Aviation Accident Summary ANC92FA005

MONTAGUE ISLAND, AK, USA

Aircraft #1

N3850Z

PIPER PA-18

Analysis

DURING CRUISE FLIGHT, THE ENGINE SEIZED WITHOUT WARNING. WITH NO SUITABLE LANDING AREA ON THE BEACH, THE PILOT DITCHED IN THE OCEAN AND SWAM ASHORE ABOUT 1/2 MILE AWAY. AN INVESTIGATION REVEALED THAT THE CRANKSHAFT HAD BROKEN AT THE FORWARD CHEEK OF THE #3 MAIN BEARING. A REDDISH SEALANT RESIDUE WAS FOUND AROUND THE MAIN BEARING THRU STUD HOLES OF THE CRANKCASE. ACCORDING TO LYCOMING SERVICE INSTRUCTION #1125A, SEALANT SHOULD NOT HAVE BEEN APPLIED IN THIS AREA.

Probable Cause and Findings

THE POWER LOSS DUE TO THE CRANKSHAFT FAILURE. CONTRIBUTING TO THE ACCIDENT WAS IMPROPER MAINTENANCE DURING THE LAST ENGINE OVERHAUL.

 

Source: NTSB Aviation Accident Database

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