Narrative:

I was called in on an MD88 that had experienced an air turn back for smoke in the cabin. After I arrived at work, I was informed that the APU had been found to be leaking oil from the join between the oil tank and the gear box. The on-shift technicians told me that the APU analyst had assisted in isolating the leak which was seen dripping from the oil tank just aft of the door actuator both while the APU was running or shutdown. My job was to lead a crew in a duct burnout. Two outstation technicians came in to do the burnout and my foreman told me that they had taken the paperwork upstairs while they had a meal before starting work. Since none of us had ever done this job before, we used the paperwork religiously in the complicated procedure. Also, while the technicians worked, I investigated the APU. Inspection revealed a heavily coked intake with active leaks along the left side and dripping from the drain mats forward of the intake. I disabled the APU and drained it of oil. The engine run was completed and I went into the office to work on paperwork. It was then that I discovered the open job card cabin smoke troubleshooting procedure paperwork. It was across the room from the lead's desk. When I discussed it with my foreman the next day, he remembered that the out of town technicians had separated the 2 paperworks when they went to eat. In any case, after reading it, I realized I had more work to complete in order to comply with this operation job card. Except for the engine inspection, I completed the extra work and made a determination on the previous engine run covered the open job card run requirement. We had run each engine/pack at part and high power settings over an extended period of time with no direct evidence of smoke in the cabin. In fact, I sent a technician back through the cabin repeatedly to check for smoke throughout the run-up. I was very satisfied that the APU had been the source of the smoke. Unfortunately, the aircraft experienced an air turn back the next day and an oil leak (internal) in the left engine was eventually found to be the culprit. The engine was subsequently replaced as was the APU and the aircraft was returned to service. Failure had occurred in communications affecting decision-making. If I had been informed of the additional operation to be completed, I would have started with the operation paperwork rather than the burnout procedure which is a step in the operation. I did it out of order as a result and didn't place my emphasis on troubleshooting so much as completion of the duct burnout and check out of each pack while pulling power. A simultaneous ongoing delay on a B757 may have added to the general confusion and breakdown of communication in the office. The coked up APU intake proved to be a red herring as well.

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Original NASA ASRS Text

Title: AN MD88 GNDED FOR SMOKE IN THE CABIN USED A TROUBLESHOOTING JOB CARD TO FIND THE FAULT. LEAD TECHNICIAN WORKED THE JOB CARD IN REVERSE ORDER AND MISSED AN ENG INTERNAL OIL LEAK CAUSING SMOKE IN THE CABIN.

Narrative: I WAS CALLED IN ON AN MD88 THAT HAD EXPERIENCED AN AIR TURN BACK FOR SMOKE IN THE CABIN. AFTER I ARRIVED AT WORK, I WAS INFORMED THAT THE APU HAD BEEN FOUND TO BE LEAKING OIL FROM THE JOIN BTWN THE OIL TANK AND THE GEAR BOX. THE ON-SHIFT TECHNICIANS TOLD ME THAT THE APU ANALYST HAD ASSISTED IN ISOLATING THE LEAK WHICH WAS SEEN DRIPPING FROM THE OIL TANK JUST AFT OF THE DOOR ACTUATOR BOTH WHILE THE APU WAS RUNNING OR SHUTDOWN. MY JOB WAS TO LEAD A CREW IN A DUCT BURNOUT. TWO OUTSTATION TECHNICIANS CAME IN TO DO THE BURNOUT AND MY FOREMAN TOLD ME THAT THEY HAD TAKEN THE PAPERWORK UPSTAIRS WHILE THEY HAD A MEAL BEFORE STARTING WORK. SINCE NONE OF US HAD EVER DONE THIS JOB BEFORE, WE USED THE PAPERWORK RELIGIOUSLY IN THE COMPLICATED PROC. ALSO, WHILE THE TECHNICIANS WORKED, I INVESTIGATED THE APU. INSPECTION REVEALED A HEAVILY COKED INTAKE WITH ACTIVE LEAKS ALONG THE L SIDE AND DRIPPING FROM THE DRAIN MATS FORWARD OF THE INTAKE. I DISABLED THE APU AND DRAINED IT OF OIL. THE ENG RUN WAS COMPLETED AND I WENT INTO THE OFFICE TO WORK ON PAPERWORK. IT WAS THEN THAT I DISCOVERED THE OPEN JOB CARD CABIN SMOKE TROUBLESHOOTING PROC PAPERWORK. IT WAS ACROSS THE ROOM FROM THE LEAD'S DESK. WHEN I DISCUSSED IT WITH MY FOREMAN THE NEXT DAY, HE REMEMBERED THAT THE OUT OF TOWN TECHNICIANS HAD SEPARATED THE 2 PAPERWORKS WHEN THEY WENT TO EAT. IN ANY CASE, AFTER READING IT, I REALIZED I HAD MORE WORK TO COMPLETE IN ORDER TO COMPLY WITH THIS OP JOB CARD. EXCEPT FOR THE ENG INSPECTION, I COMPLETED THE EXTRA WORK AND MADE A DETERMINATION ON THE PREVIOUS ENG RUN COVERED THE OPEN JOB CARD RUN REQUIREMENT. WE HAD RUN EACH ENG/PACK AT PART AND HIGH PWR SETTINGS OVER AN EXTENDED PERIOD OF TIME WITH NO DIRECT EVIDENCE OF SMOKE IN THE CABIN. IN FACT, I SENT A TECHNICIAN BACK THROUGH THE CABIN REPEATEDLY TO CHK FOR SMOKE THROUGHOUT THE RUN-UP. I WAS VERY SATISFIED THAT THE APU HAD BEEN THE SOURCE OF THE SMOKE. UNFORTUNATELY, THE ACFT EXPERIENCED AN AIR TURN BACK THE NEXT DAY AND AN OIL LEAK (INTERNAL) IN THE L ENG WAS EVENTUALLY FOUND TO BE THE CULPRIT. THE ENG WAS SUBSEQUENTLY REPLACED AS WAS THE APU AND THE ACFT WAS RETURNED TO SVC. FAILURE HAD OCCURRED IN COMS AFFECTING DECISION-MAKING. IF I HAD BEEN INFORMED OF THE ADDITIONAL OP TO BE COMPLETED, I WOULD HAVE STARTED WITH THE OP PAPERWORK RATHER THAN THE BURNOUT PROC WHICH IS A STEP IN THE OP. I DID IT OUT OF ORDER AS A RESULT AND DIDN'T PLACE MY EMPHASIS ON TROUBLESHOOTING SO MUCH AS COMPLETION OF THE DUCT BURNOUT AND CHK OUT OF EACH PACK WHILE PULLING PWR. A SIMULTANEOUS ONGOING DELAY ON A B757 MAY HAVE ADDED TO THE GENERAL CONFUSION AND BREAKDOWN OF COM IN THE OFFICE. THE COKED UP APU INTAKE PROVED TO BE A RED HERRING AS WELL.

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.