Narrative:

I was instructing a private pilot student in the pattern at ramona, ca airport. Shortly after a routine takeoff (approximately over the departure end of the runway at about 200 AGL) smoke began to come from under the instrument panel. A moment later there was a pop noise and an exhaust sound. I immediately told my student, who had the microphone, to declare an emergency and let the traffic (uncontrolled, 3 planes in the pattern) know we were low and would be making a quick circle back to the runway. Rather than make a 180 degree turn back to the runway and risk a head-on with landing traffic, I thought a quick circle would be safer. After the radio call, I immediately turned off the master, at which time the smoke seemed to slow. The gear had already been retracted after the takeoff. I did not want to risk worsening the smoke and/or fire by turning the power back on, and time and traffic were so tight that I thought it safer to not try to hand crank the gear down and find it only partially down at touchdown. My objective was to get on the ground and out of the aircraft as soon as possible. The smoke worsened turning from the downwind to base position. We landed on centerline with no damage to runway or environment, only the belly of the aircraft and the propeller sustained damage. After stopping I turned off the fuel and mixture. After investigation it was discovered that the exhaust pipe broke away from the muffler and burned the cowling and the ducting into the cabin.

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Original NASA ASRS Text

Title: ON TKOF SMA EXPERIENCED SMOKE IN COCKPIT. GEAR HAD BEEN RETRACTED. MADE EMERGENCY GEAR UP LNDG.

Narrative: I WAS INSTRUCTING A PRIVATE PLT STUDENT IN THE PATTERN AT RAMONA, CA ARPT. SHORTLY AFTER A ROUTINE TKOF (APPROX OVER THE DEP END OF THE RWY AT ABOUT 200 AGL) SMOKE BEGAN TO COME FROM UNDER THE INSTRUMENT PANEL. A MOMENT LATER THERE WAS A POP NOISE AND AN EXHAUST SOUND. I IMMEDIATELY TOLD MY STUDENT, WHO HAD THE MICROPHONE, TO DECLARE AN EMER AND LET THE TFC (UNCONTROLLED, 3 PLANES IN THE PATTERN) KNOW WE WERE LOW AND WOULD BE MAKING A QUICK CIRCLE BACK TO THE RWY. RATHER THAN MAKE A 180 DEG TURN BACK TO THE RWY AND RISK A HEAD-ON WITH LNDG TFC, I THOUGHT A QUICK CIRCLE WOULD BE SAFER. AFTER THE RADIO CALL, I IMMEDIATELY TURNED OFF THE MASTER, AT WHICH TIME THE SMOKE SEEMED TO SLOW. THE GEAR HAD ALREADY BEEN RETRACTED AFTER THE TKOF. I DID NOT WANT TO RISK WORSENING THE SMOKE AND/OR FIRE BY TURNING THE POWER BACK ON, AND TIME AND TFC WERE SO TIGHT THAT I THOUGHT IT SAFER TO NOT TRY TO HAND CRANK THE GEAR DOWN AND FIND IT ONLY PARTIALLY DOWN AT TOUCHDOWN. MY OBJECTIVE WAS TO GET ON THE GND AND OUT OF THE ACFT ASAP. THE SMOKE WORSENED TURNING FROM THE DOWNWIND TO BASE POSITION. WE LANDED ON CENTERLINE WITH NO DAMAGE TO RWY OR ENVIRONMENT, ONLY THE BELLY OF THE ACFT AND THE PROP SUSTAINED DAMAGE. AFTER STOPPING I TURNED OFF THE FUEL AND MIXTURE. AFTER INVESTIGATION IT WAS DISCOVERED THAT THE EXHAUST PIPE BROKE AWAY FROM THE MUFFLER AND BURNED THE COWLING AND THE DUCTING INTO THE CABIN.

Data retrieved from NASA's ASRS site as of August 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.