1. Aircraft Cargo Compartment Fire Detection
International Aircraft Systems Fire Protection Working Group
Atlantic City, NJ
October 30-31, 2002
Aircraft Cargo
Compartment
Fire Detection
David Blake
FAA Technical Center
Atlantic City Airport, NJ
Phone:

2. Cargo Compartment Fire Detection Project
Objective:
- Standardize the fire(s) that should be detected (smoke, gas, heat output)
- Provide guidelines for the certification of newer technology detectors (multi sensor or other nuisance alarm rejection techniques) to reduce the false alarm rate (100:1)

3. Federal Aviation Regulation
Part Cargo Compartment Fire Detection Systems.
“If certification with cargo compartment fire detection provisions is requested, the following must be met for each cargo compartment with those provisions:
The detection system must provide a visual indication to the flight crew within one minute after the start of a fire.
The system must be capable of detecting a fire at a temperature significantly below that at which the structural integrity of the airplane is substantially decreased.
There must be means to allow the crew to check in flight, the functioning of each fire detector circuit.
The effectiveness of the detection system must be shown for all approved operating configurations and conditions.”

4. FAA Technical Standard Order (TSO) C1c 7/10/87
Cargo Compartment Fire Detection Instruments
References a Society of Automotive Engineers (SAE),
Aerospace Standard AS 8036
Type I: Carbon Monoxide, Alarm level 200 +/- 50 ppm.
Type II: Photoelectric, Alarm level 60-96% light transmission/foot.
Type III: Visual, Alarm level 70 +/- 10 % light transmission/foot.
Type IV. Ionization, Alarm level 60-96% light transmission/foot.

5. FAA Advisory Circular 25-9A
Smoke Detection, Penetration, and Evacuation Tests and Related Flight Manual Emergency Procedures.
Section 10.a.(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 asses the significance of a small amount of smoke.”

6. Target Smoke Level for Certification with Existing Regulations

7. False Alarm Issue
Source: FAA Service Difficulty Reports, FAA Accident/Incident database, NTSB reports.

10. The NTSB has issued numerous safety recommendations to the FAA based on a study conducted on aircraft emergency evacuations. One of the recommendations (A-00-91) is as follows:
“Document the extent of false indications for cargo smoke detectors on all airplanes and improve the reliability of the detectors.”
The FAA Administrator responded to the above recommendation in a letter dated 11/8/00. An excerpt from this letter is
“…the FAA is sponsoring a program to produce a standard means of testing detectors to demonstrate compliance with regulatory response requirements and to develop reliable aircraft smoke and fire detection systems that reduce the cargo compartment false alarm rate. The WJHTC tests will quantify typical gaseous compounds and particulate resulting from cargo fires that can be detected. These data can then be used to standardize the procedures used to certify multiple sensor cargo fire detection systems. The FAA has been working with the WJHTC to ensure that the information obtained from the testing will lead to the development of appropriate guidance and certification criteria.”

11. Starting point was the same quantity of smoke previously used in certification tests in small, narrow body cargo compartments.
707 Forward Compartment. 910 cubic feet
Rosco ml/min.

12. Fire Source Criteria
Good repeatability.
Immediate plume of smoke and gases.
Ability to generate all the products of combustion from actual luggage fires.
Ability to run the fire source in a cone calorimeter hood to accurately measure the heat release rate, mass loss rate and generation rate of the products of combustion.
Ability to remotely activate the fire source in an unoccupied compartment.

13. Standardized Fire Source
Nylon
Polyethylene
Polyurethane
Polystyrene
PVC
PBT
Standardized Fire Source

14. Smoldering Fire (Pyrolysis)
Spark Igniters, 2 ml heptane
Flaming Fire

15. SMOLDERING RESIN BLOCK
FLAMING RESIN BLOCK
ROSCO SMOKE GENERATOR

16. Resin Block/Rosco Location
707 Cargo Compartment
Ceiling Smoke Meters
Resin Block/Rosco Location

17. Smoke generated for 60 seconds
Smoke generated for 60 seconds. Smoke source stopped and a mixing fan was turned on for 4 additional minutes. The purpose of the mixing fan was to allow the measurement of the total quantity of smoke produced by eliminating buoyancy effects.

