Skyhawk 172/Cutlass 172
Flight Crew Private
Flight Crew Last 90 Days 5.6; Flight Crew Total 85; Flight Crew Type 85
Situational Awareness
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Object
Aircraft Aircraft Damaged; General Maintenance Action
Human Factors
During approach; I noticed I was coming in too low. I added power to touch down on the runway threshold without incident. Upon landing; my instructor mentioned that I may have hit a runway light; although I did not believe I had. After coming to a full stop and taxiing back to hold short of runway on taxiway; we noticed a broken light and some debris at the edge of the runway. We reported to [the] Tower that we may have hit a light during landing and were advised that we had landed clear of the threshold and it must have been another airplane. My instructor and I both looked outside our windows and observed no damage to the landing gear or airplane; but told the Tower that we saw debris on the runway. We proceeded with our pattern work with no further incident or observation of anything awry. I did not note any damage to the aircraft during my post-flight review. The following morning; upon further visual inspection of the aircraft; damage was noticed to the underside of the right horizontal stabilizer of the aircraft which was then grounded for maintenance. Our best guess is that we may have hit existing debris on the runway which bounced back and hit the underside of the horizontal stabilizer. In retrospect; we probably should have exited the aircraft for a full visual inspection based on my instructor's suspicion that we may have hit something and seeing debris on the runway upon taxiing back to the hold-short lines regardless of being told by the Tower that we had not made contact with anything on landing.
On landing I noted a thump from the left size of the aircraft. A full stop was conducted and a taxi back to the runway was requested. Visual examination of the aircraft from the right seat revealed no damage to the aircraft. Upon entering runway; a piece of FOD was observed on the runway. ATC confirmed that our aircraft touch down past the runway lights on the previous landing; and could not have struck the lights. Faced with only an instructor's unease; and the Tower's comment that we did not strike the light; I concluded that we were not damaged and depart on the runway for another turn in the pattern; and concluded the flight without incident.What we should have done is [a] complete walk around of the aircraft. If you feel something is wrong; it should be investigated fully. Only through visual inspection of the aircraft would have revealed this damage.A later inspection of the aircraft uncovered significant damage to the underside of the right horizontal stabilizer.
A pilot and flight instructor observed runway light debris on the runway but were advised by The tower that they had landed clear.  They did not exit the aircraft to inspect for possible damage.  Later; they discovered damage to the horizontal stabilizer.