A B767-300ER declared an emergency and diverted when oil quantity began decreasing.

Attributes
ACN	648996
Time
Date	200503
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz1.artcc
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	cruise : level ground : maintenance
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	648996
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	648991
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : landed in emergency condition flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

After reaching cruise at FL370 I noted a decrease in oil quantity on the right engine. At that point; I called for the QRH procedure for the B767 aircraft and advised dispatch and maintenance technician of the problem. Maintenance advised us the engine was on aircraft for 150 hours and agreed with my divert decision then diverted to ZZZ and found 'B' nut had worked itself loose.

Original NASA ASRS Text

Title: A B767-300ER DECLARED AN EMER AND DIVERTED WHEN OIL QUANTITY BEGAN DECREASING.

Narrative: AFTER REACHING CRUISE AT FL370 I NOTED A DECREASE IN OIL QUANTITY ON THE R ENG. AT THAT POINT; I CALLED FOR THE QRH PROC FOR THE B767 ACFT AND ADVISED DISPATCH AND MAINT TECHNICIAN OF THE PROB. MAINT ADVISED US THE ENG WAS ON ACFT FOR 150 HRS AND AGREED WITH MY DIVERT DECISION THEN DIVERTED TO ZZZ AND FOUND 'B' NUT HAD WORKED ITSELF LOOSE.

Data retrieved from NASA's ASRS site as of January 2009 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.