<h1>Suspected aircraft tailpipe exhaust fire on ground prompts precautionary return and four-plus hour delay; inspections clear aircraft</h1> An aircraft bound for an international destination experienced a suspected tailpipe (exhaust) fire while at a domestic airport and returned to the bay; the flight was delayed by more than four hours. Crew reported no cockpit warnings or indications but elected to return as a precautionary safety measure. Detailed engineering inspections found no abnormalities and the aircraft was cleared to resume operations. Passenger counts were not immediately available. The incident involved a jet engine internal/tailpipe fire occurring on the ground, typically associated with engine start or shutdown phases.