Each of the complaints alleges that an internal failure of the steering gear box led to a complete loss of steering control. One owner claims that the steering failure caused him to crash into a parked vehicle, and another alleges that the fault is responsible for a collision with a guardrail.
The investigation affects 380,000 F-250 and F-350 trucks from the 2008 model year.
Ford is aware of the investigation and cooperating fully with the NHTSA, company spokeswoman Kelli Felker told The Detroit News.
The NHTSA is also currently looking into 195,000 2005-08 Ford Crown Victoria Police Interceptors to check for a separate steering issue. Those models may be at risk of total steering failure due to the separation of the upper and lower intermediate shafts within the steering column.