On January 18, 2014, about 1200 eastern standard time, a Piper PA-12, N3668N, was substantially damaged following a hard landing at Zephyrhills Municipal Airport (ZPH), Zephyrhills, Florida. The private pilot and one passenger were not injured. The airplane was operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day, visual meteorological conditions prevailed for the flight, and no flight plan was filed. The flight originated from Tampa North Aero Park (X39), Tampa, Florida, about 1130. The pilot reported that he was number two of a formation flight of two and was landing on runway 4. He reported surface winds at the time to be from 275 degrees at 15 knots with gusts to 25 knots. The approach to landing was normal and the airplane touched down "a little long past the numbers due to the tailwind." A gust of wind then lifted the left wing high while he already had full left aileron controls in. He added power while attempting to recover, the left wing descended, and the left main landing gear collapsed as the airplane landed hard. The airplane ground looped around the failed gear and came to a stop. An inspector with the Federal Aviation Administration responded to the accident site and inspected the wreckage. He reported that the left main gear collapsed, resulting in structural damage to the lower fuselage. Structural damage was also observed on the left wing. The pilot reported that the main gear safety cable "failed" and cut the landing gear bungees during the hard landing. The safety cable was subsequently removed by the pilot and was forwarded to the NTSB Investigator-in-Charge for further examination. The braided steel cable was about 19 inches in length and was fitted with attachment hardware on each end. The failure point was approximately 12 inches from one end (or 7 inches from the opposite end). The failed ends exhibited a "broomstraw" appearance, consistent with tension overload. Inside the strands on one failed end were light-colored fibers that were consistent in appearance with the landing gear bungee material. The purpose of the landing gear safety cable was to prevent airframe damage in the event of a failure of the landing gear bungee(s). Due to the landing gear and airframe damage, the position of the landing gear safety cable prior to the hard landing could not be determined.