As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THE PILOT SMELLED EXHAUST FUMES IN THE CABIN WHILE IN CRUISE FLIGHT. THE PILOT THEN CLOSED THE HEATER CONTROL AND OPENED THE VENTS FOR FRESH AIR. THE PILOT THEN FLEW BACK TO THE BASE FOR THE ENGINEER TO INSPECT. THE ENGINEER FOUND A CRACK IN THE EXHAUST SYSTEM INSIDE THE HEAT SHROUD AT THE ELBOW WHERE THE EXHAUST EXITS THE MUFFLER. THE EXHAUST SYSTEM WAS THEN REPLACED WITH A NEW PART. (TC NR 20071114004)