As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT DIVERTED TO LHR ON ACCOUNT OF APU FAULT AND RIGHT ENGINE GENERATOR ON PLACARD. EMERGENCY DECLARED. MAINTENANCE REPLACED RT IDG IAW AMM 24-11-01. OPS AND LEAK CHECK OK. CHECKED AND PERFORMED APU CONTROL UNIT BITE TEST IAW AMM 49-61-05 AND FOUND GEN FILTER FAULT. REMOVED AND REPLACED GENERATOR SCAVENGE FILTER IAW AMM 49-27-03. RAN APU AND FOUND OK. (SEE SDR # AALA201909179008)