Narrative:

#1 engine strut panel 5728L was removed on feb/fri/04 to work on #1 throttle tele-flex cable. 4 other mechanics assisted with various duties associated with the work on/with #1 throttle stiff. This panel was re-installed by another mechanic and I verified that it was in place. To my knowledge this panel installation was correct. What I believed caused panel 5728L to depart the aircraft was due to possible improper installation or a failed fastener. As I do not have the missing panel, I cannot speculate. I also think there are some mechanics who do not fully understand how these panel fasteners function.

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Original NASA ASRS Text

Title: A B737-500 HAD A L ENG PYLON PANEL DEPART THE ACFT DUE TO IMPROPER INSTALLATION AFTER MAINT.

Narrative: #1 ENG STRUT PANEL 5728L WAS REMOVED ON FEB/FRI/04 TO WORK ON #1 THROTTLE TELE-FLEX CABLE. 4 OTHER MECHS ASSISTED WITH VARIOUS DUTIES ASSOCIATED WITH THE WORK ON/WITH #1 THROTTLE STIFF. THIS PANEL WAS RE-INSTALLED BY ANOTHER MECH AND I VERIFIED THAT IT WAS IN PLACE. TO MY KNOWLEDGE THIS PANEL INSTALLATION WAS CORRECT. WHAT I BELIEVED CAUSED PANEL 5728L TO DEPART THE ACFT WAS DUE TO POSSIBLE IMPROPER INSTALLATION OR A FAILED FASTENER. AS I DO NOT HAVE THE MISSING PANEL, I CANNOT SPECULATE. I ALSO THINK THERE ARE SOME MECHS WHO DO NOT FULLY UNDERSTAND HOW THESE PANEL FASTENERS FUNCTION.

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.