HAYWARD, CA, USA
N11BU
CESSNA 421B
THE PILOT REPORTED THAT HE OVERPRIMED THE RIGHT ENGINE WHEN HE ATTEMPTED TO START IT. DURING THE START OPERATION, AN ACCUMULATION OF FUEL VAPOR LOCATED OUTBOARD OF THE RIGHT ENGINE EXPLODED AND RIPPED OPEN A YARD LONG PORTION OF THE RIGHT WING'S UPPER SKIN PANELS. EVIDENCE WAS OBSERVED OF AN UNCORRECTED PREEXISTING FUEL LEAK IN THE VICINITY OF THE RIGHT ENGINE'S AUXILIARY FUEL PUMP. THE PILOT REPORTED THAT HE WAS AN A & P MECHANIC, AND HE OWNED, OPERATED AND MAINTAINED THE AIRPLANE.
THE EXPLOSION OF FUEL VAPORS IN THE RIGHT WING DUE TO THE PILOT'S OVERPRIMING OF THE RIGHT ENGINE DURING A START ATTEMPT AND AN UNCORRECTED PREEXISTING FUEL SYSTEM LEAK. A FACTOR IN THE ACCIDENT WAS INADEQUATE MAINTENANCE PERFORMED ON THE AIRCRAFT.
Source: NTSB Aviation Accident Database
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