Development of a Firefighting Agent Application Test Protocol for Aircraft Fuselage Composites, Phase I—GLARE
A research effort is underway to develop a standardized test method to determine the amount of firefighting agent needed to extinguish fires involving aircraft built with advanced composite materials. These tests focus on evaluating the behavior of GLAss-REinforced aluminum laminate (GLARE) when exposed to a simulated aviation fuel-fed pool fire. This test is a continuation of previous carbon fiber-reinforced plastic fire tests reported in DOT/FAA/TC-12/6, “Development of a Firefighting Agent Application Test Protocol for Aircraft Fuselage Composites, Phase I—Carbon Fiber.”
This series of tests assessed the fire behavior of GLARE samples that are representative of aircraft skin applications. These tests focused on determining (1) if the temperature transfers through the sample, (2) if burnthrough or post-exposure burning occurs, (3) if a smoldering condition exists after fire exposure, (4) the amount of time it takes for the sample to naturally cool below 300°F (149°C) after the fire source is removed, and (5) if there are any physical indicators that would help firefighters determine if the sample has cooled sufficiently to prevent re-ignition.
The Federal Aviation Administration NextGen Burner was used as the fire source. It generates temperatures just over 1800°F (990°C), which are similar to that of an aviation fuel-fed pool fire. Twelve tests were conducted using GLARE 3-5/4-0.3, with a total thickness of 2.5 mm (0.098 in.). Nine of these tests used a 12- by 18-inch sample positioned flat, with the face of the sample in front of the fire source. The remaining three tests used the same size sample cut into four equal pieces layered 0.75 inch apart and set with the edges of the long side facing the fire source. The samples were subjected to different fire exposure times. Temperature measurements and infrared images were collected during the tests.
The nine flat panel tests measured the temperature on both sides of the sample, and the temperature measured on the back of the sample was less than half of the burner side temperature. Burnthrough did not occur during any of these tests. In each test, the outer layer of aluminum that faced the burner melted away, but the glass layers below remained mostly intact. There was some amount of post-exposure flame in all tests performed. Despite the exposure duration, the post-exposure flame lasted approximately 1 minute. The recorded times for the flat panel test samples to cool below 300°F (149°C) were not consistent. However, for the layered tests, the recorded times were consistent with an average time of 11 minutes 36 seconds. There were no visual indications that the samples had cooled below 300°F (149°C).
DOT/FAA/TC-14/23
Authors: John C. Hode and William Doig