As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA - FLT 991 - EN ROUTE MIA-EZE, DETECTED LOUD SQUEAL AT LEFT SIDE WINDSHIELD. SQUEAL INTERFERRED WITH COCKPIT COMMUNICATION AND RADIO COMMUNICATION WITH AIR TRAFFIC CONTROLLER. DUMPED APPROXIMTELY 80,000 LBS OF FUEL. RETURNED MIA AND LANDED WITHOUT FURTHER INCIDENT. REPLACED LEFT SIDE WINDOW SEAL. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)