As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE T/O ROLL AT APPROX 40 TO 60 KNOTS CAPT A/S INDICATOR REMAINED BLANK AND A/S COMPARISON MONITOR ILLUMINATED. T/O WAS ABORTED. VERIFIED DISCREPANCY. NOTED DIRT DEBRIS IN LT PITOT. PURGED PITOT LINE & TUBE WITH AIR. LEAK TEST CHECKS GOOD. AIRSPEED OPERATIONAL CHECKS GOOD. MAINTENANCE DONE IAW 560 MAINTENANCE MANUAL CH 34-11-05.