As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - FLT 78 - EN ROUTE LAX/PHL, CREW REPORTED THEY HAD AN AIRFRAME VIBRATION AND HEARD A LOUD BANGING ON THE FUSELAGE. FLIGHT DIVERTED TO DEN AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND THE LEFT HYDRAULIC SERVICE PANEL MISSING AND DAMAGE TO THE AIRCRAFT STRUCTURE AT STA 1240. SERVICE PANEL WAS REPLACED AND THE DAMAGE REPAIRED OR INSPECTED AND PROGRAMMED FOR REPAIR. (X)