B737-800
Human-Machine Interface
Aircraft Equipment Problem Critical
Aircraft Aircraft Damaged; General Maintenance Action
Aircraft; Company Policy; Human Factors; Weather
Inbound aircraft arrived at gate during snowfall. Inbound crew left flaps at 15. The Captain performed the walk around including a flap well inspection. I arrived at aircraft as Captain entered Jet Bridge. He was followed by the fueler who asked if he could fuel the aircraft with the flaps down. Captain informed me that he had inspected the flap areas and observed no contamination.  He decided to send me outside to clear the flap area while he raised the flaps. After I gave the Captain the all clear he raised the flaps. I observed no anomalies during flap retraction. The time from the Captain completing the exterior inspection until the flaps were raised was less than five minutes. We taxied to remote de-icing pad with flaps up. De-iced with type 1 and anti-iced with type 4. We then taxied to the runway with flaps retracted and set flaps to 15 just prior to takeoff. Taxi from de-ice pad to active runway was accomplished on surfaces that were treated and plowed. Runway was not contaminated. We performed a Flaps 15; 26K max power takeoff.  Flight was uneventful. All flap limit speeds were observed. A 30 flap landing was accomplished at destination.  After landing the flaps were retracted with no abnormal cockpit indications. As we were scheduled to keep this airplane; I began an exterior preflight inspection. I noticed that both inboard trailing edge flaps appeared partially extended while other flaps and slats were retracted. I informed the Captain and Maintenance. Once Maintenance arrived they had us fully lower the flaps and then discovered damage.  I am confident that we complied with all appropriate procedures. I do not know what caused this event; therefore I am unable to give a clear suggestion.  At a minimum we should review procedures to see if there is anything we should change regarding snow/ice operations.
B737-800 First Officer reports discovering inboard TE flap damage during preflight after bringing the aircraft in from a snow and ice impacted airport. The aircraft had been received at that airport with the flaps extended and were inspected prior to retraction at the gate. No anomalies were noted in flight.