Just how long do these reports take to generate? I've been looking for one from 9/2/2012 at KBJC and so far nothing yet, not even a prelim.
What do you enter for your search query ?
Early on when looking for prelims, it works best just to look by state without entering any other search terms. Unless the accident happened right on the airport, they dont usually put the airport identifier as the location but rather whatever geographic description applies to the zip code the wreckage came down in. So if you are looking for a crash that happened at 'OSH', it may be listed as 'Ripon, WI'. Also the fields 'fatal/nonfatal' are not allways entered for a prelim.
The same applies when looking for older reports, that is anyting prior to about 2000. On the really old ones, the city and state are a combined search field and they sometimes used abbreviations for towns that are not in common use today.
Also, some things we consider 'accidents' are 'incidents' in the NTSBs world. You can rip off the landing gear and fold the engine underneath the plane and they consider it only 'prop and landing gear damage' leaving the investigation stays on the FAA side of the fence.
The other thing to do is to widen the time window by a couple of days in either direction. Going to 9/1/2012 gives a stingsport crash in Longmont,CO which is reasonably close to BJC (CEN12LA655). Is that the one you are looking for ?