ACR MDT PIC PERFORMS 2 TKOFS ABORTED ACCOUNT TKOF WARNING HORN RELATED TO ACFT CONFIGN.

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AFTER COMPLETING THE RWY CHKS AND TAXIING ONTO THE RWY WE WERE CLRED FOR TKOF. AT ABOUT 40 PERCENT TORQUE; WE GOT A TKOF WARNING HORN; SO I; AS THE PF; ABORTED. WE CLRED THE RWY AND CHKED THE 6 ITEMS THAT CAUSE THE HORN TO SOUND. ALL ITEMS CHKED IN THE PROPER POS; SO WE WERE CLRED ONTO THE RWY AGAIN (POS AND HOLD). WE RECHKED ALL 6 ITEMS AGAIN; IN ADDITION TO THE RWY CHKS AND EVERYTHING WAS IN THE PROPER POS. WE WERE CLRED FOR TKOF AND AT 40 PERCENT TORQUE WE AGAIN GOT THE TKOF WARNING HORN. AFTER CLRING THE RWY AGAIN; I REMEMBERED A MEMO PUT OUT BY THE COMPANY IN 1990 THAT ADDRESSED ABNORMALITIES WITH THE TKOF WARNING HORN. I CONSULTED IT AND FOLLOWED THE PROC FOR SELECTING FLAPS TO 15 DEGS THEN BACK TO THE NORMAL 5 DEG POS. THE PROC WORKED AND WE DID A NORMAL TKOF (NO HORN) AND THE REST OF THE FLT WAS UNEVENTFUL. IF THIS STARTS TO BE A RECURRING PROB; I THINK IT SHOULD BE A PROC ON THE FIRST FLT OF THE DAY TO SELECT FLAPS TO 15 DEGS THEN BACK TO 5 DEGS. (PUT INTO OUR ORIGINATING CHKLIST DONE PRIOR TO FIRST FLT OF THE DAY). THE TYPE OF EQUIP I FLY IS THE MDT.