A Maintenance Controller reports he allowed a B737-800 to continue in service with a 'ding' in the cargo pit entry scuff plate. Aircraft later required maintenance and scheduled inspections for the damaged scuff plate.

Narrative

I received a call from who I believed was the Captain; presumably on his cell phone. He said something to the effect that he had Contract Mechanic there; who needed to talk to me. The phone was handed-off to the Contract Mechanic; who said that the item was not written up; but the Captain wanted to make sure that they were good to go. The Mechanic told me that there was a ding the size of half a thumbnail in a cargo door scuff plate. I looked at my nails and thought of my finger pressing into a piece of clay; and what size of a ding that would make. Since most of my recent experience is related to avionics; I put the phone on hold and asked all the controllers in the room at the time; if they thought that a thumbnail size ding would need to be written-up. We talked about this part being a scuff plate; with the intention to take abuse of cargo scraping its way into the pit; and all agreed that what was described did not need to be addressed with a write-up. I released the phone hold and told the Mechanic that; if that was on the scuff plate; it was not significant and we were good to go. I believed the ding to be an insignificant 'normal wear and tear' item. The airplane left with no additional communication. Upon arrival; the damage was found to need maintenance and scheduled inspections. In retrospect; I should have asked the crew to write up the item; had Mechanic forward pictures and evaluated the damage per the structural repair manual (SRM).