On August 17, 2011, about 1500 Pacific daylight time, a two seat tandem seating configuration Piper J3C-65, N3453K, was not damaged during an engine start at the Rohnerville Airport (FOT), Fortuna, California. The airplane was registered to and operated by the commercial pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot and his passenger were not injured and one person assisting in starting the airplane sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The flight had not departed at the time of the accident and had an intended destination of Garberville, California. In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that as he was briefing his wife, a non-pilot rated passenger, that he would hand prop the engine while she operated the throttle and brakes, the father of one of his previous students approached him and told him to get inside the airplane and that he would "do the propping." The pilot stated that he was unsure of the individual's experience, but noted that the person's daughter, who he had previously instructed in the airplane, was present. The daughter of the individual hand propping the engine communicated to the pilot "…brakes, throttle cracked, stick back, and mags on,” both followed by her father pulling the propeller through. The pilot stated that the engine start was unsuccessful and that before he could turn the magnetos off, the individual motioned towards the propeller and pulled it through despite him yelling "it's hot." The engine subsequently started and the individual was struck on the forearm. The pilot questioned the individual if he was ok and was assured he was and that it was just a glancing blow. In a statement submitted to the IIC, the non-pilot rated individual, who hand propped the airplane reported that after taking a photo of his daughter, the pilot and the pilot's wife in front of the airplane, the pilot's wife got into the front seat and the pilot climbed into the rear seat. After taking the picture the individual then moved to the propeller, with his daughter positioned outside and on the right side of the airplane. The individual stated that the pilot called out something similar to “let's give it a try” as he relayed to the pilot “brakes on, mags off, clear” prior to pulling the propeller through. The engine did not start and the pilot called out to the individual's daughter to prime the airplane's engine. The individual's daughter then reached into the cockpit area, primed the engine, and moved back away from the airplane. The individual further stated that the pilot told him to "...go ahead and turn it over three times." The individual said that he complied with the pilot's instructions without calling out “brakes on, mags off, clear.” The individual said that he pulled the propeller through with his left arm and that while reaching out to grab the other propeller blade with his right arm, the engine started and struck him in his right forearm. The individual added that at no time while he was pulling the propeller through following the initial attempt to start the engine did the pilot communicate with him. Several weeks after the accident, the IIC was notified that the individual who was performing the hand propping eventually got an x-ray of his forearm, and it was determined that the bone was broken.