Original Date: 08/07/1995
Revision Date: 01/18/2007

Lockheed Martin Tactical Aircraft Systems (LMTAS) has developed a Fuel System Simulator (FSS) as an important tool in conducting aircraft fuel systems testing. Innovative design and fabrication procedures used in the design and building of simulated fuel tanks for the F-22 FSS are helping improve quality and lower program costs.

The FSS facilitates comprehensive systems level testing early in a development program and at a lower cost than conducting testing on a ground or flight test aircraft. The test article includes a shipset of actual aircraft plumbing such as pumps, valves, tubing and instrumentation. This plumbing is installed into a set of full-scale, simulated fuel tanks and monitored and controlled with aircraft processors and software. Test equipment is provided at the FSS to simulate aircraft ground and in-flight environments and other parameters that impact the operation of the fuel system. Equipment is also provided to allow in-flight and ground refuel testing and defueling. This FSS test equipment provides test conditions and allows the aircraft hardware and controls to respond to those conditions in a laboratory environment.

Design and fabrication of the integral fuel tanks used in the test setup is an historically time-consuming aspect of providing FSS. The tanks are normally simulations of the actual aircraft structure that constitute the fuel tanks, and are full scale and virtually duplicate aircraft tank volume, geometry, and any internal structural detail that may impact the performance of the fuel system. For the F-22 FSS, LMTAS developed less-manpower, lower-cost procedures to provide these simulated tanks. The procedures include using a two-dimensional simulation of the aircraft structural members making up the integral tanks, using full-scale templates in the fabrication of these structural members, and using a sheet metal roll-forming machine and the structural framework to form contoured, removable skin and inlet duct surfaces. Procedures in welding and sealing have been fine tuned to minimize warpage and leakage of the tank units.

These procedures result in design and build of simulated tanks that cost less, provide a higher fidelity simulation of the actual aircraft tanks to facilitate more accurate testing to predict performance, allow adequate access for installing, viewing and maintaining internally-installed aircraft hardware, and are more leak tight.

The more accurate duplication of the aircraft integral tank geometry and structure also allows better testing of the F- 22 on-board inert gas generating subsystem which is relatively new technology incorporated on this aircraft. These design and build procedure improvements provide a capability to perform more comprehensive testing earlier in the program and at a lower cost.

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