GA small aircraft diverted to alternate when oil pressure dropped below normal range.

Attributes
ACN	96964
Time
Date	198810
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mae
State Reference	CA
Altitude	msl bound lower : 8500 msl bound upper : 8500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : fat
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Route In Use	enroute : direct enroute : on vectors
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 65 flight time total : 1337 flight time type : 1083
ASRS Report	96964
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Oil pressure dropped below normal range. Oil temperature and cylinder head temperature remained normal. We were in radio contact with fresno approach so we requested vectors to madera, ca airport and made a precautionary landing so that we could have an a and P mechanic check the cause of oil pressure loss. It was found that #6 cylinder had lost compression and pumped oil through that cylinder, out the breather vent. Repairs are now being made by aviation service, madera, ca.

Original NASA ASRS Text

Title: GA SMA DIVERTED TO ALTERNATE WHEN OIL PRESSURE DROPPED BELOW NORMAL RANGE.

Narrative: OIL PRESSURE DROPPED BELOW NORMAL RANGE. OIL TEMP AND CYLINDER HEAD TEMP REMAINED NORMAL. WE WERE IN RADIO CONTACT WITH FRESNO APCH SO WE REQUESTED VECTORS TO MADERA, CA ARPT AND MADE A PRECAUTIONARY LNDG SO THAT WE COULD HAVE AN A AND P MECH CHK THE CAUSE OF OIL PRESSURE LOSS. IT WAS FOUND THAT #6 CYLINDER HAD LOST COMPRESSION AND PUMPED OIL THROUGH THAT CYLINDER, OUT THE BREATHER VENT. REPAIRS ARE NOW BEING MADE BY AVIATION SVC, MADERA, CA.

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.