FOD (Foreign Object Damage) Generation by Aircraft Tires

Abstract : Lofting of loose debris by overrolling tires was investigated by experiments and analysis. Trajectories of lofted particles were determined with a stereoscopic camera system. Tire speeds ranged up to 40 mph; single-and dual- wheel carriages were used. Debris was mostly stones, 1 inch and smaller. Concrete and packed dirt surfaces, both wet and dry, were included. The probability of lofting a stone, given an encounter, was typically 15 percent, until the stone density exceeded one stone per footprint area; then the lofting probability was much less. Launch directions were mainly within 20 degrees of the direction defined by the wheel axle. Launch velocities were mainly less than 2.5 m/s. The probability of launching debris to above 4 was about 0.03. Angularity and size both increase lofting probability. Water did not greatly affect stone lofting, except for very small stones (6 mm). Extrapolations of these results to airfield scenarios predict that the danger of engine ingestion of nosewheel generated debris is minimal. The worst case considered was the F-4, which was less than 0.17 stones/km ingestion. These conclusions are based on extrapolations and need to be checked with experiments at higher tire speeds and loads.