On March 17, 2010, about 1530 Alaska daylight time, a ski-equipped Cessna 170B airplane, N3492C, sustained substantial damage when the main landing gear collapsed during taxi for takeoff, at Lake Hood Seaplane Base, Anchorage, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal local flight under Title 14, CFR Part 91, when the accident occurred. The airline transport pilot and sole passenger were not injured. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on March 18, the pilot said he was taxiing for takeoff on Lake Hood when the right main landing gear leg broke near where the leg exits the fuselage. He said when the leg broke the right wing impacted the ground, bending the wing from the aileron outward toward the tip. He said there were no mechanical problems with the airplane prior to the accident. During a meeting with the NTSB IIC on March 25, the pilot presented the broken gear leg to the IIC and an FAA air safety inspector. The break appeared to be a single linear break perpendicular to the leading edge of the gear leg. The break was about 6 inches from the gear leg mounting bolt hole, at the widest portion of the gear leg. No other damage was observed. The gear leg was retained by the FAA inspector for metallurgical examination.