What was found
AS THE POWER LEVERS WERE ADVANCED FOR TAKE OFF, WARNING HORN SOUNDED. ABORTED THE TAKE OFF AND RAN CHECKLISTS. DURING THE TAKE OFF WARNING TEST ON THE GROUND THE WARNING HORN DID NOT SOUND. R & R ELEVATOR TRIM INDICATOR IAW AMM 27-32-16-000-801 AND 27-32-16-400-801. OPS TEST OF ELEVATOR PITCH TRIM SYS IAW AMM 27-32-00-710-802 AND TESTED GOOD. FUNCTIONAL TEST OF THE TAKE OFF WARNING SYS IAW AMM 31-52-00-720-801, AND TESTED GOOD. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.