Narrative:

I was assigned to aircraft X during its heavy maintenance visit. Yesterday I found out the panel 5725L was not reinstalled under the #1 engine thrust reverser 'C' duct and that I had stamped the accomplishment of that task on job card X. Panel 5725L is a 6 inch (approximately) panel located under the l-hand thrust reverser half on the pylon. The thrust reverser must be opened to gain access to the panel. This is the only panel requiring thrust reverser opening to remove. All other pylon access panels removed were placed in a group on the wing docking stand; which was located in front of the wing; as it is only used for airbus A330 aircraft. Access panel 5725L was placed on older shelves under the tail stand at the rear of the aircraft; possibly due to being removed separately due to the requirement of opening the thrust reverser half to remove the panel. The panels are grouped on the installation paperwork with 3-6 panels on single signoff blocks. The thrust reverser open/close paperwork does not refer to this job card being completed before closing the thrust reverser half. Upon receiving the panel installation job card; I installed the panels in groups as they are located on the pylon. As most were small inspection panels; I took a handful of the panels on the ladder; installed them and check-marked the panel numbers on the paperwork to keep track of the panels installed. On step 3A; I installed panel 5726L located above the thrust reverser; and check-marked it. I also installed the l-hand panels from step 3D on the side of the reverser and check-marked them. I then installed the remaining r-hand side panels on step 3D and stamped the completed block. Then the r-hand panels on step 3A were installed. Whether lunch; break; or other distrs; such as having to stop for a hydraulic/flap check played a part in the chain of events; I don't remember; but at this point there were no remaining panels where the pile was on the wing dock; and no visible access panel openings on the pylon; so it seems I went ahead and stamped the block. Not having actively performed maintenance on B737 aircraft for the last 9 yrs (spent in the composite/flight controls overhaul shop); the hidden panel under the thrust reverser 'C' duct did not make the immediate connection in my mind and raise an internal alarm as it would have then with current experience.

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Original NASA ASRS Text

Title: A B737-300 WAS RELEASED FROM HVY MAINT WITH AN INSPECTION CLOSEOUT PANEL ON THE PYLON MISSING.

Narrative: I WAS ASSIGNED TO ACFT X DURING ITS HVY MAINT VISIT. YESTERDAY I FOUND OUT THE PANEL 5725L WAS NOT REINSTALLED UNDER THE #1 ENG THRUST REVERSER 'C' DUCT AND THAT I HAD STAMPED THE ACCOMPLISHMENT OF THAT TASK ON JOB CARD X. PANEL 5725L IS A 6 INCH (APPROX) PANEL LOCATED UNDER THE L-HAND THRUST REVERSER HALF ON THE PYLON. THE THRUST REVERSER MUST BE OPENED TO GAIN ACCESS TO THE PANEL. THIS IS THE ONLY PANEL REQUIRING THRUST REVERSER OPENING TO REMOVE. ALL OTHER PYLON ACCESS PANELS REMOVED WERE PLACED IN A GROUP ON THE WING DOCKING STAND; WHICH WAS LOCATED IN FRONT OF THE WING; AS IT IS ONLY USED FOR AIRBUS A330 ACFT. ACCESS PANEL 5725L WAS PLACED ON OLDER SHELVES UNDER THE TAIL STAND AT THE REAR OF THE ACFT; POSSIBLY DUE TO BEING REMOVED SEPARATELY DUE TO THE REQUIREMENT OF OPENING THE THRUST REVERSER HALF TO REMOVE THE PANEL. THE PANELS ARE GROUPED ON THE INSTALLATION PAPERWORK WITH 3-6 PANELS ON SINGLE SIGNOFF BLOCKS. THE THRUST REVERSER OPEN/CLOSE PAPERWORK DOES NOT REFER TO THIS JOB CARD BEING COMPLETED BEFORE CLOSING THE THRUST REVERSER HALF. UPON RECEIVING THE PANEL INSTALLATION JOB CARD; I INSTALLED THE PANELS IN GROUPS AS THEY ARE LOCATED ON THE PYLON. AS MOST WERE SMALL INSPECTION PANELS; I TOOK A HANDFUL OF THE PANELS ON THE LADDER; INSTALLED THEM AND CHK-MARKED THE PANEL NUMBERS ON THE PAPERWORK TO KEEP TRACK OF THE PANELS INSTALLED. ON STEP 3A; I INSTALLED PANEL 5726L LOCATED ABOVE THE THRUST REVERSER; AND CHK-MARKED IT. I ALSO INSTALLED THE L-HAND PANELS FROM STEP 3D ON THE SIDE OF THE REVERSER AND CHK-MARKED THEM. I THEN INSTALLED THE REMAINING R-HAND SIDE PANELS ON STEP 3D AND STAMPED THE COMPLETED BLOCK. THEN THE R-HAND PANELS ON STEP 3A WERE INSTALLED. WHETHER LUNCH; BREAK; OR OTHER DISTRS; SUCH AS HAVING TO STOP FOR A HYD/FLAP CHK PLAYED A PART IN THE CHAIN OF EVENTS; I DON'T REMEMBER; BUT AT THIS POINT THERE WERE NO REMAINING PANELS WHERE THE PILE WAS ON THE WING DOCK; AND NO VISIBLE ACCESS PANEL OPENINGS ON THE PYLON; SO IT SEEMS I WENT AHEAD AND STAMPED THE BLOCK. NOT HAVING ACTIVELY PERFORMED MAINT ON B737 ACFT FOR THE LAST 9 YRS (SPENT IN THE COMPOSITE/FLT CTLS OVERHAUL SHOP); THE HIDDEN PANEL UNDER THE THRUST REVERSER 'C' DUCT DID NOT MAKE THE IMMEDIATE CONNECTION IN MY MIND AND RAISE AN INTERNAL ALARM AS IT WOULD HAVE THEN WITH CURRENT EXPERIENCE.

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