Narrative:

Returned to the gate for maintenance following an unsuccessful attempt to lower flaps for takeoff. During takeoff checklist; first officer noticed the amber leading edge flaps transit light illuminated with the flaps set for takeoff. The green leading edge flap light failed to illuminate even though the forward flap and the overhead annunciator panel for the leading edge flap devices indicated flaps/slats in proper position for selected position. The aircraft had the same write-up 2 days earlier and maintenance signed the gripe off after replacing the fseu control computer that appeared to fix the problem. At the gate with the flaps set for takeoff; the first officer and contract maintenance confirmed that the flaps/slats were symmetric and in the position selected. After troubleshooting the problem and in a 3-WAY conversation with dispatch; maintenance control and local contract maintenance personnel; the decision to placard the leading edge flap transit light inoperative was made and deferred per MEL 27-1A. After complying with the provisos of the MEL; we launched for the second time. When power was advanced for takeoff; the takeoff confign horn sounded and I immediately pulled the power to idle to doublechk our confign. Having conferred with the first officer and confirming that the proper confign was established except for the green leading edge flap extension not illuminated because of our placarded item; I elected to take off knowing that the horn would silence once we were airborne. En route after more careful deliberation with my first officer and the MEL; I felt that the MEL was ambiguous for the situation at hand and that we marched down the wrong decision matrix tree in solving the problem because the real issue might be a computer or sensor issue not covered by the MEL. I sent an ACARS message to dispatch requesting maintenance pull the aircraft OTS until they could determine the root cause of the improper lights. As luck would have it; the flight was uneventful with the flaps/slats working perfectly on landing. Furthermore; in an attempt to help maintenance troubleshoot the issue; the problem could not be duplicated on the ground while taxiing in with the lights working as advertised. In retrospect; I felt we conducted the flight safely; however; we indirectly may have followed the wrong path in rectifying the situation. Indirectly; I was trying to get our passenger safely to their destination while attempting to get the aircraft in a better location to fix the problem correctly.

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Original NASA ASRS Text

Title: A B737-800 WAS DISPATCHED WITH THE LEADING FLAP GREEN EXTEND INDICATION LIGHT DEFERRED. NOT ILLUMINATED WITH THE FLAPS AND SLATS EXTENDED.

Narrative: RETURNED TO THE GATE FOR MAINT FOLLOWING AN UNSUCCESSFUL ATTEMPT TO LOWER FLAPS FOR TKOF. DURING TKOF CHKLIST; FO NOTICED THE AMBER LEADING EDGE FLAPS TRANSIT LIGHT ILLUMINATED WITH THE FLAPS SET FOR TKOF. THE GREEN LEADING EDGE FLAP LIGHT FAILED TO ILLUMINATE EVEN THOUGH THE FORWARD FLAP AND THE OVERHEAD ANNUNCIATOR PANEL FOR THE LEADING EDGE FLAP DEVICES INDICATED FLAPS/SLATS IN PROPER POS FOR SELECTED POS. THE ACFT HAD THE SAME WRITE-UP 2 DAYS EARLIER AND MAINT SIGNED THE GRIPE OFF AFTER REPLACING THE FSEU CTL COMPUTER THAT APPEARED TO FIX THE PROB. AT THE GATE WITH THE FLAPS SET FOR TKOF; THE FO AND CONTRACT MAINT CONFIRMED THAT THE FLAPS/SLATS WERE SYMMETRIC AND IN THE POS SELECTED. AFTER TROUBLESHOOTING THE PROB AND IN A 3-WAY CONVERSATION WITH DISPATCH; MAINT CTL AND LCL CONTRACT MAINT PERSONNEL; THE DECISION TO PLACARD THE LEADING EDGE FLAP TRANSIT LIGHT INOP WAS MADE AND DEFERRED PER MEL 27-1A. AFTER COMPLYING WITH THE PROVISOS OF THE MEL; WE LAUNCHED FOR THE SECOND TIME. WHEN PWR WAS ADVANCED FOR TKOF; THE TKOF CONFIGN HORN SOUNDED AND I IMMEDIATELY PULLED THE PWR TO IDLE TO DOUBLECHK OUR CONFIGN. HAVING CONFERRED WITH THE FO AND CONFIRMING THAT THE PROPER CONFIGN WAS ESTABLISHED EXCEPT FOR THE GREEN LEADING EDGE FLAP EXTENSION NOT ILLUMINATED BECAUSE OF OUR PLACARDED ITEM; I ELECTED TO TAKE OFF KNOWING THAT THE HORN WOULD SILENCE ONCE WE WERE AIRBORNE. ENRTE AFTER MORE CAREFUL DELIBERATION WITH MY FO AND THE MEL; I FELT THAT THE MEL WAS AMBIGUOUS FOR THE SITUATION AT HAND AND THAT WE MARCHED DOWN THE WRONG DECISION MATRIX TREE IN SOLVING THE PROB BECAUSE THE REAL ISSUE MIGHT BE A COMPUTER OR SENSOR ISSUE NOT COVERED BY THE MEL. I SENT AN ACARS MESSAGE TO DISPATCH REQUESTING MAINT PULL THE ACFT OTS UNTIL THEY COULD DETERMINE THE ROOT CAUSE OF THE IMPROPER LIGHTS. AS LUCK WOULD HAVE IT; THE FLT WAS UNEVENTFUL WITH THE FLAPS/SLATS WORKING PERFECTLY ON LNDG. FURTHERMORE; IN AN ATTEMPT TO HELP MAINT TROUBLESHOOT THE ISSUE; THE PROB COULD NOT BE DUPLICATED ON THE GND WHILE TAXIING IN WITH THE LIGHTS WORKING AS ADVERTISED. IN RETROSPECT; I FELT WE CONDUCTED THE FLT SAFELY; HOWEVER; WE INDIRECTLY MAY HAVE FOLLOWED THE WRONG PATH IN RECTIFYING THE SITUATION. INDIRECTLY; I WAS TRYING TO GET OUR PAX SAFELY TO THEIR DEST WHILE ATTEMPTING TO GET THE ACFT IN A BETTER LOCATION TO FIX THE PROB CORRECTLY.

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.