Narrative:

Start up and taxi were normal until we reached the departure end of runway xl. I called for the before takeoff checklist in anticipation of being cleared for takeoff; and at about that same time; we were in fact cleared for takeoff. Before the first officer responded to ATC and accepted the clearance; I turned the APU off; resulting in a loss of electrical power. I immediately turned on both engine generators; restoring power. The first officer told tower we needed to hold short for just a moment and tower canceled our takeoff clearance. We had not moved across the hold short line. We checked all system and re-ran the before taxi and before takeoff checklists; discussed the situation; and were both comfortable that we could continue; having re-run the appropriate checklists. We contacted tower ready to depart and departure and remainder of flight was normal. The first officer and I discussed whether or not this was an abandoned takeoff; and since we had not accepted the clearance; we both feel it was not. However; we concur that filing an as soon as possible is warranted; in the event that tower reports it as an abandoned takeoff; and more importantly; to provide the data on a flow/checklist xchk error. I attribute this event to my not placing the engine generators on line after the ground crew was clear; per normal SOP and flows. I then did not confirm that the generators were on line during the before taxi checklist (which we did run per SOP); even though the blue lights were staring me in the face. Closer adherence to SOP; flows; and continued vigilance in xchks during checklists. Omission of a flow step; followed by missing it on the checklist.

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Original NASA ASRS Text

Title: A B737-300 CREW DID NOT COMPLETE THE AFTER START CHKLIST BEFORE TKOF WHEN THE APU WAS TURNED OFF. ELECTRICAL POWER WAS LOST BECAUSE THE ENG GENS WERE OFF.

Narrative: START UP AND TAXI WERE NORMAL UNTIL WE REACHED THE DEP END OF RWY XL. I CALLED FOR THE BEFORE TKOF CHKLIST IN ANTICIPATION OF BEING CLRED FOR TKOF; AND AT ABOUT THAT SAME TIME; WE WERE IN FACT CLRED FOR TKOF. BEFORE THE FO RESPONDED TO ATC AND ACCEPTED THE CLRNC; I TURNED THE APU OFF; RESULTING IN A LOSS OF ELECTRICAL PWR. I IMMEDIATELY TURNED ON BOTH ENG GENERATORS; RESTORING PWR. THE FO TOLD TWR WE NEEDED TO HOLD SHORT FOR JUST A MOMENT AND TWR CANCELED OUR TKOF CLRNC. WE HAD NOT MOVED ACROSS THE HOLD SHORT LINE. WE CHKED ALL SYS AND RE-RAN THE BEFORE TAXI AND BEFORE TKOF CHKLISTS; DISCUSSED THE SITUATION; AND WERE BOTH COMFORTABLE THAT WE COULD CONTINUE; HAVING RE-RUN THE APPROPRIATE CHKLISTS. WE CONTACTED TWR READY TO DEPART AND DEP AND REMAINDER OF FLT WAS NORMAL. THE FO AND I DISCUSSED WHETHER OR NOT THIS WAS AN ABANDONED TKOF; AND SINCE WE HAD NOT ACCEPTED THE CLRNC; WE BOTH FEEL IT WAS NOT. HOWEVER; WE CONCUR THAT FILING AN ASAP IS WARRANTED; IN THE EVENT THAT TWR RPTS IT AS AN ABANDONED TKOF; AND MORE IMPORTANTLY; TO PROVIDE THE DATA ON A FLOW/CHKLIST XCHK ERROR. I ATTRIBUTE THIS EVENT TO MY NOT PLACING THE ENG GENERATORS ON LINE AFTER THE GND CREW WAS CLR; PER NORMAL SOP AND FLOWS. I THEN DID NOT CONFIRM THAT THE GENERATORS WERE ON LINE DURING THE BEFORE TAXI CHKLIST (WHICH WE DID RUN PER SOP); EVEN THOUGH THE BLUE LIGHTS WERE STARING ME IN THE FACE. CLOSER ADHERENCE TO SOP; FLOWS; AND CONTINUED VIGILANCE IN XCHKS DURING CHKLISTS. OMISSION OF A FLOW STEP; FOLLOWED BY MISSING IT ON THE CHKLIST.

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.