As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB-OUT FROM ADDIS ABABA, ETHIOPIA (HAAB), AIRCRAFT PERFORMED AN AIR TURN BACK DUE TO INDICATION OF NR 4 ENGINE THRUST REVERSER TRYING TO DEPLOY IN FLIGHT. CREW WAS ALERTED BY THRUST REVERSER VALVE LIGHT AND TRANSIT LIGHT ILLUMINATING. CREW RETURNED TO HAAB WITH REVERSER PARTIALLY DEPLOYED. NO FUEL WAS DUMPED. MAINTENANCE TOOK ACTION TO LOCK OUT THRUST REVERSER AND SCHEDULE FOR APPROVED DEFERRED MAINTENANCE ACTION.