Accident Summary
On March 25, 2011, at 1238 eastern daylight time, a Hiller UH-12E helicopter, registration N4033P, was substantially damaged during a forced landing. The event occurred while the helicopter was surveying an area for spraying near Culpeper, Virginia. The pilot, the sole occupant, was not injured. The flight was conducted under 14 CFR Part 137 as an aerial application flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from a nearby open area on the pilot's property around 1215.
According to the pilot, while flying approximately 150 to 200 feet above ground level, he noted an uncommanded high engine rpm. The helicopter then turned about 60 degrees in heading and experienced a loss of lift. The pilot reduced the collective and initiated an autorotation. After the helicopter came to rest, the pilot exited and reported that the transmission was "hot" and the transmission cooler was "the same temperature as the outside air temperature."
Photographs provided by a Federal Aviation Administration (FAA) inspector showed the helicopter resting on the hopper used to carry the applicant, leaning about 45 degrees to the left. The tailboom was severed, and the main rotor blades were damaged.
Pilot Information
The 55-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, rotorcraft-helicopter, and instrument airplane. He reported 12,382 total flight hours, with 1,500 hours in the accident helicopter make and model. His most recent FAA second-class medical certificate was issued on October 12, 2010.
Aircraft Information
The helicopter was manufactured in 1982 and equipped with a Lycoming VO-540-C2A, 315-horsepower engine. It was registered with the FAA in the standard-restricted category and used for aerial application. The most recent continued airworthiness inspection and engine overhaul were completed on March 18, 2011. At that time, the helicopter had accumulated about 3,340.4 total hours of operation, with a Hobbs meter time of 250.6 hours.
During the inspection, the main rotor transmission was removed to facilitate engine removal and overhaul. The transmission oil was drained, and the oil filter was inspected, with "no metal detected." The transmission gear box was reinstalled and serviced with oil as required per the Hiller Maintenance Manual. An engine run and flight test were completed, and "all test results [were] within parameters" and "all systems were operating normally." The helicopter had flown 1.8 hours since the last inspection and engine overhaul.