The pilot of a Colgan Air Beech 1900 that crashed into the ocean off Cape Cod last Tuesday had declared an emergency and reported a problem with "runaway trim," according to preliminary reports. The pilot tried to return to the airport at Hyannis, Mass., but in less than two minutes hit the water at a 30-degree nose-down attitude, at 250 knots. Both pilots were killed. The NTSB said that during a routine maintenance check at Barnstable Municipal Airport the day before the crash, the airplane's two twin-tab actuators and a forward-elevator trim cable had been replaced. The accident reminded some of another fatal B1900 crash. Colgan Air, based in Manassas, Va., is a carrier for US Airways Express. The flight was bound to Albany, N.Y., for repositioning. There have been three fatal crashes involving Beech 1900D aircraft since 1998, according to FAA records, including a crash in January that killed 21 people in Charlotte, N.C., shortly after takeoff. Preliminary reports say a control cable in the North Carolina aircraft had been adjusted incorrectly shortly before the flight.