As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON ROTATION THE RT TOP COWLING PANEL ON THE ENGINE OPENED AND BEGAN FLAPPING/BENT. CREW REQUESTED TO RETURN TO AIRPORT / REDUCED SPEED TO 160 KTS AND RETURNED WITHOUT INCIDENT. MX IS INSPECTING AND REPLACING PANEL. SWAPPED FWD COWLING OFF OF 309CE. STILL WAITING ON MORE INFO.