As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE THE FLIGHT CREW NOTED LOSS OF PORT SYSTEMS, INDICATING A GEARBOX OUT CONDITION, ALTHOUGH NO ABNORMAL POWERPLANT VIBRATIONS WAS EXPERIENCED. THE AIRCRAFT RETURNED TO BASE AND LANDED WITHOUT INCIDENT UNDER NORMAL POWER. THE ACCESSORY GARBOX WAS REMOVED. IT APPEARS THE INTERNAL ATTACH STUDS SECURING THE TUNNEL SHAFT BACKED OFF. THE UNIT WILL BE FORWARDED TO AN OVERHAUL AGENCY FOR FURTHER INVESTIGATION.