L.A. Asadourian

During the period that fire-detection and extinguishing tests of the CV-340 power plant were in progress, the installation was also studied with respect to its fire resistance. Air flow and leakage in the power and accessory sections were studied with the aid of a dye introduced into the air stream upwind of the nacelle under simulated flight conditions. The dye technique proved to be a practicable means of detecting loose fits between mating parts. Test fires in the nacelle revealed which materials and components are most likely to fail during a power-plant fire. In many respects, the nacelle was exceedingly well constructed from the standpoint of fire safety. This was due in part to the unique design and to the generous use of stainless steel. However, the sealing materials used between mating surfaces were found to be 'vulnerable with the result that the confinement of fires was not successful. The destruction of certain seals permitted some fires to extend to the outside of the nacelle, a fact which complicated the extinguishment problem. A change in fabricating materials of one or two items of equipment are recommended.

J.A. Wilson

The ultimate goal in this field of endeavor is a complete knowledge of the surface flammability property of materials under varied fire conditions and appropriate methods to evaluate this surface flammability.

Charles A. Hughes & C. M. Middlesworth

A bromochloromethane fire-extinguishing system, designed by Walter Kidde & Company, Inc. in accordance with USAF Specification MIL-E-5352, was fabricated and installed in an XB-45 airplane power plant. Fire-extinguishing tests were conducted under simulated flight fire emergency conditions to check the validity of certain phases of the specifications and of certain design practices. Quantity requirements for extinguishing fires in each nacelle compartment were determined for bromochloromethane and dibromodifluoromethane.

Present design practices were found to result in a system, which meets the requirements of MIL-E-5352 specification for the duration of agent discharge and for agent distribution. The quantity of agent required by the specification (48.82 pounds) was found to be inadequate for extinguishing all nacelle fires. The minimum quantity of agent for extinguishing all fires was determined by test to be 66 pounds.

A system designed for bromochloromethane proved satisfactory for use with dibromodifluoromethane. On the basis of weight, the latter agent was somewhat more effective.

J.J. Gassmann

In order to provide industry with a uniform, reproducible flame for comparing the sensitivity and flame resistance of fire and heat detectors, a burner was developed which was capable of producing a six inch diameter flame at temperatures of 1500 degree F and 2000 degree F with not more than 25 degree F variation over the entire cross sectional area of the flame.

Charles A. Hughes

Test fires were concluded in the fire zone of a jet powerplant in order to determine the minimum amounts of fire extinguishing agents required for extinguishment under different conditions of air flow through the zone. The tests were conducted with four extinguishing agents which were discharged through conventional and experimental systems; first, with the zone in its original condition, and later, with a lining in the lower portion of the fire zone to provide a smoother flow of air.

Results indicate that the rate of airflow influenced the amount of extinguishing agent required for extinguishing of the test fires. With the lining installed, the quantity of fire extinguishing agent required was approximately a linear function of the rate of airflow. Without the lining and at the lower rates of airflow, burning fuel fell to the bottom of the nacelle and collected between the structural members or ribs. This resulted in increased extinguishing agent requirements. The results also indicate the effectiveness of each of the four extinguishing agents tested and provide a comparison between the two systems.