Narrative:

While performing our taxi checklist in preparation for a flight from ewr to cmh, we discovered a warning light for the left alpha vane (angle of attack sensor). We got clearance and parked where we could check out the problem and proceeded to pull and reset any circuit breakers which we thought might be involved. Then we called our maintenance control on the radio and he offered some suggestions and we decided we should return to the gate. The alpha vane was broken. After further discussion with our maintenance control and an air carrier mechanic (in person), we deferred our left stall warning system and GPWS system, and proceeded to columbus. During the flight to cmh, we noticed other minor problems with the automatic flight system: the autothrottle system always commanded maximum continuous thrust and the autoslat system was inoperative. When we arrived in cmh and our mechanics met us, we were told that we had looked at and cited the wrong MEL paragraph. We used one from the stall warning chapter, which seemed logical, and we should have used one from the autoflt control chapter, which seemed obscure. The mechanics said an almost identical situation happened 2 weeks previous. We had the proper MEL deferrals signed off and proceeded to las, where repairs were made. In conclusion, we placed too much faith in the mechanics involved and did not thoroughly analyze the situation on our own. Our MEL document could have easily included a xref notation or a complete index, which would have avoided the situation entirely.

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Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED WITH THE L ANGLE OF ATTACK SENSOR BROKEN OFF AND DEFERRED IN CONFLICT WITH THE MEL REQUIREMENTS.

Narrative: WHILE PERFORMING OUR TAXI CHKLIST IN PREPARATION FOR A FLT FROM EWR TO CMH, WE DISCOVERED A WARNING LIGHT FOR THE L ALPHA VANE (ANGLE OF ATTACK SENSOR). WE GOT CLRNC AND PARKED WHERE WE COULD CHK OUT THE PROB AND PROCEEDED TO PULL AND RESET ANY CIRCUIT BREAKERS WHICH WE THOUGHT MIGHT BE INVOLVED. THEN WE CALLED OUR MAINT CTL ON THE RADIO AND HE OFFERED SOME SUGGESTIONS AND WE DECIDED WE SHOULD RETURN TO THE GATE. THE ALPHA VANE WAS BROKEN. AFTER FURTHER DISCUSSION WITH OUR MAINT CTL AND AN ACR MECH (IN PERSON), WE DEFERRED OUR L STALL WARNING SYS AND GPWS SYS, AND PROCEEDED TO COLUMBUS. DURING THE FLT TO CMH, WE NOTICED OTHER MINOR PROBS WITH THE AUTOMATIC FLT SYS: THE AUTOTHROTTLE SYS ALWAYS COMMANDED MAX CONTINUOUS THRUST AND THE AUTOSLAT SYS WAS INOP. WHEN WE ARRIVED IN CMH AND OUR MECHS MET US, WE WERE TOLD THAT WE HAD LOOKED AT AND CITED THE WRONG MEL PARAGRAPH. WE USED ONE FROM THE STALL WARNING CHAPTER, WHICH SEEMED LOGICAL, AND WE SHOULD HAVE USED ONE FROM THE AUTOFLT CTL CHAPTER, WHICH SEEMED OBSCURE. THE MECHS SAID AN ALMOST IDENTICAL SIT HAPPENED 2 WKS PREVIOUS. WE HAD THE PROPER MEL DEFERRALS SIGNED OFF AND PROCEEDED TO LAS, WHERE REPAIRS WERE MADE. IN CONCLUSION, WE PLACED TOO MUCH FAITH IN THE MECHS INVOLVED AND DID NOT THOROUGHLY ANALYZE THE SIT ON OUR OWN. OUR MEL DOCUMENT COULD HAVE EASILY INCLUDED A XREF NOTATION OR A COMPLETE INDEX, WHICH WOULD HAVE AVOIDED THE SIT ENTIRELY.

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.