The certificated flight instructor was providing dual instruction under Title 14, CFR Part 91. The flight instructor said during landing the student over-corrected with the rudder, causing the airplane to swerve to the right, and then over-corrected again by applying full left rudder. He said as he attempted to take control of the airplane, the student applied full right rudder, and the airplane swerved to the right. The instructor said the swerve to the right was more than he could correct, because there are no brakes on the rudder pedals on the right side of the airplane. He said the airplane ground-looped to the right, and the left main landing gear collapsed, resulting in structural damage to the left wing and fuselage. The instructor said there were no known mechanical problems with the airplane prior to the accident. In his written report to the NTSB, he wrote: "I should have recognized the student's over controlling sooner, and assumed control of the airplane prior to the ground-loop actually happening."