GA small transport engine failure at 4500'. Diverted to pmd.

Attributes
ACN	166118
Time
Date	199012
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pmd
State Reference	CA
Altitude	msl bound lower : 4500 msl bound upper : 4500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : pmd
Operator	general aviation : personal
Make Model Name	Small Transport
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 50 flight time total : 1200 flight time type : 4
ASRS Report	166118
Person 2
Affiliation	government : military
Function	controller : local
Qualification	controller : radar pilot : military
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable other
Consequence	other
Supplementary
Primary Problem	Aircraft

Narrative:

13 mi southeast of palmdale, engine started to fail, backfiring through air intake, missing and severe loss of power. Cockpit check revealed normal fuel pressure, oil pressure, temperature, mags ck ok. Called palmdale tower and got permission to land, declared emergency and made straight in approach. Landed with 50 percent power and engine running smoothly, further inspection on ground revealed failed exhaust valve #6 cylinder and total destruction of cylinder. Engine was overhauled approximately 20 hours ago.

Original NASA ASRS Text

Title: GA SMT ENGINE FAILURE AT 4500'. DIVERTED TO PMD.

Narrative: 13 MI SE OF PALMDALE, ENG STARTED TO FAIL, BACKFIRING THROUGH AIR INTAKE, MISSING AND SEVERE LOSS OF PWR. COCKPIT CHK REVEALED NORMAL FUEL PRESSURE, OIL PRESSURE, TEMPERATURE, MAGS CK OK. CALLED PALMDALE TWR AND GOT PERMISSION TO LAND, DECLARED EMER AND MADE STRAIGHT IN APCH. LANDED WITH 50 PERCENT PWR AND ENG RUNNING SMOOTHLY, FURTHER INSPECTION ON GND REVEALED FAILED EXHAUST VALVE #6 CYLINDER AND TOTAL DESTRUCTION OF CYLINDER. ENG WAS OVERHAULED APPROX 20 HRS AGO.

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.