On July 29, 1994, at 1620 hours mountain standard time, a Cessna 421C, N985RA, sustained substantial damage during a landing overrun at Polacca, Arizona. The aircraft was operated by Life Flight and was on a revenue flight under 14 CFR Part 135 of Federal Aviation Regulations. Visual meteorological conditions were prevalent at the time of the accident and a company (VFR) flight plan had been filed for the operation. Neither the certificated airline transport pilot, the two crew members, nor the two passengers were injured. The flight originated from Flagstaff Pulliam airport at 1550 on the day of the accident. The pilot reported that he observed the windsock hanging limp and initiated an approach to runway 22. After turning final, he noticed that the aircraft floated more than usual and he suspected a tail wind. The approach speed and descent rate were normal. Upon touchdown, a bird impacted the copilot's windscreen and he said he may have delayed braking as he attempted to avoid the flock. After touchdown, the braking action was less than normal because of the roughness of the tar and dirt build up on the runway surface. By the time he was able to slow the aircraft's landing roll to approximately 10 knots, he had overrun the runway. He immediately noticed the aircraft was rolling into soft sand and was attempting to use his momentum to make a 180- degree turn back to runway when the nose gear collapsed.