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Mechanic describes how he inadvertently installed the air sense safety sensor bolt heads in the wrong direction; causing an air turnback of a B737-300 aircraft.
| Attributes | |
| ACN | 813405 |
| Time | |
| Date | 200811 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Controlling Facilities | tower : sgj.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| ASRS Report | 813405 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper maintenance non adherence : far non adherence : published procedure |
| Independent Detector | other other : 1 |
| Resolutory Action | flight crew : diverted to another airport other |
| Consequence | other |
| Factors | |
| Maintenance | performance deficiency : scheduled maintenance performance deficiency : testing performance deficiency : non compliance with legal requirements performance deficiency : installation performance deficiency : inspection |
| Supplementary | |
| Problem Areas | Environmental Factor Maintenance Human Performance Aircraft |
| Primary Problem | Maintenance Human Performance |
Narrative:
I was assigned the job of replacing the air safety sensor on aircraft due to it being spliced into the wiring harness. When accomplishing this task; I pulled up the maintenance manual reference for the task. I read and understood that the mounting bolts were to be installed with the heads forward for the air safety sensor. While installing the sensor; I was standing on a ladder facing forward and I believe I inadvertently installed the bolts backwards thinking they were forward. Also; I removed the old sensor with the bolts facing the same way as I installed it. In between reading the maintenance manual and installing the safety sensor; I apparently installed the bolt backwards thinking they were installed correctly. I believe being in a cramped work area and being so focused on the task at hand I became disoriented as to whether the bolts were indeed facing forward.
Original NASA ASRS Text
Title: MECHANIC DESCRIBES HOW HE INADVERTENTLY INSTALLED THE AIR SENSE SAFETY SENSOR BOLT HEADS IN THE WRONG DIRECTION; CAUSING AN AIR TURNBACK OF A B737-300 AIRCRAFT.
Narrative: I WAS ASSIGNED THE JOB OF REPLACING THE AIR SAFETY SENSOR ON ACFT DUE TO IT BEING SPLICED INTO THE WIRING HARNESS. WHEN ACCOMPLISHING THIS TASK; I PULLED UP THE MAINT MANUAL REF FOR THE TASK. I READ AND UNDERSTOOD THAT THE MOUNTING BOLTS WERE TO BE INSTALLED WITH THE HEADS FORWARD FOR THE AIR SAFETY SENSOR. WHILE INSTALLING THE SENSOR; I WAS STANDING ON A LADDER FACING FORWARD AND I BELIEVE I INADVERTENTLY INSTALLED THE BOLTS BACKWARDS THINKING THEY WERE FORWARD. ALSO; I REMOVED THE OLD SENSOR WITH THE BOLTS FACING THE SAME WAY AS I INSTALLED IT. IN BTWN READING THE MAINT MANUAL AND INSTALLING THE SAFETY SENSOR; I APPARENTLY INSTALLED THE BOLT BACKWARDS THINKING THEY WERE INSTALLED CORRECTLY. I BELIEVE BEING IN A CRAMPED WORK AREA AND BEING SO FOCUSED ON THE TASK AT HAND I BECAME DISORIENTED AS TO WHETHER THE BOLTS WERE INDEED FACING FORWARD.
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.