As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST AFTER TAKEOFF, THE ENGINE STARTED TO RUN ROUGH AND LOST POWER. PILOT RETRACTED GEAR AND LANDED IN FIELD. INVESTIGATION REVEALED THE CRANKSHAFT FAILED BETWEEN NR 2 AND NR 3 CYLINDERS NTSB NR CHI98LA360. THE ENGINE IS STILL INSTALLED ON AIRCRAFT AWAITING OWNER DECISION TO REPAIR OR REPLACE AIRCRAFT.