Aviation Accident Summaries

Aviation Accident Summary FTW89FA107

HENRYETTA, OK, USA

Aircraft #1

N64652

PITTS S-1S

Analysis

POWER LOSS OCCURRED DUE TO SEPARATION AND DEPARTURE OF LOWER 1/2 RT EXHAUST STACK. PLT MADE A FORCED LANDING ON THE 2 NORTHBOUND LANES OF A DIVIDED HWY. ON SHORT FINAL, THE ACFT STRUCK POWER LINES, CRASHED, AND SLID INTO A TRUCK TRAVELLING NORTH. A PASSENGER CAR, TRAVELLING SOUTH, BECAME ENTANGLED IN THE WIRES AND WAS SUBSEQUENTLY REAR ENDED BY ANOTHER BEHICLE. THE POWER LINE POLES WERE MASKED FROM VIEW BY TREES ON BOTH SIDES OF THE ROAD. EXAMINATION OF THE EXHAUST STACK REVEALED THAT IT HAD UNDERGONE EXTENSIVE POST-MANUFACTURE REPAIRS IN THE AREA OF THE SEPARATION. THERE WAS EVIDENCE OF EXTENSIVE WELD FUSION ZONE POROSITY IN THE AREA THAT HAD BEEN WELDED. WELD FUSION ZONE POROSITY HAS BEEN ATTRIBUTED IN THE PAST TO POOR SURFACE PREPARATION AND WELD REPAIR TECHNIQUES.

Probable Cause and Findings

AN ENGINE POWER LOSS DUE TO THE SEPARATION AND DEPARTURE OF AN EXHAUST STACK. THE STACK FAILED DUE TO POOR WELD. FACTOR(S) WAS: THE TERRAIN CONDITIONS OF THE SELECTED FORCED LANDING SITE.

 

Source: NTSB Aviation Accident Database

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