On certain RV trailers, the grease fittings on the axles may not have been tightened properly. As a result, a fitting could separate and damage the pin that locks the axle nut in place. If the axle nut comes loose, the spindle and wheel could separate from the trailer A wheel separation could cause a loss of control and increase the risk of a crash. Additionally, a wheel that separates could also hit another person or vehicle.