First-quarter accident statistics involving U.S.-registered aircraft released yesterday by Boca Raton, Fla.-based Robert E. Breiling Associates show the number of accidents among business turboprops has nearly doubled over the year-ago period. In the first three months of this year, there have been 15 turboprop accidents, three of which were fatal, resulting in a total of seven deaths. In the same period last year, there were eight turboprop accidents, three of which were fatal. The aircraft charter segment saw the largest deterioration, rising from two nonfatal accidents in the first quarter of last year to 10, including one fatal, in the first three months this year. The business jet category saw just a single accident so far this year, the January 5 crash of a Learjet 35A near Chicago that killed two pilots, compared with three nonfatal crashes in the same time frame a year ago. Last year’s lone fatal accident involving a U.S.-registered business jet occurred on December 17.