History of Flight
On July 25, 2011, at approximately 1130 central daylight time, a Sikorsky UH-34D helicopter (registration N3880J) impacted terrain while spraying fungicide on a corn field near Wilton, Iowa. The certificated airline transport pilot received fatal injuries, and the helicopter sustained substantial damage, including postimpact fire. The aircraft was registered to US Helicopter LLC and operated by Southern Helicopter Services LLC 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 field about 3/4 mile from the accident site at approximately 1125.
The pilot landed the helicopter near the field to be sprayed and loaded it with 5 gallons of fungicide, 250 gallons of water, and 150 gallons of 100 octane fuel. Loaders were uncertain of the actual weight but determined that takeoff weight should not have exceeded the maximum.
According to the FAA, the pilot flew toward the field to conduct an aerial survey at an altitude near powerlines, which were about 40-50 feet above ground level. While flying south along the eastern edge of the field, the helicopter entered an out-of-ground-effect hover. A left pedal turn was performed, and the helicopter descended, impacting trees and terrain.
A witness reported that the helicopter flew south over his farm, then began to turn and pitch, "shuttered and sputtered," and descended out of view.
Personnel Information
The pilot held an airline transport pilot certificate with multiengine land and commercial privileges, including single-engine land, rotorcraft-helicopter, and instrument helicopter ratings. On January 12, 2011, he added a rotorcraft-helicopter rating to his flight instructor certificate. He also held a mechanic certificate with airframe and powerplant ratings.
According to an application dated July 9, 2011, for an SK-58 type rating, the pilot reported 10 hours in SK-58-CH34C and 8,000 total rotorcraft hours. A logbook from April 5, 2005 to January 12, 2011, showed 12,273.2 total flight hours, including 8,637 helicopter hours. Subsequent logbook pages were blank except for endorsements. An undated endorsement for the SK-58 type rating was provided by the recovery service. No training records or subsequent logbook records were received.
Aircraft Information
The 1961 Sikorsky UH-34D (serial number 148821) was powered by a Wright Cyclone R1820-84C engine (serial number 523464). Maintenance records indicated the last 15-, 50-, 100-hour, and annual inspection occurred June 21, 2011. The engine had a 100-hour inspection signed by an A&P mechanic at 1,933.9 hours total time and 133.9 hours since overhaul.
According to the flight manual, the UH-34D had a main rotor diameter of 56 feet. The latest type certificate data sheet (TCDS), dated January 24, 2005, showed that using 100/130 octane fuel instead of 115/145 reduced takeoff power and manifold pressure. Maximum gross weight was 12,500 lbs. An exemplar weight and balance form for another H-34 listed a restricted weight of 13,000 pounds and useful load of 5,431 pounds.
The operator reported that weight and balance information for N3880J was kept in the helicopter but was not recovered. The operator estimated a useful load of 1,100-1,200 pounds with 75 gallons of fuel. The pilot reported his weight as 190 pounds on July 16, 2011.
Meteorological Information
The Iowa City Municipal Airport (IOW) ASOS, 23 nautical miles west of the site, recorded at 1152: wind calm, visibility 10 miles, clear skies, temperature 28°C, dew point 21°C, altimeter 30.01 inHg. The Davenport Municipal Airport (DVN) ASOS, 20 nautical miles east, recorded: wind variable at 3 knots, visibility 10 miles, clear skies, temperature 28°C, dew point 20°C, altimeter 30.01 inHg. Relative humidity was 65.83% at IOW and 61.9% at DVN. Pressure altitudes were 558.6 feet at IOW and 673 feet at DVN.
Wreckage and Impact Information
The main wreckage came to rest in a wooded area near the field. Broken tree limbs rested on the wreckage, and a postimpact fire ensued. Examination at a salvage facility revealed postaccident fire damage and sooting on the airframe, engine, rotor systems, transmission, and flight controls. Fire consumed the fuselage from nose to pylon, main rotor hub assembly, and main landing gear.
Main rotor blades were cut near the root during recovery; root sections were attached to the hub, and tree material was embedded in control linkage. All four blades exhibited bending and/or trailing edge impact damage. The pylon separated mid-span, and the tail rotor assembly remained intact with all four blades attached, each bent 90 degrees at mid-chord consistent with rotation.
All engine cylinder assemblies were intact except one; its piston face was not damaged and contained no embedded debris. Damage precluded functional testing. No mechanical anomalies were noted that would have precluded operation.
Medical and Pathological Information
On November 27, 2001, the pilot had received an Order of Revocation of his medical certificate for an incorrect statement. His last medical certificate, issued July 5, 2011, was second-class with a restriction: "Must have available glasses for near vision."
An autopsy conducted July 26, 2011, listed cause of death as "Multiple blunt force and thermal injuries." The FAA toxicology report detected no carbon monoxide, cyanide, ethanol, or drugs.
Tests and Research
Performance charts from the NAVTOPS Flight Manual were based on 115/145 octane fuel. The Take-Off Gross Weight Limitation chart, based on maximum power and 2,800 rpm, showed that at conditions recorded by IOW and DVN, a weight of 13,000 lbs yielded 0 fpm climb rate, increasing to 300 fpm at 12,450 lbs.
The Rotorcraft Flying Handbook notes that during a left turn, additional power is required because left pedal increases tail rotor pitch angle. It also describes ground effect as typically occurring less than one rotor diameter above the surface, and that vertical ascent without forward speed increases induced drag and power demand. The handbook discusses vortex ring state (settling with power), characterized by uncommanded pitch and roll oscillations and little cyclic authority during vertical descent with power applied.