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A B737-200 was dispatched in non compliance with the standby airspeed indicator inoperative and deferred in conflict with the MEL.
| Attributes | |
| ACN | 457995 |
| Time | |
| Date | 199912 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : preflight ground : parked |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | oversight : supervisor |
| Qualification | technician : airframe technician : powerplant |
| Experience | maintenance supervisor : 2 maintenance technician : 10 |
| ASRS Report | 457995 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : powerplant technician : airframe |
| Experience | maintenance technician : 12 |
| ASRS Report | 457996 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : non compliance with mel non adherence : far non adherence : published procedure |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : weather contributing factor : schedule pressure contributing factor : manuals performance deficiency : fault isolation performance deficiency : non compliance with legal requirements performance deficiency : repair |
| Supplementary | |
| Problem Areas | Aircraft Chart Or Publication Maintenance Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
On dec/xa/99, I received a call from a ZZZ mechanic. He told me that the airspeed indicator on the standby altimeter was inoperative but the altimeter worked normal. He asked me if he could defer the airspeed indication. I looked at the MEL and found an item for 'true airspeed indication'. True airspeed uses raw data (pitot static) to produce an airspeed indication. The airspeed indication on the standby altimeter also uses raw data, which is why I made the association. The mechanic and I decided that this would be a legal MEL to use. On the first flight out of VVV on dec/wed/99 the flight crew questioned the MEL used and it was agreed that the MEL was incorrect. When I was notified of my error by my peers, I made a full disclosure to my supervisor abc wxx air carrier. FAA liaison yyw xyz and the local FAA representative B737. I made an error due to the fact that I was thinking about true airspeed indication only and I overlooked the fact that it was a standby indication of airspeed.
Original NASA ASRS Text
Title: A B737-200 WAS DISPATCHED IN NON COMPLIANCE WITH THE STANDBY AIRSPD INDICATOR INOP AND DEFERRED IN CONFLICT WITH THE MEL.
Narrative: ON DEC/XA/99, I RECEIVED A CALL FROM A ZZZ MECH. HE TOLD ME THAT THE AIRSPD INDICATOR ON THE STANDBY ALTIMETER WAS INOP BUT THE ALTIMETER WORKED NORMAL. HE ASKED ME IF HE COULD DEFER THE AIRSPD INDICATION. I LOOKED AT THE MEL AND FOUND AN ITEM FOR 'TRUE AIRSPD INDICATION'. TRUE AIRSPD USES RAW DATA (PITOT STATIC) TO PRODUCE AN AIRSPD INDICATION. THE AIRSPD INDICATION ON THE STANDBY ALTIMETER ALSO USES RAW DATA, WHICH IS WHY I MADE THE ASSOCIATION. THE MECH AND I DECIDED THAT THIS WOULD BE A LEGAL MEL TO USE. ON THE FIRST FLT OUT OF VVV ON DEC/WED/99 THE FLC QUESTIONED THE MEL USED AND IT WAS AGREED THAT THE MEL WAS INCORRECT. WHEN I WAS NOTIFIED OF MY ERROR BY MY PEERS, I MADE A FULL DISCLOSURE TO MY SUPVR ABC WXX ACR. FAA LIAISON YYW XYZ AND THE LCL FAA REPRESENTATIVE B737. I MADE AN ERROR DUE TO THE FACT THAT I WAS THINKING ABOUT TRUE AIRSPD INDICATION ONLY AND I OVERLOOKED THE FACT THAT IT WAS A STANDBY INDICATION OF AIRSPD.
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.