After measuring; evaluating and deferring a dent on the right aft fuselage behind the cargo door of a B737-300; a Mechanic dispatches the aircraft. A downline Lead Mechanic informs him that another dent in an adjacent section required aircraft be repaired per the Structural Repair Manual.

Narrative

Maintenance was called to look at a dent located on the right aft fuselage behind the cargo door of aircraft. I discovered after reviewing Maintenance records and where the dent was located that it was a new discovery. After taking measurements of the dent at approximately STA we went to the Structural Repair Manual to see if it was within limits. After making the calculations the dent was found to be within limits and a logbook entry was made and deferred. After dispatching the aircraft; I contacted Maintenance Control to have someone evaluate the dent to double-check my calculations. I have not had much experience using the Structural Repair Manual and wanted someone to check and make sure my calculations were correct and they said no problem. At approximately XA30; a Lead Technician calls and said the aircraft was being taken out of service. He took the time to explain the calculations were correct and the dent itself was within limits but the Structural Repair Manual allowable damage note 'v' (dents in 2 adjacent bays are not permitted). I was not aware the damage was to the extent that this note made it out of limits. After reviewing the Structural Repair Manual; it has made me more aware to take a closer look and pay particular attention to make certain that not only are the measurements critical but where the damage is located and does not extend into 2 adjacent bays as called out by the footnote. Have not had a lot of experience using the Structural Repair Manual and didn't notice the dent extending into 2 adjacent bays.