Crash Simulation of Transport Aircraft for Predicting Fuel Release   First Phase—Simulation of the Lockheed Constellation Model L-1649 Full-Scale Crash Test

For nearly 40 years, the National Fire Protection Association, the Federal Aviation Administration, and the International Civil Aviation Organization have used mathematical models, such as the Theoretical Critical Area and Practical Critical Area (TCA/PCA) method, to determine Aircraft Rescue and Firefighting (ARFF) requirements at commercial airports throughout the world. These models used the length and width of the aircraft fuselage to determine a rectangular area in which extinguishing the fire was critical to safely evacuate passengers. They do not consider the plausible amount of fuel that could be released in survivable crash events.

There has been growing concern that the ARFF requirements may not be sufficient for modern aircraft designs that include larger fuel capacities and varied crashworthiness. This research program is being conducted to establish an alternative methodology for evaluating the quantity of fuel dispersed during various types of survivable aircraft accidents and ultimately to contribute to the development of an alternative to the TCA/PCA method. The approach is to simulate survivable crashes using high-fidelity nonlinear dynamic finite element analysis of these events with fuel explicitly modeled in the wing tanks. The simulated, time-dependent fuel distribution will serve as input to fire modeling efforts for determining ARFF requirements. This research is being conducted in multiple phases. The first phase is a methodology validation phase in which a full-scale crash test of a Lockheed Constellation Model L-1649 is simulated. The objective of this phase was to demonstrate that this modeling approach can produce accurate results. Subsequent phases will implement the validated methodology for assessing fuel dispersal from two different transport aircraft.

This report describes the analysis methodologies and results of the first phase of the research program. The analyses successfully demonstrated that accurate predictions for fuel release in survivable accidents can be achieved by using high-fidelity nonlinear dynamic finite element analysis of these events. Overall, simulated and test results for the liquid released are in good agreement. Refinements of modeling methods to more accurately simulate full-scale crashes of modern transport aircraft for predicting fuel release were also determined.

DOT/FAA/TC-12/43
Authors: R.T. Bocchieri, R.M. MacNeill, C.N. Northrup, and D.S. Dierdorf