On April 1, 1998, approximately 1540 Pacific standard time, the left main gear of a Cessna 195A, N1069D, separated from the aircraft during the landing roll at Bend Municipal Airport, Bend, Oregon. The certified flight instructor and his student, who is a private pilot, were not injured, but the aircraft, which was owned by the student, sustained substantial damage. The 14 CFR Part 91 instructional flight, which had been in the air for about 40 minutes, was being operated in visual meteorological conditions. No flight plan had been filed, and there was no report of an ELT transmission. According to the CFI, the student, who had recently purchased the aircraft, allowed the aircraft to drift toward the right edge of the runway during the landing roll. At the point where it looked like additional corrective action was necessary, the instructor took control and applied left brake and left rudder. At that point the left main gear leg fractured where it protrudes from the gear leg attach box. NTSB examination of the fracture surface revealed that two separate fatigue cracks had initiated in an area of corrosion generated by the gear leg rubbing on the gear leg clamping system. These two cracks had combined and formed a united crack front. When loads were applied to the gear leg during the landing roll, an overstress separation stemming from the fatigue fracture region occurred.