Narrative:

Approximately 35 minutes after takeoff we noticed the right engine oil quantity indicated 12 quarts. Since we had just had maintenance performed on the left engine oil pressure system (oil pressure sensor) we suspected a problem. After another 10 minutes of flight the oil quantity indicated 10; oil pressure and temperature remained constant and normal. The first officer and I discussed returning to the departure airport or an en route stop for maintenance. I called dispatch and maintenance control; all agreed return to the departure airport was best for maintenance and passenger service. Air traffic control approved a turn direct turn back to the departure airport. ATC approved fuel dumping in their airspace and we dumped fuel. Even with the fuel dump it became apparent we were going to land over weight so an emergency was declared. We elected not to stay airborne and burn more fuel because we did not know how long we could run the left engine before all oil was lost. On base leg and final approach the oil quantity was 3 quarts during the landing roll out while in reverse thrust oil quantity went to 0. Stopped on runway and rescue vehicles inspected aircraft. No external damage was seen so we taxied to the gate. Over weight landing info: landing weight 329;000; vref 152; touchdown speed 157; vertical speed 200 -300 FPM; braking thrust reversers only till 80 KTS then medium braking to a stop on the runway. Kudos to both first officers for their assistance on checklist and analyzing all possible scenarios of the approach landing and possible go around.

Related reports:

Google
 

Original NASA ASRS Text

Title: During the flight following a B767 oil pressure sense unit replacement; the crew returned to the the departure airport because of oil quantity loss.

Narrative: Approximately 35 minutes after takeoff we noticed the right engine oil quantity indicated 12 quarts. Since we had just had maintenance performed on the Left Engine Oil Pressure System (oil pressure sensor) we suspected a problem. After another 10 minutes of flight the oil quantity indicated 10; oil pressure and temperature remained constant and normal. The First Officer and I discussed returning to the departure airport or an en route stop for maintenance. I called Dispatch and Maintenance Control; all agreed return to the departure airport was best for maintenance and passenger service. Air Traffic Control approved a turn direct turn back to the departure airport. ATC approved fuel dumping in their airspace and we dumped fuel. Even with the fuel dump it became apparent we were going to land over weight so an emergency was declared. We elected not to stay airborne and burn more fuel because we did not know how long we could run the left engine before all oil was lost. On base leg and final approach the oil quantity was 3 quarts during the landing roll out while in reverse thrust oil quantity went to 0. Stopped on runway and rescue vehicles inspected aircraft. No external damage was seen so we taxied to the gate. Over weight landing info: Landing weight 329;000; Vref 152; Touchdown speed 157; Vertical speed 200 -300 FPM; Braking Thrust Reversers only till 80 KTS then medium braking to a stop on the runway. Kudos to both First Officers for their assistance on checklist and analyzing all possible scenarios of the approach landing and possible go around.

Data retrieved from NASA's ASRS site as of July 2013 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.