An small aircraft pilot had a partial engine failure. He was able to fly to his destination.

Attributes
ACN	236165
Time
Date	199303
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bxk
State Reference	AZ
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Route In Use	enroute airway : zab
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 560 flight time type : 390
ASRS Report	236165
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : provided flight assist controller : issued new clearance flight crew : overcame equipment problem other
Consequence	other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During normal cruise at 11000 on an IFR flight from oak, ca, to scottsdale, az, the engine of my small aircraft suddenly started running rough. This occurred 60-70 mi west of scottsdale on V16. I notified center that I had a problem by declaring 'pan, pan, pan.' I decided to proceed to the closest airport which was 40 mi east on V16 while attempting to diagnose the problem. Manifold pressure, RPM, fuel pressure, oil temperature, oil pressure, cylinder head temperature, and egt were all normal (and unchanged except for cylinder head temperature, which was in the low green). Magneto check did not change roughness, nor did mixture adjustment or ram air. The airplane maintained altitude easily at 11000, however, ground speed dropped 15-20 KTS to 125 KTS. In the next 20 mins, there were no changes in airplane performance. Because buckeye airport did not appear to have a repair facility according to my commercial handbook and because I believed that I could safely complete the flight, I requested and received from ATC 'clearance direct' to scottsdale. ATC cleared me to lower altitude as I approached the TCA, however, I requested and received clearance to remain at 11000 until I had visual contact with the field. I landed uneventfully and taxied to the FBO where the engine was evaluated and repaired. The exhaust valve on cylinder #3 had cracked.

Original NASA ASRS Text

Title: AN SMA PLT HAD A PARTIAL ENG FAILURE. HE WAS ABLE TO FLY TO HIS DEST.

Narrative: DURING NORMAL CRUISE AT 11000 ON AN IFR FLT FROM OAK, CA, TO SCOTTSDALE, AZ, THE ENG OF MY SMA SUDDENLY STARTED RUNNING ROUGH. THIS OCCURRED 60-70 MI W OF SCOTTSDALE ON V16. I NOTIFIED CTR THAT I HAD A PROB BY DECLARING 'PAN, PAN, PAN.' I DECIDED TO PROCEED TO THE CLOSEST ARPT WHICH WAS 40 MI E ON V16 WHILE ATTEMPTING TO DIAGNOSE THE PROB. MANIFOLD PRESSURE, RPM, FUEL PRESSURE, OIL TEMP, OIL PRESSURE, CYLINDER HEAD TEMP, AND EGT WERE ALL NORMAL (AND UNCHANGED EXCEPT FOR CYLINDER HEAD TEMP, WHICH WAS IN THE LOW GREEN). MAGNETO CHK DID NOT CHANGE ROUGHNESS, NOR DID MIXTURE ADJUSTMENT OR RAM AIR. THE AIRPLANE MAINTAINED ALT EASILY AT 11000, HOWEVER, GND SPD DROPPED 15-20 KTS TO 125 KTS. IN THE NEXT 20 MINS, THERE WERE NO CHANGES IN AIRPLANE PERFORMANCE. BECAUSE BUCKEYE ARPT DID NOT APPEAR TO HAVE A REPAIR FACILITY ACCORDING TO MY COMMERCIAL HANDBOOK AND BECAUSE I BELIEVED THAT I COULD SAFELY COMPLETE THE FLT, I REQUESTED AND RECEIVED FROM ATC 'CLRNC DIRECT' TO SCOTTSDALE. ATC CLRED ME TO LOWER ALT AS I APCHED THE TCA, HOWEVER, I REQUESTED AND RECEIVED CLRNC TO REMAIN AT 11000 UNTIL I HAD VISUAL CONTACT WITH THE FIELD. I LANDED UNEVENTFULLY AND TAXIED TO THE FBO WHERE THE ENG WAS EVALUATED AND REPAIRED. THE EXHAUST VALVE ON CYLINDER #3 HAD CRACKED.

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.