The pilot reported that he had planned a local flight with a passenger, and had carried out his pre-flight checks and started the engine, when he noticed a split pin which was seated incorrectly. He shut the engine down, exited the aircraft, attended to the pin, re-boarded, and started the engine again.
The aircraft took off normally but, at a low height, the engine power reduced. The pilot decided to land on the remaining runway ahead. The aircraft touched down but did not stop by the end of the runway, and struck a fence. Neither occupant was injured but the aircraft sustained damage.
The pilot reported that after the aircraft had come to rest, he found his passenger’s headset cable wrapped around the choke cable, and the choke about ⅓ open. He considered that this was a possible cause of the power loss, and that the interruption of his normal checks caused by the split pin may have prevented identification of the headset cable problem; although he had checked the choke position before the first engine start, he had not repeated this check after the second one.