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A B737-700 mechanic mistakenly disconnected the #1 engine nose cowl thermal anti-ice second officer valve connector instead of the tcai pressure switch connector. This was an MEL deferral procedure.
| Attributes | |
| ACN | 763944 |
| Time | |
| Date | 200711 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| Experience | maintenance technician : 10 |
| ASRS Report | 763944 |
| Events | |
| Anomaly | maintenance problem : improper maintenance maintenance problem : non compliance with mel non adherence : far non adherence : published procedure |
| Independent Detector | aircraft equipment other aircraft equipment : eng anti-ice indications |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other |
| Factors | |
| Maintenance | contributing factor : non availability of parts performance deficiency : non compliance with legal requirements performance deficiency : installation |
| Supplementary | |
| Problem Areas | Maintenance Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
Crew called off aircraft X and reported #1 engine cowl anti-ice valve light illuminated in-flight. Parts for fix were not in stock in ZZZ. Proceeded in performing MEL. I locked the high stage valve closed; locked the tcai valve open. I mistakenly disconnected the tcai valve electrical connector instead of the specified tcai pressure switch connector. The aircraft was returned to service and flew several legs before being written up in ZZZ1 for the same light. Contract maintenance was called in ZZZ1 and the correct connector was removed to prevent false flight deck indications from occurring again; before the permanent repair can be performed. In short MEL was deviated from; all valves were properly positioned; the wrong electrical connector in the system was removed allowing an erroneous indication to be seen. I have thoroughly reviewed MEL and fully understand the procedures.
Original NASA ASRS Text
Title: A B737-700 MECHANIC MISTAKENLY DISCONNECTED THE #1 ENG NOSE COWL THERMAL ANTI-ICE S/O VALVE CONNECTOR INSTEAD OF THE TCAI PRESSURE SWITCH CONNECTOR. THIS WAS AN MEL DEFERRAL PROCEDURE.
Narrative: CREW CALLED OFF ACFT X AND RPTED #1 ENG COWL ANTI-ICE VALVE LIGHT ILLUMINATED INFLT. PARTS FOR FIX WERE NOT IN STOCK IN ZZZ. PROCEEDED IN PERFORMING MEL. I LOCKED THE HIGH STAGE VALVE CLOSED; LOCKED THE TCAI VALVE OPEN. I MISTAKENLY DISCONNECTED THE TCAI VALVE ELECTRICAL CONNECTOR INSTEAD OF THE SPECIFIED TCAI PRESSURE SWITCH CONNECTOR. THE ACFT WAS RETURNED TO SVC AND FLEW SEVERAL LEGS BEFORE BEING WRITTEN UP IN ZZZ1 FOR THE SAME LIGHT. CONTRACT MAINT WAS CALLED IN ZZZ1 AND THE CORRECT CONNECTOR WAS REMOVED TO PREVENT FALSE FLT DECK INDICATIONS FROM OCCURRING AGAIN; BEFORE THE PERMANENT REPAIR CAN BE PERFORMED. IN SHORT MEL WAS DEVIATED FROM; ALL VALVES WERE PROPERLY POSITIONED; THE WRONG ELECTRICAL CONNECTOR IN THE SYS WAS REMOVED ALLOWING AN ERRONEOUS INDICATION TO BE SEEN. I HAVE THOROUGHLY REVIEWED MEL AND FULLY UNDERSTAND THE PROCS.
Data retrieved from NASA's ASRS site as of January 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.