As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR721, AFTER TAKEOFF HAD DUAL RA FAILURE WITH TAIL STRIKE PROT FAIL MESSAGE ON EICAS. ADDITIONALLY RA FLAGS WERE DISPLAYED ON THE PFD'S. LANDING GEAR AURAL WARNING WENT OFF CONTINUOUSLY AND COULD NOT BE SILENCED BY LANDING GEAR EXTENSION. RETURNED TO DEPARTURE. PERFORMED FIM TASK 27-03-00-810-897-A, NO CORRELATED FAULTS FOUND. PERFORMED OPS TEST OF RADAR ALTIMETER UNIT NR1 IAW AMM 34-31-01. RADAR ALTIMETER NR1 WOULD NOT REAPPEAR ON CAPT PFD. REMOVED AND REPLACED RADAR ALTIMETER NR1 IAW AMM 34-31-01. OPS CHK OK. A/C FOR SVC.