A CFI and pilot receiving instruction were landing a tailwheel-equipped Cessna 172N at the airport in Loveland, Colo. The CFI reported that after touchdown the airplane veered to the right. He took control of the plane and applied full left rudder and left brake.
The plane tracked straight for a moment before it turned right and departed the runway.
The left main landing gear collapsed and the left wing hit the ground.
Examination of the right brake rotor revealed heat damage (bluing) of the rotor and substantial damage to the wing and fuselage.
The instructor noted that the other pilot did not appear to make any control inputs that would have resulted in a right turn.
The NTSB determined the probable cause as a dragging right brake, which resulted in an un-commanded right turn, and subsequent ground loop.
NTSB Identification: CEN14CA055
This November 2013 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.