B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Type 12000
Inflight Event / Encounter Bird / Animal
Aircraft Aircraft Damaged; General Flight Cancelled / Delayed; General Maintenance Action
Environment - Non Weather Related
Just before pushback one of our Ramp Agents came into the cockpit and showed me a picture of what he thought was a dent on the vertical stabilizer. I proceeded outside and checked to make sure there was a dent that I was looking at about three by two inches about 40 ft high (1.5 ft below the top of the vertical stabilizer). I called Dispatch and he passed me to Maintenance Control. I reported what was found. Maintenance Control informed me that there was a small dent already reported on that area. I told them this was not small and it looked like there was some damage to the aircraft. They told me to write it up and to call Contract Maintenance. Luckily we had two of our Mechanics at the Station. They came to the aircraft and were able to get close to the dent and take pictures. They called Maintenance and after conference with them they informed me that the checkup was going to take a few hours. I informed the gate agent and Dispatch and the flight was canceled. When and how the dent happened is totally unknown.
We swapped into this aircraft. I performed the walk around in moderate rain with overcast clouds. I did not note any defects. While taxiing to the Runway the Controller reported birds near the runway. We did not see any birds; and we reported that to ATC. We flew the first 15 to 30 minutes of the flight in rain. We had a normal landing at destination which was sunny with scattered clouds.While preparing to leave the gate for our return flight; a Ramp Worker came to the flight deck and reported that he noticed 'what appeared to be a hole at the top of the vertical stabilizer.' The Captain went outside to inspect the aircraft. He returned; and made a Maintenance writeup for what appeared to be a hole in the leading edge of the vertical stabilizer; approximately 1.5 ft from the top (about 40 ft above the ground). He called Maintenance Control with the writeup.Company Maintenance Techs happened to be present. They inspected the damage as best as they could; due to the height of the damage; and confirmed repair would be needed. The flight was canceled due to the required maintenance.
B737 flight crew reported they were informed of possible damage near the top of the vertical stabilizer. After maintenance examination; the aircraft was taken out of service.