Narrative:

Aircraft was leveled at cruise altitude and phx approach was contacted for VFR TCA clearance to land at phx sky harbor. Power was reduced to cruise, at which time a heavy vibration accompanied by a loud banging came from the engine area. I further reduced power until vibration and noise levels reached a reasonable level. At the reduced power setting, smoke started entering the cabin and I was unable to hold the altitude assigned by phx approach. At that time I requested vectors to stellar airpark and declared an emergency to approach. By the time I reached stellar, the smoke had cleared. Although still losing altitude, I decided that sufficient height remained to continue to my original destination, where rescue equipment was available (stellar is unattended). Clearance to do so was requested and granted by phx approach. The subsequent landing at phx was uneventful, although smoke started again on final and tower was too busy with routine traffic to respond to my request for a fire observation. Aircraft was shut down and towed to the hangar. Subsequent inspection found an exhaust pipe had cracked and separated at the flange, allowing hot exhaust to begin burning oil residue on the cowling and engine. Loud banging was the pipe and muffler assembly moving in the engine compartment. I should have caught this problem during preflight because my normal practice is to give each exhaust stack a vigorous shake. Complacency caused me to skip a thorough preflight on this occasion. ATC has not requested a report as yet, and none has been filed.

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Original NASA ASRS Text

Title: SMA PLT ENCOUNTERS ENGINE PROBLEMS NEAR PHX.

Narrative: ACFT WAS LEVELED AT CRUISE ALT AND PHX APCH WAS CONTACTED FOR VFR TCA CLRNC TO LAND AT PHX SKY HARBOR. PWR WAS REDUCED TO CRUISE, AT WHICH TIME A HEAVY VIBRATION ACCOMPANIED BY A LOUD BANGING CAME FROM THE ENG AREA. I FURTHER REDUCED PWR UNTIL VIBRATION AND NOISE LEVELS REACHED A REASONABLE LEVEL. AT THE REDUCED PWR SETTING, SMOKE STARTED ENTERING THE CABIN AND I WAS UNABLE TO HOLD THE ALT ASSIGNED BY PHX APCH. AT THAT TIME I REQUESTED VECTORS TO STELLAR AIRPARK AND DECLARED AN EMER TO APCH. BY THE TIME I REACHED STELLAR, THE SMOKE HAD CLRED. ALTHOUGH STILL LOSING ALT, I DECIDED THAT SUFFICIENT HEIGHT REMAINED TO CONTINUE TO MY ORIGINAL DEST, WHERE RESCUE EQUIP WAS AVAILABLE (STELLAR IS UNATTENDED). CLRNC TO DO SO WAS REQUESTED AND GRANTED BY PHX APCH. THE SUBSEQUENT LNDG AT PHX WAS UNEVENTFUL, ALTHOUGH SMOKE STARTED AGAIN ON FINAL AND TWR WAS TOO BUSY WITH ROUTINE TFC TO RESPOND TO MY REQUEST FOR A FIRE OBSERVATION. ACFT WAS SHUT DOWN AND TOWED TO THE HANGAR. SUBSEQUENT INSPECTION FOUND AN EXHAUST PIPE HAD CRACKED AND SEPARATED AT THE FLANGE, ALLOWING HOT EXHAUST TO BEGIN BURNING OIL RESIDUE ON THE COWLING AND ENG. LOUD BANGING WAS THE PIPE AND MUFFLER ASSEMBLY MOVING IN THE ENG COMPARTMENT. I SHOULD HAVE CAUGHT THIS PROB DURING PREFLT BECAUSE MY NORMAL PRACTICE IS TO GIVE EACH EXHAUST STACK A VIGOROUS SHAKE. COMPLACENCY CAUSED ME TO SKIP A THOROUGH PREFLT ON THIS OCCASION. ATC HAS NOT REQUESTED A RPT AS YET, AND NONE HAS BEEN FILED.

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.