19. Smoldering Resin
Alarm Times (Seconds)
Detector A: 69
Detector B: 66
Detector C: 33
Detector D: 36
Detector E: 30
Detector F: 36
Resin Block

20. Resin Block Smoldering Resin Alarm Times (Seconds) Detector A: 101
Detector B: 69
Detector C: 64
Detector D: 85
Detector E: No alarm
Detector F: 119
3 different manufacturers detectors in recessed ceiling pan. Alarm points 95-96% light transmission per foot. Detector C was fan assisted. Power applied to resin block for 60 seconds.l

21. Flaming Resin
Alarm Times (Seconds)
Detector A: 56
Detector B: 150
Detector C: 39
Detector D: 45
Detector E: 32
Detector F: 36
Resin Block

22. Resin Block Flaming Resin Alarm Times (Seconds) Detector A: 70
Detector B: 61
Detector C: 52
Detector D: 65
Detector E: 81
Detector F: 100
3 different manufacturers detectors in recessed ceiling pan. Alarm points 95-96% light transmission per foot. Detector C was fan assisted. Power applied to resin block for 60 seconds.l

23. Cone Calorimeter with FTIR gas analysis

24. Cone calorimeter/FTIR

25. Cone calorimeter/FTIR

26. Cone calorimeter/FTIR

27. Cone calorimeter/FTIR

28. Cone calorimeter/FTIR

29. Cone calorimeter/FTIR

35. “Smoldering” fire source produces similar light obscuration values as previously used smoke sources for certification tests. It does not produce any other measurable fire signatures that could be used to discriminate between actual fires and nuisance alarm sources.

36. DC-10 Below Floor Cargo Compartment
Volume: 3500 cubic feet. Ventilation: 850 CFM
DC-10 Below Floor Cargo Compartment

37. Flaming Resin Detector Alarm Time A 1:40 B 1:12
C No Detection
D No Detection
Alarm time is the average of 2 tests.
Compartment volume = 3500 cubic feet
Ventilation=850 CFM
Flaming Resin
Resin Block

38. Flaming Resin Detector Alarm Time A 1:07 B 0:56
C No Detection
D No Detection
Alarm time is the average of 2 tests.
Compartment volume = 3500 cubic feet
Ventilation=850 CFM
Flaming Resin
Resin Block

39. Flaming Resin Block

41. Signatures of Various Fire Sources in 707 Lower Cargo Compartment.

48. AC 25-9A specifies “a smoldering fire producing a small amount of smoke” as the fire that should be detected within one minute. The origin of that statement was the desire to detect a fire before it could grow to a size that was uncontrollable. Not all fires transition through a small smoldering state. Ignition of flammable fluids goes directly into a flaming fire mode and may produce little smoke initially. This type of fire is more threatening to an airplane and would not be detected quickly with detectors that only respond to particulates.

49. Cargo Liner Burnthrough Test Requirement.
Minimum Flame Temperature: 1600° F.
Minimum Heat Flux: 7.5 BTU/ft2-sec.
Test Duration: 5 minutes
Approximate Heat Release Rate: 50 KW
Flaming Resin Heat Release Rate: 1 KW

50. Halon Replacement
Minimum Performance Standards
2’ X 2’ Pan Fire with 0.5 gallons Jet A
Must be Extinguished/Suppressed within 30 Seconds.
Approximate Heat Release Rate: 200 KW
Flaming Resin Heat Release Rate: 1 KW

51. Project Status
Flaming resin meets criteria for repeatability, generation of other fire signatures, remote activation and immediate plume.
Smoldering resin does not meet all criteria. True smoldering sources exist but also do not meet all criteria.
Flaming resin produces appropriate smoke and gases to be detected within one minute in small narrow body below floor compartments.
Flaming resin does not produce sufficient smoke and gases to be detected within one minute in large ventilated compartments.

52. Recommended Direction
Use the flaming resin block as the standard fire for detection.
Develop simulants for the smoke, heat and gases produced by the flaming resin block.
Scale appropriate detection time limits based on cargo compartment volume and ventilation rates.