Narrative:

During this day we had a main and scavenge oil filter impending bypass indicator activated. We did follow the P&west 72-01-50 manual and at one point with the scavenge filter we found a step that required a lab analysis; then I asked for the materials and tools and we did not have them in stock. The manual requires the lab analysis results in order to determine if the engine should be returned to service or may need other maintenance actions. See pratt & whitney canada 72-00-01 fault isolation figure 126 rgb scavenge oil filter impending bypass indicator activated. I did not find on this chart; nor at the 72-01-50 oil system -- inspection/check; an approval data to release the engine without the results. I was told by maintenance supervisor #1 and maintenance supervisor #2 that the aircraft was good to fly and that it did not require any other maintenance action other than filters replacement. They said that it should be carbon deposits and that it was not a concern. I told them that how we were going to track this condition until the lab analysis results were available; being this the normal procedure on other situations where lab results are sent out and waiting for results. If the debris is allowable; clean and install filters; strainer; chip detector strainer(south) and chip detectors. Record category; type and origin of debris. Send debris to an approved lab. The engine can be returned to service; pending the results of the lab analyzed debris. I couldn't find a reference like this one for the filters and I think that the manual is inconclusive. Maintenance supervisor #1 called pratt & whitney canada and we had a conversation with one of the representatives and he said that the engine should be checked regularly until the lab results were available; but no data was given in writing. This event occurred since the pratt & whitney canada manual was inconclusive! I think that the manual should be revised and/or the company should get some data with the help of the engine manufacturer in order to clarify this step. I think that management should stop pushing us to release something that is inconclusive. We had a huge engine failure during flight due to carbon deposits!

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Original NASA ASRS Text

Title: A LEAD MECHANIC EXPRESSES CONCERN ABOUT RELEASING ONE OF THEIR ATR-72 ACFT DUE TO ENG MAIN AND SCAVENGE OIL FILTER IMPENDING BYPASS INDICATOR BUTTON HAD POPPED (ACTIVATED) AND THE MAINT MANUAL SEEMED INCONCLUSIVE ABOUT WAITING FOR THE TEST RESULTS.

Narrative: DURING THIS DAY WE HAD A MAIN AND SCAVENGE OIL FILTER IMPENDING BYPASS INDICATOR ACTIVATED. WE DID FOLLOW THE P&W 72-01-50 MANUAL AND AT ONE POINT WITH THE SCAVENGE FILTER WE FOUND A STEP THAT REQUIRED A LAB ANALYSIS; THEN I ASKED FOR THE MATERIALS AND TOOLS AND WE DID NOT HAVE THEM IN STOCK. THE MANUAL REQUIRES THE LAB ANALYSIS RESULTS IN ORDER TO DETERMINE IF THE ENG SHOULD BE RETURNED TO SVC OR MAY NEED OTHER MAINT ACTIONS. SEE PRATT & WHITNEY CANADA 72-00-01 FAULT ISOLATION FIGURE 126 RGB SCAVENGE OIL FILTER IMPENDING BYPASS INDICATOR ACTIVATED. I DID NOT FIND ON THIS CHART; NOR AT THE 72-01-50 OIL SYSTEM -- INSPECTION/CHK; AN APPROVAL DATA TO RELEASE THE ENG WITHOUT THE RESULTS. I WAS TOLD BY MAINT SUPVR #1 AND MAINT SUPVR #2 THAT THE ACFT WAS GOOD TO FLY AND THAT IT DID NOT REQUIRE ANY OTHER MAINT ACTION OTHER THAN FILTERS REPLACEMENT. THEY SAID THAT IT SHOULD BE CARBON DEPOSITS AND THAT IT WAS NOT A CONCERN. I TOLD THEM THAT HOW WE WERE GOING TO TRACK THIS CONDITION UNTIL THE LAB ANALYSIS RESULTS WERE AVAILABLE; BEING THIS THE NORMAL PROC ON OTHER SITUATIONS WHERE LAB RESULTS ARE SENT OUT AND WAITING FOR RESULTS. IF THE DEBRIS IS ALLOWABLE; CLEAN AND INSTALL FILTERS; STRAINER; CHIP DETECTOR STRAINER(S) AND CHIP DETECTORS. RECORD CATEGORY; TYPE AND ORIGIN OF DEBRIS. SEND DEBRIS TO AN APPROVED LAB. THE ENG CAN BE RETURNED TO SVC; PENDING THE RESULTS OF THE LAB ANALYZED DEBRIS. I COULDN'T FIND A REF LIKE THIS ONE FOR THE FILTERS AND I THINK THAT THE MANUAL IS INCONCLUSIVE. MAINT SUPVR #1 CALLED PRATT & WHITNEY CANADA AND WE HAD A CONVERSATION WITH ONE OF THE REPRESENTATIVES AND HE SAID THAT THE ENG SHOULD BE CHKED REGULARLY UNTIL THE LAB RESULTS WERE AVAILABLE; BUT NO DATA WAS GIVEN IN WRITING. THIS EVENT OCCURRED SINCE THE PRATT & WHITNEY CANADA MANUAL WAS INCONCLUSIVE! I THINK THAT THE MANUAL SHOULD BE REVISED AND/OR THE COMPANY SHOULD GET SOME DATA WITH THE HELP OF THE ENG MANUFACTURER IN ORDER TO CLARIFY THIS STEP. I THINK THAT MGMNT SHOULD STOP PUSHING US TO RELEASE SOMETHING THAT IS INCONCLUSIVE. WE HAD A HUGE ENG FAILURE DURING FLT DUE TO CARBON DEPOSITS!

Data retrieved from NASA's ASRS site as of May 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.