As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAKEOFF ROLL, DEPARTING FROM SJU, CREW NOTICED THAT THERE WAS NO AIRSPEED INDICATION FROM F/O INDICATOR. CAPTAIN INDICATOR SHOWING BETWEEN 75-80 KTS AND FLUCTUATING. ABORTED T/O PROCEDURES FOLLOWED. RETURNED TO GATE. MAINT FOUND PITOT LINES CLOGGED WITH VOLCANIC ASH. LINES BACK FLUSHED IAW 34-11-10/302 ALL LINES RECONNECTED WITH LOW RANGE LEAK TEST ACCOMPLISHED IAW 34-11-10/501-515 SYSTEM TEST NORMAL, NO LEAKS IN SYSTEM. AIRCRAFT RETURNED TO SERVICE.