Narrative:

I was en route on a VFR flight to reposition the aircraft for a part 135 flight. I was the only soul on board. After 15-20 mins of flight, I noticed I was losing manifold pressure. The left engine seemed to be running smoothly, but I lost 5-6 inches of manifold pressure. Changing the throttle didn't change anything. After several mins, I noticed a brownish fluid leaking out of the left wing, outside of the engine. I decided that there was a problem with the turbo and it was heating the wing. I lost the left main and left auxiliary fuel gauges -- they went to '0.' then the stall warning came on. I shut the left engine down and feathered the propeller. I didn't see any evidence of a fire, so I proceeded to the next closest airport and landed. When I was taxiing in, I noticed a strong smell of fuel. When I shut the engine down, the left engine was leaking fuel. After I found some mechanics, we drained the left main and left auxiliary fuel tanks. When the engine was opened, we found that the exhaust manifold developed a hole, then broke clean through. This caused the fuel lines to rupture and burned some wiring. I was fortunate that I shut the engine down when I did because the fuel never ignited. An FAA inspector and a representative from the NTSB were surprised that it didn't ignite. Initially the only indication I had was the loss in manifold pressure. Once the fluid started leaking out of the wing, I decided to shut it down. If the fuel had ignited, I wouldn't be here today. Callback conversation with reporter revealed the following information: the reporter was flying a cessna 401 on a part 135 positioning flight. An FAA and an NTSB representative came by to see the aircraft. They reported to the reporter that there have been 5 other similar occurrences of this problem, some where the aircraft broke up in-flight. No action has been taken against the reporter.

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Original NASA ASRS Text

Title: A CESSNA 401 PLT HAD TO SHUT DOWN AN ENG WHEN ITS EXHAUST MANIFOLD BROKE. SUBSEQUENT DAMAGE BURNED WIRING AND BROKE A FUEL LINE.

Narrative: I WAS ENRTE ON A VFR FLT TO REPOSITION THE ACFT FOR A PART 135 FLT. I WAS THE ONLY SOUL ON BOARD. AFTER 15-20 MINS OF FLT, I NOTICED I WAS LOSING MANIFOLD PRESSURE. THE L ENG SEEMED TO BE RUNNING SMOOTHLY, BUT I LOST 5-6 INCHES OF MANIFOLD PRESSURE. CHANGING THE THROTTLE DIDN'T CHANGE ANYTHING. AFTER SEVERAL MINS, I NOTICED A BROWNISH FLUID LEAKING OUT OF THE L WING, OUTSIDE OF THE ENG. I DECIDED THAT THERE WAS A PROB WITH THE TURBO AND IT WAS HEATING THE WING. I LOST THE L MAIN AND L AUX FUEL GAUGES -- THEY WENT TO '0.' THEN THE STALL WARNING CAME ON. I SHUT THE L ENG DOWN AND FEATHERED THE PROP. I DIDN'T SEE ANY EVIDENCE OF A FIRE, SO I PROCEEDED TO THE NEXT CLOSEST ARPT AND LANDED. WHEN I WAS TAXIING IN, I NOTICED A STRONG SMELL OF FUEL. WHEN I SHUT THE ENG DOWN, THE L ENG WAS LEAKING FUEL. AFTER I FOUND SOME MECHS, WE DRAINED THE L MAIN AND L AUX FUEL TANKS. WHEN THE ENG WAS OPENED, WE FOUND THAT THE EXHAUST MANIFOLD DEVELOPED A HOLE, THEN BROKE CLEAN THROUGH. THIS CAUSED THE FUEL LINES TO RUPTURE AND BURNED SOME WIRING. I WAS FORTUNATE THAT I SHUT THE ENG DOWN WHEN I DID BECAUSE THE FUEL NEVER IGNITED. AN FAA INSPECTOR AND A REPRESENTATIVE FROM THE NTSB WERE SURPRISED THAT IT DIDN'T IGNITE. INITIALLY THE ONLY INDICATION I HAD WAS THE LOSS IN MANIFOLD PRESSURE. ONCE THE FLUID STARTED LEAKING OUT OF THE WING, I DECIDED TO SHUT IT DOWN. IF THE FUEL HAD IGNITED, I WOULDN'T BE HERE TODAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FLYING A CESSNA 401 ON A PART 135 POSITIONING FLT. AN FAA AND AN NTSB REPRESENTATIVE CAME BY TO SEE THE ACFT. THEY RPTED TO THE RPTR THAT THERE HAVE BEEN 5 OTHER SIMILAR OCCURRENCES OF THIS PROB, SOME WHERE THE ACFT BROKE UP INFLT. NO ACTION HAS BEEN TAKEN AGAINST THE RPTR.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.