Is this reasoning fallicious or faulty?

In a single vehicle work accident, the investigations team from the employer attributed the main cause for the accident to be operator error because they found the vehicle "to be in good working condition before and after the accident". The weather was fine and there was no DUI or willful act on the part of the operator.

Is it right to come to that conclusion?

I think to best answer this, one would have to have some specialized knowledge of automobile accidents. Having said that, I would think that to create a proper dichotomy, there is the operator, and everything else. If you can eliminate the probability of "everything else" then the operator is all that is left.* It appears that in the above example, "everything else" is limited to the working condition of the vehicle and the weather. But what about other drivers, animals, faulty traffic signs, natural or man-made obstacles in the road, etc.? From the description above, I would say the conclusion reached was premature ( hasty generalization ).

* This is one of ideas of Sherlock Holmes, which is also problematic. In short, it is generally impossible to eliminate "everything else" because we cannot know what everything else is. But that is why I said that an expert in the field of investigating accidents would best know what to look for and because the scope of "everything else" is limited in practice (i.e., we can reasonable rule out demonic possession of the operator, etc.).