What happened
On the date of the accident, a flight instructor was providing instruction to a private pilot/new owner in a tailwheel airplane equipped with tundra tires. The student pilot had accumulated 60 total flight hours, including only 0.5 hours in this specific aircraft. Five minutes after takeoff, while performing a landing on an asphalt runway that contained ice along the edges, the aircraft began to drift toward the right side of the runway.
In an attempt to correct the drift, the instructor applied left rudder; however, the airplane departed the right side of the runway and entered an area of snow. The aircraft then nosed over, resulting in damage to the propeller, fuselage, and wing lift struts. There were no injuries reported.
The investigation
The investigation focused on the right master brake cylinder, which had been serviced prior to the flight. A heater hose had been installed in the cabin to direct heat toward the rear seat area where the instructor was seated. The instructor noted that the right brake felt as though it were locked, suggesting the lock may have been caused by overfilling the brake reservoir or the heating of the brake cylinder by the heater hose.
Review of previous NTSB reports revealed two other accidents in 1997 where aircraft experienced locked brakes during landing. In both prior cases, a heater hose had been directed onto master brake cylinders following service. One of those incidents occurred after 1.5 hours of flight time, and the other after 3 hours of flight time. The brake system of this aircraft was not examined following the accident.