Narrative:

I am currently employed as an a&P mechanic with the airline at the maintenance operation center. On dec/thu/92 I was sent to lax to do a job. I was working on a widebody transport #3 engine. The job consisted of removing a rosan fitting from the vent tube location on the transfer gearbox. I then had to drill and tap the hole to install a large threaded bushing. To minimize the threat of FOD entering the gearbox cavity I used a piece of a shop rag and petrolatum grease to block the back of the hole. After the tapping operation I realized that the rag may have fallen inside. Myself and a line mechanic from lax tried to find the rag, with no luck. We drained the gearbox and still did not find a rag. I notified the grave shift foreman at lax that I may have dropped a piece of a shop rag into the gearbox cavity. He sent another mechanic out to borescope the inside of the gearbox looking for a rag. The mechanic and the foreman inspected the inside of the gearbox and could not find anything. The foreman asked me repeatedly if I thought the rag was inside. I said I think it is. The rear cover was also pulled off the gearbox but we still could not see anything. At this point the foreman told me that as a result of borescoping the gearbox he did not believe the rag was inside. I was told to finish installing the bushing. Upon completion of the job I asked if I should stay for the leak check. The foreman said no, that it would be done later. I signed for installing the bushing and was taken to a hotel. Later that day I returned to sfo. Upon returning I was told the plane had flown and had to return to lax. I told local management what had happened. The engine was removed and sent to sfo maintenance operation center for repair. I was asked by local management to write a written statement because there would be an investigation by the airline quality assurance and a report submitted to the FAA. The rag was found and it had clogged the scavenge pump filter screen. I was interviewed twice by the airline quality assurance and they wrote a report that was submitted to the FAA. Throughout the course of the investigation I learned that the plane had flown for approximately 30 mins when the pilots had to shut down the #3 engine and return to lax. The problem I was told was a low oil pressure warning. The airline is currently working with quality assurance, engineering and mechanics to insure that this does not happen again.

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Original NASA ASRS Text

Title: COMPANY MECH USES A RAG TO BLOCK AN OPEN GEARBOX FROM FOD. RAG DISAPPEARS. SEARCH ENSUES, UNABLE TO LOCATE. ACFT DEPARTS AND MUST RETURN LAND DUE LOW OIL PRESSURE WARNING.

Narrative: I AM CURRENTLY EMPLOYED AS AN A&P MECH WITH THE AIRLINE AT THE MAINT OP CTR. ON DEC/THU/92 I WAS SENT TO LAX TO DO A JOB. I WAS WORKING ON A WDB #3 ENG. THE JOB CONSISTED OF REMOVING A ROSAN FITTING FROM THE VENT TUBE LOCATION ON THE TRANSFER GEARBOX. I THEN HAD TO DRILL AND TAP THE HOLE TO INSTALL A LARGE THREADED BUSHING. TO MINIMIZE THE THREAT OF FOD ENTERING THE GEARBOX CAVITY I USED A PIECE OF A SHOP RAG AND PETROLATUM GREASE TO BLOCK THE BACK OF THE HOLE. AFTER THE TAPPING OP I REALIZED THAT THE RAG MAY HAVE FALLEN INSIDE. MYSELF AND A LINE MECH FROM LAX TRIED TO FIND THE RAG, WITH NO LUCK. WE DRAINED THE GEARBOX AND STILL DID NOT FIND A RAG. I NOTIFIED THE GRAVE SHIFT FOREMAN AT LAX THAT I MAY HAVE DROPPED A PIECE OF A SHOP RAG INTO THE GEARBOX CAVITY. HE SENT ANOTHER MECH OUT TO BORESCOPE THE INSIDE OF THE GEARBOX LOOKING FOR A RAG. THE MECH AND THE FOREMAN INSPECTED THE INSIDE OF THE GEARBOX AND COULD NOT FIND ANYTHING. THE FOREMAN ASKED ME REPEATEDLY IF I THOUGHT THE RAG WAS INSIDE. I SAID I THINK IT IS. THE REAR COVER WAS ALSO PULLED OFF THE GEARBOX BUT WE STILL COULD NOT SEE ANYTHING. AT THIS POINT THE FOREMAN TOLD ME THAT AS A RESULT OF BORESCOPING THE GEARBOX HE DID NOT BELIEVE THE RAG WAS INSIDE. I WAS TOLD TO FINISH INSTALLING THE BUSHING. UPON COMPLETION OF THE JOB I ASKED IF I SHOULD STAY FOR THE LEAK CHK. THE FOREMAN SAID NO, THAT IT WOULD BE DONE LATER. I SIGNED FOR INSTALLING THE BUSHING AND WAS TAKEN TO A HOTEL. LATER THAT DAY I RETURNED TO SFO. UPON RETURNING I WAS TOLD THE PLANE HAD FLOWN AND HAD TO RETURN TO LAX. I TOLD LCL MGMNT WHAT HAD HAPPENED. THE ENG WAS REMOVED AND SENT TO SFO MAINT OP CTR FOR REPAIR. I WAS ASKED BY LCL MGMNT TO WRITE A WRITTEN STATEMENT BECAUSE THERE WOULD BE AN INVESTIGATION BY THE AIRLINE QUALITY ASSURANCE AND A RPT SUBMITTED TO THE FAA. THE RAG WAS FOUND AND IT HAD CLOGGED THE SCAVENGE PUMP FILTER SCREEN. I WAS INTERVIEWED TWICE BY THE AIRLINE QUALITY ASSURANCE AND THEY WROTE A RPT THAT WAS SUBMITTED TO THE FAA. THROUGHOUT THE COURSE OF THE INVESTIGATION I LEARNED THAT THE PLANE HAD FLOWN FOR APPROX 30 MINS WHEN THE PLTS HAD TO SHUT DOWN THE #3 ENG AND RETURN TO LAX. THE PROB I WAS TOLD WAS A LOW OIL PRESSURE WARNING. THE AIRLINE IS CURRENTLY WORKING WITH QUALITY ASSURANCE, ENGINEERING AND MECHS TO INSURE THAT THIS DOES NOT HAPPEN AGAIN.

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