NTSB Identification: CHI91LA157.
The docket is stored on NTSB microfiche number 44921.
Accident occurred Tuesday, May 14, 1991 in EAU CLAIRE, WI
Probable Cause Approval Date: 02/08/1993
Aircraft: PIPER PA-34-220T, registration: N8356B
Injuries: 2 Uninjured.

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

THE RIGHT MAIN LANDING GEAR COLLAPSED DURING THE LANDING ROLL. THE AIRPLANE VEERED TO THE RIGHT AND THE RIGHT WING CONTACTED A RUNWAY LIGHT. POST ACCIDENT INVESTIGATION REVEALED A FATIGUE FAILURE OF THE LANDING GEAR TRUNNION ON THE LOWER FILLET OF THE WEB ON THE TRUNNION. METALLURGICAL EXAM REVEALED THE FAILURE PROPAGATED FROM GRINDING MARKS MADE DURING THE MANUFACTURING FINISHING PROCESS. A SERVICE BULLETIN WAS ISSUED IN 1985 BY THE MANUFACTURER ADDRESSING THE INSPECTION OF THIS AREA FOR CRACKS.

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

THE INADEQUATE FINISHING PROCEDURES USED BY THE MANUFACTURER AND THE FAILURE TO COMPLY WITH THE MANUFACTURER'S BULLETIN.

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