As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT'S REPORTED VIBRATION IN RT ENGINE, ALSO STATED SOMETHING SEEMED LOOSE AND RATTLING. LEANED AT DIFFERENT POWER SETTINGS WHILE IN FLIGHT WITH NO CHANGES. RETURNED TO AIRPORT WITHOUT INCIDENT. UNCOWLED RT ENGINE AND FOUND NR 2 CYLINDER EXHAUST RISER BROKEN OFF AT MOUNT FLANGE. REPLACED WITH NEW RISER AND GASKET, OPERATIONAL CHECK GOOD.