We wrote a few weeks ago about a truck accident in Ohio where a tractor trailer crossed over the center line, killing 4 and injuring 6 who were riding in a bus for residents of a special needs center. News reports now indicate that the truck driver is now claiming that the truck began speeding up by itself and that it was moving side to side on its own before he started hitting the brakes.My initial impression was that the accident was due to the truck traveling at excessive speeds in adverse weather conditions when federal regulations require that speed be reduced. With the new information contained in this news report, it appears that the culprit may be a mechanical issue.The true causes of truck accidents are many times not what they appear to be at first blush. This appeared to be a truck crash caused by excessive speed; now it appears to be caused by mechanical problems.Because the root cause of truck accidents are often not readily apparent, our practice is to issue a preservation letter to insurance companies and trucking companies to preserve records and other physical evidence relating to a truck accident, and this includes the power unit, the trailer, and all of its mechanical components. Without a preservation letter on file with the trucking company and its insurer, they would have been free to repair the truck and put it back into service. In doing so, it would have at least potentially destroyed the evidence needed to show mechanical failures as the cause of the truck accident.This is why we recommend to victims of truck accidents and their families that they retain an experienced truck accident lawyer when there is a truck accident involving serious injuries or wrongful death.