Class D to C Conversions: A review of cargo fire detection/suppression requirements

Class D to C Conversions A review of cargo fire detection/suppression requirements By Greg Napert November 1999 Although the FAA has been addressing improving cargo compartments over the years, several incidents, along with...


Barfield's STC consists of a dual loop detection system certified to the one minute detection rule, two fire extinguishers with a metered second extinguisher for a one hour or ETOPS protection, and cockpit control panel with a system fault panel in the Electronics bay.

The suppression unit consists of two fire extinguishers, one diverter valve, one metering valve and supply lines and nozzles. The first extinguisher is a high-rate discharge bottle to knock down the fire. The second extinguisher is a metered low rate discharge bottle to regulate the flow of Halon and suppress the fire for a minimum of 60 minutes or longer for ETOPS.

Boeing has actually based certification of its smoke detection systems using Barfield's certification methodologies, says Barfield.

Walter Kidde Aerospace
Walter Kidde Aerospace, located in Wilson, N.C., offers the Kidde System 2000 for 2-bay narrow body aircraft and the System 3000 for 3-bay applications.

The company has STC certification for retrofit of the Boeing 737-200 aircraft and supplies LRU components for the factory Service Bulletin applications on the B727 and B737 models. In addition, all new "next-generation" B737-600/700/ 800/900 and remaining "classic" versions have Kidde LRU components installed at the factory.

Though the current requirements for the Cargo Fire Protection requirements do not mandate thermal detection, Kidde Aerospace offers this extra protection as a deterrent against low-smoke, hydrocarbon events such as a bursting aerosol container. In order to address the threat of false alarms, Kidde developed a new laborynth designed to offer enhanced differentiation between smoke, water and dust. It is standard on all Kidde System 2000, 3000 STC systems, as well as the detector utilized in the Boeing Class D to C Service Bulletin and production aircraft.

Kidde is presently completing fleet retrofits on all models of the B727, B737, DC9, DC-10, MD-80, F-28 and L-1011 aircraft.

Securaplane's Wireless
Wireless is an approach to fire detection taken by Securaplane Technologies in Tucson, AZ.

According to Mark Lukso, vice president of Securaplane, the company had been using wireless technology in its aircraft security products for years and saw an opportunity to apply it to fire detection systems. The company claims there are several advantages to using wireless technology in aircraft detection systems. The company claims there are several advantages to using wireless technology in aircraft detection systems.

  • Reduces wire count by 100 - 175.
  • Allows for a one day smoke detection/suppression system installation.
  • Reduces single point failures associated with wired systems.
  • Fire computation based on smoke and temperature detection.
  • Enhances maintainability through reduced wiring.
  • Saves 250 to 300 man hours installation time on a 737-300 over a wired system, according to Southwest

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The heart of Securaplane's wireless system is its Dual Central Control Unit that houses the receiver and calculates the probability of fire. Ext. 104 Walter Kidde; (252) 237-378 Ext. 232
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Securaplane's detectors sense smoke as well as temperature.


Further, Securaplane's approach to reducing false alarms by using smoke detection and temperature detection. Maintenance of Securaplane's system consists of testing the smoke sensors every 3,000 to 4,000 flight hours using artificial smoke, and cleaning the smoke chamber with compressed air and replacing batteries every three years. The company says it will take 8 to 10 minutes per sensor to remove and replace batteries and blow clean the easily accessible smoke detector chamber.

Avoiding false alarms
There is one factor which all of the parties selling these systems agree on — be sure that the system you are considering has a reputation for high quality.

When you consider the cost of landing at an alternate airport, deploying emergency slides, recharging and inspecting the suppression system, and paying for damages, it doesn't make sense to compromise on the quality of the system you invest in.

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