As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING FLIGHT, THE FLIGHT ATTENDANT NOTICED A LOUD HUMMING SOUND ACCOMPANIED BY VIBRATION. THIS COULD BE HEARD AND FELT NEAR THE REAR OF THE CABIN IN THE CABIN FLOOR. THE SOUND AND VIBRATION WAS ACCOMPANIED BY AN OILY/ ELECTRICAL SMELL IN THE COCKPIT. AFTER LANDING, THE AIR CYCLE MACHINE WAS FOUND TO BE SEIZED AND LEAKING OIL.