Narrative:

Upon applying takeoff power the takeoff warning horn sounded. The takeoff warning horn will sound only if any of these 3 conditions are not met. Trim not in green band, flaps or slats not in takeoff position, or speed brake not retracted. A quick scan showed all these conditions were met and the takeoff warning horn should not have sounded. Since we had just started our roll, the airspeed indicator had not even left the peg, we taxied off the runway to check it out. Found the speed brakes lever out of the detent slightly. Even though the speed brake armed light was not illuminated, the lever being slightly out of position caused the warning horn to sound. We checked the system out thoroughly and were satisfied the speed brake lever was the cause. We got back in line and continued our takeoff and flight. I don't know how this could have been prevented. All checklists were strictly performed. The speed brake lever was just not totally full forward but close enough not to cause the 'speed brake armed' light to illuminate. The actual speed brakes were not deployed nor would they have deployed. Conditions were safe and standard operating instruction were followed.

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Original NASA ASRS Text

Title: ACR MLG ABORTS TKOF AT EWR BECAUSE THE TKOF WARNING HORN SOUNDED UPON APPLICATION OF POWER. APPARENTLY, THE SPEED BRAKE LEVER WAS JUST FAR ENOUGH OUT OF THE DETENT THAT IT CAUSED THE WARNING HORN WITHOUT ILLUMINATING THE SPEED BRAKE ARMED LIGHT.

Narrative: UPON APPLYING TKOF PWR THE TKOF WARNING HORN SOUNDED. THE TKOF WARNING HORN WILL SOUND ONLY IF ANY OF THESE 3 CONDITIONS ARE NOT MET. TRIM NOT IN GREEN BAND, FLAPS OR SLATS NOT IN TKOF POS, OR SPD BRAKE NOT RETRACTED. A QUICK SCAN SHOWED ALL THESE CONDITIONS WERE MET AND THE TKOF WARNING HORN SHOULD NOT HAVE SOUNDED. SINCE WE HAD JUST STARTED OUR ROLL, THE AIRSPD INDICATOR HAD NOT EVEN LEFT THE PEG, WE TAXIED OFF THE RWY TO CHK IT OUT. FOUND THE SPD BRAKES LEVER OUT OF THE DETENT SLIGHTLY. EVEN THOUGH THE SPD BRAKE ARMED LIGHT WAS NOT ILLUMINATED, THE LEVER BEING SLIGHTLY OUT OF POS CAUSED THE WARNING HORN TO SOUND. WE CHKED THE SYS OUT THOROUGHLY AND WERE SATISFIED THE SPD BRAKE LEVER WAS THE CAUSE. WE GOT BACK IN LINE AND CONTINUED OUR TKOF AND FLT. I DON'T KNOW HOW THIS COULD HAVE BEEN PREVENTED. ALL CHKLISTS WERE STRICTLY PERFORMED. THE SPD BRAKE LEVER WAS JUST NOT TOTALLY FULL FORWARD BUT CLOSE ENOUGH NOT TO CAUSE THE 'SPD BRAKE ARMED' LIGHT TO ILLUMINATE. THE ACTUAL SPD BRAKES WERE NOT DEPLOYED NOR WOULD THEY HAVE DEPLOYED. CONDITIONS WERE SAFE AND STANDARD OPERATING INSTRUCTION WERE FOLLOWED.

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.