Narrative:

Aircraft came in with a [logbook write-up] stating the left [engine] oil bypass light came on at landing. The crew who flew the plane in stated to the mechanics working the plane that the light flickered. Later that night the mechanics came to me and told me about the [logbook write-up] and the verbal from the crew. They stated they had inspected the delta P (differential pressure switch) and it had not popped for the oil filter; they also tried to remove the filter bowl to replace the filter and it was stuck. I got into the ipc (illustrated parts catalog) to see if we had the next higher component; the module that the filter bowl attaches to and we did not have one. In the meanwhile the mechanics went to the plane and cleaned the cannon plug and ran the engine and the bypass light did not re-illuminate. They came back in and told me about the situation and I dialed up maintenance control to tell them what was going on with the plane. I told maintenance control that the filter bowl was stuck and we would destroy it if we forced it any further plus we did not have the module 'next higher assembly'. Since we cleaned the plug; ran the engine and no delta P indication we; myself the mechanic and the controller; felt it was an indication issue; and we made the decision to clear the [logbook write-up]. I did not pull up the fim (fault isolation manual) that night and assumed that the mechanics did which I should have questioned when I reviewed the [logbook write-up] because of no mention of a fim or MM (maintenance manual) used to come to this conclusion. The plane left the next morning and while on climbout at 25;000 ft the light came on and the plane returned to the field. Once back day shift removed the module and cut the filter bowl off and the filter was clean. They then looked at the chips [detectors] and found the gearbox detector had debris and the engine was changed.

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Original NASA ASRS Text

Title: While troubleshooting an engine oil filter bypass light write up on a B737-700; Maintenance personnel were unable to remove the oil filter bowl. With no module available; they were hesitant to damage the filter bowl and concluded that the problem was indication only. The next flight; when the light came on again; the flight crew returned to the field. During the subsequent troubleshooting; the module was removed and the filter accessed; only to be found clean. However; when the chip detectors were checked; they contained material; leading to an engine change.

Narrative: Aircraft came in with a [logbook write-up] stating the left [engine] oil bypass light came on at landing. The crew who flew the plane in stated to the mechanics working the plane that the light flickered. Later that night the mechanics came to me and told me about the [logbook write-up] and the verbal from the crew. They stated they had inspected the Delta P (differential pressure switch) and it had not popped for the oil filter; they also tried to remove the filter bowl to replace the filter and it was stuck. I got into the IPC (Illustrated Parts Catalog) to see if we had the next higher component; the module that the filter bowl attaches to and we did not have one. In the meanwhile the mechanics went to the plane and cleaned the cannon plug and ran the engine and the bypass light did not re-illuminate. They came back in and told me about the situation and I dialed up Maintenance Control to tell them what was going on with the plane. I told Maintenance Control that the filter bowl was stuck and we would destroy it if we forced it any further plus we did not have the module 'next higher assembly'. Since we cleaned the plug; ran the engine and no delta P indication we; myself the Mechanic and the Controller; felt it was an indication issue; and we made the decision to clear the [logbook write-up]. I did not pull up the FIM (Fault Isolation Manual) that night and assumed that the mechanics did which I should have questioned when I reviewed the [logbook write-up] because of no mention of a FIM or MM (Maintenance Manual) used to come to this conclusion. The plane left the next morning and while on climbout at 25;000 FT the light came on and the plane returned to the field. Once back day shift removed the module and cut the filter bowl off and the filter was clean. They then looked at the chips [detectors] and found the gearbox detector had debris and the engine was changed.

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.