OOSC, Part II, Item 14. i. Hubs - Hub Assembly

While stopping a truck to conduct an inspection, I observed one set of dual tires to be wobbling while traveling down the road. Due to my previous experience replacing wheel bearings and wheel seals, I could tell the nut that goes against the wheel bearings, which holds the hub assembly onto the spindle had come loose, thus causing the entire set of dual tires to be loose on the axle. There was not any visible oil leaking and the nut that holds the hub assembly onto the spindle is not an axle positioning part, but rather a hub assembly part.

I have worked multiple crashes in my tenure with the Texas Department of Public Safety in which the driver side set of duals, whether it be a truck tractor or trailer, where this exact scenario has occurred and the entire hub assembly comes loose from the spindle and hits a vehicle going the opposite direction. The same things occurs when all of the lug nuts come loose, however when this occurs both tires come loose at the same time and stay together. The amount of damage inflicted can be the same as a head on collision. One particular crash I investigated in which this occurred, the entire hub assembly, with the dual tires still attached, went completely into the cab of another vehicle going the opposite direction and pushed the passenger seat into the backseat. If there had been a front seat passenger, it would have been a fatality. Furthermore, if the nut holding the wheel bearings on is loose, this can increase heat and cause a fire or cause the race to become damaged and thus locking up the wheel completely. I've attached a brief video of the latest inspection when I discovered this, as well as a short clip of a YouTube video that shows what can happen when this event occurs. I have also attached a diagram showing more in depth what I am talking about. The diagram shows two separate nuts behind the dust cap, however if the out of service criteria just says nut, this will prevent confusion as to which nut has to be loose because an inspector will not be able to tell roadside which one is loose. There needs to be an out of service condition added which will place a vehicle out of service if the wheel bearing nut is loose.

I respectfully request an out of service condition be added into the hub section addressing this specific issue. "Any movement, other than normal tire rotation, in the hub assembly due to a loose wheel bearing nut or worn wheel bearings/races" or something along those lines. Thank you for your consideration in this matter.