As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. ON TAKEOFF, LOUD NOISE DETECTED ON THE LEFT SIDE OF AIRPLANE, AFT OF THE COCKPIT. REMOVED AND REPLACED LEFT ENGINE CONSTANT SPEED DRIVE TRANSMISSION ASSEMBLY IAW AMM 24-10-01 AND THE AC GENERATOR IAW AMM 24-20-01 (AALA20170103018). OPERATIONAL CHECK GOOD.