Primary finding
Probable cause
The following Probable Cause was modified on April18, 2007, as a result of new information provided to the NTSB. THE IMPROPER INSTALLATION OF THE 1.75 INCH OD PLUG IN THE CRANKSHAFT BY UNKNOWN MAINTENANCE PERSONNEL WHICH RESULTED IN AN INADVERTENT FEATHERING OF THE LEFT ENGINE PROPELLER.
Investigator assessment
Analysis narrative
The following Brief was modified on April18, 2007, as a result of new information provided to the NTSB. THE AIRCRAFT COLLIDED WITH A BRIDGE WHILE TRYING TO RETURN TO THE AIRPORT AFTER REPORTING AN EMERGENCY DURING THE PREVIOUS TOUCH AND GO LANDING. WITNESSES INDICATED BOTH ENGINES SOUNDED LIKE THEY WERE RUNNING AND BOTH PROPELLERS WERE TURNING. THE LEFT ENGINE PROPELLER WAS FOUND FEATHERED AFTER THE ACCIDENT. INVESTIGATION REVEALED A 1.75 INCH OD PLUG INSTALLED IN THE CRANKSHAFT TO SEPARATE OIL PRESSURE FROM THE PROPELLER GOVERNOR AND THE ENGINE CRANKCASE WAS BLOWN AFT DAMAGING THE NUMBER ONE ROD CONNECTING JOURNAL OIL TRANSFER TUBE. EXAMINATION OF THE PLUG DISCLOSED THAT IT WAS INSTALLED BACKWARDS.
Source record
Factual narrative
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