History of Flight
On August 7, 2012, about 0715 Pacific daylight time, a Hiller UH-12D helicopter, registration N47035, experienced a hard landing in a clear-cut forest area in Deer Island, Oregon. The pilot, who sustained minor injuries, reported that the helicopter had been spraying herbicide since about 0625. After completing six spray runs, the pilot refueled with 35 gallons of Jet-A fuel for the turbine-powered helicopter and began the seventh run. While making a right turn at an altitude of about 45 feet above ground level, the pilot felt a shudder. The helicopter then emitted a loud bang, began shaking, and the pilot lost significant control. The helicopter skidded to the right while descending, struck the ground, and rolled onto its right side. The pilot shut down the engine, turned off the battery master switch, unbuckled the restraint harness, and exited.
Personnel Information
According to Federal Aviation Administration (FAA) records, the pilot held a commercial pilot certificate with a helicopter rating. The operator reported that the pilot had accumulated approximately 6,075 total flight hours, all in helicopters. The most recent flight review was completed in November 2011, and the most recent FAA second-class medical certificate was issued in July 2012.
Aircraft Information
FAA information indicated that the helicopter, serial number 1074, was manufactured in 1959. It was originally equipped with a Lycoming VO-435 series piston engine. In 1985, it was modified with an Allison 250-C20 series turboshaft engine and re-registered with the FAA in the restricted category by Western Helicopter Services, Inc. At the time of the most recent annual inspection in June 2012, the helicopter had a total time in service of about 18,069 hours.
Meteorological Information
An on-site witness reported a thin overcast layer at about 2,000 feet above ground level with unlimited visibility. The wind was from the northwest at 2 mph, with no noticeable gusts or turbulence.
Wreckage and Impact Information
The wreckage was recovered by the operator before investigative personnel could examine it on site. A post-removal examination of the accident site by an FAA inspector did not yield additional components or information. The helicopter came to rest on its right side in a clearing near a road. An impact skid mark and a portion of the tail boom were found on the road. The transmission and main rotor blade assembly were found adjacent to and fracture-separated from the engine and airframe. Both main rotor blades were substantially damaged. The right side of the cockpit and cabin were crushed and deformed. No post-crash fire occurred.
The tail rotor slip joint and the forward flange of the tail rotor drive shaft were examined at the National Transportation Safety Board Materials Laboratory; no pre-existing mechanical deficiencies such as corrosion or fatigue cracks were detected. The operator considered the possibility of a compressor stall and sent unspecified engine components to an engine repair facility. That examination did not detect any abnormalities with those components.