NTSB Identification: CHI89LA063.
The docket is stored on NTSB microfiche number 39116.
Accident occurred Sunday, March 26, 1989 in CROTHERSVILLE, IN
Probable Cause Approval Date: 07/11/1990
Aircraft: BEECH 95-B-55, registration: N27WF
Injuries: 2 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

DURING A LOCAL PLEASURE FLIGHT, WHILE IN NORMAL CRUISE, THE RIGHT ENGINE FAILED TOTALLY. THE PILOT REDUCED POWER ON THE LEFT (OPERATING) ENGINE TO 'CURTAIL THE VIOLENT VIBRATION OF THE AIRCRAFT' AND EXECUTED A FORCED LANDING IN AN OPEN FIELD. AS THE AIRCRAFT WAS ROLLING OUT AFTER TOUCHDOWN, IT ENCOUNTERED A MUDDY AREA. THE NOSE GEAR BOGGED DOWN, THEN COLLAPSED, AND THE AIRCRAFT NOSED OVER. POST-ACCIDENT EXAMINATION OF THE RIGHT ENGINE REVEALED THAT THE PIN RETAINING PLATE CUT THROUGH THE CRANKSHAFT COUNTERWEIGHT, RELEASING IT. FURTHER EXAMINATION REVEALED THAT THE COUNTERWEIGHTS HAD NOT BEEN 'TUFTRIDED', A SURFACE HARDENING PROCESS WHICH PREVENTS THE PIN RETAINING PLATE FROM CUTTING/WEARING THROUGH THE COUNTERWEIGHT. THIS PROCESS HAS BEEN REQUIRED ON NEW ENGINES SINCE 1968, AND ON REBUILT ENGINES SINCE 1973-74. THE ACCIDENT ENGINE WAS REBUILT BY THE MANUFACTURER IN 1971. LOGBOOK/MAINTENANCE INFORMATION PROVIDED BY THE PILOT WAS INCOMPLETE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A FAILURE OF THE ENGINE DUE TO A CRANKSHAFT COUNTERWEIGHT FAILURE. THE PILOT PERFORMED EMERGENCY PROCEDURES AND EXECUTED A FORCED LANDING IN AN OPEN FIELD, WHERE THE AIRCRAFT ENCOUNTERED A LARGE MUDDY AREA, BOGGED DOWN AND NOSED OVER.

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