|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Locale Reference||airport : zzz.airport|
|Altitude||agl single value : 0|
|Controlling Facilities||tower : cpr.tower|
|Operator||common carrier : air carrier|
|Make Model Name||B737-700|
|Operating Under FAR Part||Part 125|
|Function||maintenance : technician|
|Qualification||technician : airframe|
technician : powerplant
|Affiliation||company : air carrier|
|Function||oversight : supervisor|
|Anomaly||aircraft equipment problem : critical|
maintenance problem : improper maintenance
non adherence : far
non adherence : published procedure
|Independent Detector||other other : 2|
|Resolutory Action||none taken : detected after the fact|
|Maintenance||contributing factor : manuals|
contributing factor : briefing
performance deficiency : non compliance with legal requirements
performance deficiency : training
performance deficiency : logbook entry
Maintenance Human Performance
|Primary Problem||Maintenance Human Performance|
During troubleshooting of speed brake; do not arm light; several maintenance actions were being performed to isolate maintenance problem. Per the fim troubleshooting steps; the stall management yaw damper #1 and stall management yaw damper #2 were swapped; therefore; downgrading aircraft from CAT III to CAT I status because of removing stall management yaw damper #1 computer. I was not aware that stall management yaw damper #1 was CAT III sensitive; so aircraft was never recertified. I discovered this the following day when I was troubleshooting another aircraft with same problem and the technical foreman reminded me to recertify aircraft if I remove stall management yaw damper #1 computer. To prevent in future; explore possibility of placarding CAT III sensitive components.
Original NASA ASRS Text
Title: A LINE MECHANIC SWAPS THE #1 STALL MANAGEMENT YAW DAMPER (SMYD) COMPUTER WITH SYMD #2; PER THE FAULT ISOLATION MANUAL (FIM) TROUBLESHOOTING PROCEDURES; BUT DOES NOT DOWNGRADE THE B737-700 TO A CAT-1 STATUS.
Narrative: DURING TROUBLESHOOTING OF SPD BRAKE; DO NOT ARM LIGHT; SEVERAL MAINT ACTIONS WERE BEING PERFORMED TO ISOLATE MAINT PROB. PER THE FIM TROUBLESHOOTING STEPS; THE STALL MGMNT YAW DAMPER #1 AND STALL MGMNT YAW DAMPER #2 WERE SWAPPED; THEREFORE; DOWNGRADING ACFT FROM CAT III TO CAT I STATUS BECAUSE OF REMOVING STALL MGMNT YAW DAMPER #1 COMPUTER. I WAS NOT AWARE THAT STALL MGMNT YAW DAMPER #1 WAS CAT III SENSITIVE; SO ACFT WAS NEVER RECERTIFIED. I DISCOVERED THIS THE FOLLOWING DAY WHEN I WAS TROUBLESHOOTING ANOTHER ACFT WITH SAME PROB AND THE TECHNICAL FOREMAN REMINDED ME TO RECERTIFY ACFT IF I REMOVE STALL MGMNT YAW DAMPER #1 COMPUTER. TO PREVENT IN FUTURE; EXPLORE POSSIBILITY OF PLACARDING CAT III SENSITIVE COMPONENTS.
Data retrieved from NASA's ASRS site as of May 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.