On July 29, 2010, at 0930 eastern daylight time, a Hiller UH-12E, N104HH, registered to and operated by Haddock Flying Service Inc., collided with a tree during an autorotation following a total loss of engine power near Holly Hill, South Carolina. The aerial application flight was operated under the provisions of 14 Code of Federal Regulations Part 137, with no flight plan filed. Visual meteorological conditions prevailed. The certificated commercial pilot received serious injuries, and the helicopter was substantially damaged. The flight departed from a landing pad in Holly Hill, South Carolina, at 0925.

The pilot stated that as he approached a tree line for aerial application, his chemical ran out. As he turned back to reload chemical the engine experienced a total loss of power. Due to the low operating altitude he quickly conducted an autorotation and collided with trees before coming to rest on the ground.

Examination of the wreckage by a Federal Aviation Administration inspector revealed that the helicopter collided with a tree during the autorotation which resulted in substantial damage to the fuselage and the main rotor assembly. Flight control continuity was confirmed from the cockpit through the tail rotor system, and from the cockpit cyclic and collective controls through the main rotor head. Further examination of the helicopter revealed that fuel was present in the fuel tank. The helicopter was recovered for further examination.

An examination of the engine revealed that the combustion chamber fuel spray nozzle was clogged with carbon and soot deposits. A review of the engine maintenance logbooks revealed that the most recent 100-hour inspection was completed 41 days prior to the accident. According to the aircraft Hobbs time, the engine accumulated 40 hours since the 100-hour inspection. A review of the engine logbooks did not reveal documentation of the inspection or the cleaning of the fuel spray nozzle. A review of the Rolls Royce 250-C20 series operation and maintenance schedule inspection pages revealed that at the 100-hour inspection, item 21.A states: "remove, inspect and clean the fuel nozzle. If no airframe mounted fuel filter is installed, inspect the fuel nozzle filter." It also noted that operators may find it necessary to inspect and clean the fuel nozzle more often depending on past experience or operating conditions.