Narrative:

I, abc wxxx airframe and pwrplant technician #wwxxzz, employed at air carrier as a&P technician, was working on oct/sun/99 as an inspector, inspecting both engines on B737-300 aircraft xyz. As we finished all routine and non routine tasks, aircraft was returned to service on the morning of oct/mon/99. As it left ZZZ airport, sometime during flight 3 each small access panels departed from #2 engine pylon for unknown reasons. I had done my inspection prior to aircraft being returned to service and verified all access panels to be installed and being present. At that time aircraft was turned over to oncoming inspector at XA30 where engine #1 and #2 vibration survey was successfully complied with. Aircraft then returned to hangar, then final walkaround was accomplished and verified all access and service panels to be secured. Aircraft then was operated on air carrier flight xzx from ZZZ airport to VVV, us. After arriving at VVV, flight crew reported that 3 access panels (4827R, 5828R, and 5829R) on top of right engine pylon were missing. Since access panels were secondary structure they were put on cdl per air carrier policies and aircraft continued in service and all 3 panels were replaced later on. No damage had occurred due to this incident.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED IN NON COMPLIANCE WITH THE R ENG PYLON UPPER SURFACE ACCESS PLATES NOT SECURED.

Narrative: I, ABC WXXX AIRFRAME AND PWRPLANT TECHNICIAN #WWXXZZ, EMPLOYED AT ACR AS A&P TECHNICIAN, WAS WORKING ON OCT/SUN/99 AS AN INSPECTOR, INSPECTING BOTH ENGS ON B737-300 ACFT XYZ. AS WE FINISHED ALL ROUTINE AND NON ROUTINE TASKS, ACFT WAS RETURNED TO SVC ON THE MORNING OF OCT/MON/99. AS IT LEFT ZZZ ARPT, SOMETIME DURING FLT 3 EACH SMALL ACCESS PANELS DEPARTED FROM #2 ENG PYLON FOR UNKNOWN REASONS. I HAD DONE MY INSPECTION PRIOR TO ACFT BEING RETURNED TO SVC AND VERIFIED ALL ACCESS PANELS TO BE INSTALLED AND BEING PRESENT. AT THAT TIME ACFT WAS TURNED OVER TO ONCOMING INSPECTOR AT XA30 WHERE ENG #1 AND #2 VIBRATION SURVEY WAS SUCCESSFULLY COMPLIED WITH. ACFT THEN RETURNED TO HANGAR, THEN FINAL WALKAROUND WAS ACCOMPLISHED AND VERIFIED ALL ACCESS AND SVC PANELS TO BE SECURED. ACFT THEN WAS OPERATED ON ACR FLT XZX FROM ZZZ ARPT TO VVV, US. AFTER ARRIVING AT VVV, FLC RPTED THAT 3 ACCESS PANELS (4827R, 5828R, AND 5829R) ON TOP OF R ENG PYLON WERE MISSING. SINCE ACCESS PANELS WERE SECONDARY STRUCTURE THEY WERE PUT ON CDL PER ACR POLICIES AND ACFT CONTINUED IN SVC AND ALL 3 PANELS WERE REPLACED LATER ON. NO DAMAGE HAD OCCURRED DUE TO THIS INCIDENT.

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.