Materials: Thermal / Acoustic Insulation: Fuselage Burnthrough
Full-scale test results helped the FAA determine that modifying the existing thermal acoustic insulation was the most effective and practical means of achieving a burnthrough barrier. Comparative testing in the full-scale test rig had also shown that several alternative thermal acoustic insulation materials/systems were capable of significantly delaying the burnthrough process.
After the completion of full-scale testing, development of a laboratory-scale test for evaluating insulation burnthrough resistance was initialized. The new test needed to be realistic, yet simple enough to be conducted in a laboratory setting. The finalized test method utilizes an oil-fired burner, similar to those currently used for other fire test standards, including the seat fire-blocking test and the cargo liner burnthrough resistance tests. In order to replicate the heat flux and temperatures typical of a large fuel fire, the fuel and air flowrates of the oil burner were increased significantly over those used in the seat and cargo liner tests. Two insulation blankets are mounted in a steel test frame, which is situated at 4 inches from the end of the burner. The blankets are required to prevent flame passage for a period of 4 minutes. Lab tests were run on identical materials used in the full-scale tests. The finalized configuration used a 6-gallon-per-hour fuel flowrate, with a measured intake air velocity of 2150 ft/min. This test arrangement yielded excellent correlation to full-scale results.