BETHEL, AK, USA
N7864F
CESSNA 401
THE ACFT RIGHT ENGINE STARTED EMITTING SPARKS FROM THE COWLING DURING NORMAL CRUISE. THE PILOT NOTED A DROP IN MANIFOLD PRESSURE SO HE REDUCED POWER ON THAT ENGINE AND THE SPARKS STOPPED. THE ACFT WAS LANDED AT BETHEL. THE FIRE DEPT. USED A FIRE EXTINGUISHING AGENT ON THE ENGINE. THE DAMAGE WAS MINOR. INSPECTION OF THE RIGHT ENGINE REVEALED A BROKEN BOLT ONTHE EXHAUST CLAMP WHICH SECURED THE EXHAUST PIPE TO THE TURBOCHARGER. THE CLAMP WHICH SECURED THE PIPE TO THE ENGINE NACELLE HAD SLIPPED OFF THE BRACKET. THIS ALLOWED THE PIPE TO SLIP DOWN AND RELEASE HOT EXHAUST GASES INTO THE ENGINE NACELLE. THIS HEATED THE ENGINE EXCESSIVELY AND REMOVED THE WASTE GATE FROM THE OPERATIONAL SYSTEM OF THE ENGINE. THE BROKEN BOLT IS A PART OF THE CLAMP P/N MVT 68637-375M.
Source: NTSB Aviation Accident Database
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