 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
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.
| Attributes | |
| ACN | 809040 |
| Time | |
| Date | 200810 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Controlling Facilities | tower : cpr.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 125 |
| Person 1 | |
| Function | maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| ASRS Report | 809040 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | oversight : supervisor |
| Events | |
| 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 |
| Consequence | other |
| Factors | |
| Maintenance | contributing factor : manuals contributing factor : briefing performance deficiency : non compliance with legal requirements performance deficiency : training performance deficiency : logbook entry |
| Supplementary | |
| Problem Areas | Aircraft Maintenance Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
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.