As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A CHECK FLIGHT ON NR 1 ENGINE, OPERATION AFTER MAINT OF MIXTURE ROD END REPLACEMENT PN 89307-000, THE NR 1 ENGINE FAILED. MAINT DISCOVERED THAT THE NR 5 CYLINDER CONNECTING ROD HAD BROKEN AND PENETRATED THE CRANKCASE. THE CAMSHAFT WAS ALSO FOUND TO HAVE BROKEN. ENGINE FAILURE DUE TO TRAILING COUNTERWEIGHT ATTACHMENT PIN BREAKAGE. THE COUNTERWEIGHT BECAME DISCONNECTED AND BROKE NUMEROUS ENGINE PARTS.