 8002 082898T1 586 12845 111899T3 548 1184 

2 081298T1 431 8906 083198T1 577 13029 111899T4 539 1195 

3 081398T2 450 9097 090198T1 606 13136 111999T1 549 1203 

4 081498T1 382 8938 090298T1 520 11967 111999T2 514 1147 

5 081998T1 632 9453 090498T1 498 10996 111999T3 517 1153 

6 082198T3 461 8733 

Standard Deviation 86.4 483.4 46.1 907.5 16.8 25.1 

Maximum Value 632 9453 606 13136 549 1203 

Sum of Std. Dev. + Max. 718.4 9936.4 652.1 14043.5 565.8 1228.1 

ACCEPTANCE CRITERIA (oF) 720 9940 650 14040 570 1230 

ACCEPTANCE CRITERIA (oC) 382 5504 343 7782 299 665 

A-1/A-2
APPENDIX B─AEROSOL CAN EXPLOSION SIMULATOR DRAWINGS 

FIGURE B-1. AEROSOL CAN EXPLOSION SIMULATOR PARTS 

B-1
FIGURE B-2. L-BRACKET 

B-2
FIGURE B3. INTERFACE COLLAR FOR SIMULATOR 

B-3/B-4