History of Flight
On May 2, 2013, at approximately 1550 Pacific daylight time, a Robinson R44 II helicopter, registration N442RN, sustained substantial damage following a loss of control during takeoff near Pomeroy, Washington. The certified commercial pilot, the sole occupant, was not injured. The helicopter was operated by Leading Edge Aviation of Clarkston, Idaho, for an aerial application flight under 14 Code of Federal Regulations Part 137. No flight plan was filed, and visual meteorological conditions prevailed.
According to a statement from the pilot, the ground crewman prepared 800 gallons of spray solution for 165 acres. The pilot completed 11 loads from a loading spot adjacent to the field. He was hauling 50-gallon loads and refueling as needed. After spraying about 150 acres, he landed on the loading platform for another load. The helicopter was loaded with chemical and about 10 gallons of fuel was added. The ground crewman gave a thumbs-up signal indicating readiness to depart. As the pilot initiated forward flight, the low rotor RPM horn activated. He activated the emergency dump button, but the rotor RPM continued to decay. The pilot attempted a run-on landing in a stubble field, during which the left skid dug into the soil, causing the helicopter to nose over and come to rest on its left side.
A postaccident examination revealed substantial damage to the forward fuselage, main cabin, and tail section. The pilot reported no known mechanical anomalies with the airframe or engine.
Personnel Information
The pilot, age 33, held a commercial pilot certificate with ratings for rotorcraft-helicopter, helicopter instructor, and airplane single-engine land. He reported a total flight time of 1,911 hours, including 1,572 hours in helicopters and 1,262 hours in the same make and model as the accident helicopter. His most recent flight review was completed on December 5, 2012, in a Robinson R44 II. He had flown 270, 83, and 4 hours in the preceding 90 days, 30 days, and 24 hours, respectively. He received his most recent FAA second-class medical certificate on January 22, 2013, with no waivers or limitations.
Aircraft Information
The accident helicopter, N442RN, was a 2006 Robinson R44 II Raven, serial number 11047. It was a four-seat, single-engine helicopter with skid-type landing gear, powered by a 245-horsepower Lycoming IO-540-AE1A5 engine (serial number L-30772-48A). Maximum gross weight was 2,500 pounds. The helicopter received a Standard Airworthiness Certificate on January 19, 2006. Maintenance records showed an annual inspection on April 18, 2013. At the time of the accident, the airframe and engine had accumulated 1,615 hours, with 30 hours since the last inspection.
Meteorological Information
The pilot reported weather conditions at the time of the accident: wind calm, sky clear, visibility 10 miles, temperature 66°F (18.8°C), altimeter setting 30.48 inches of mercury. The pilot computed a density altitude of 4,008 feet.
Wreckage and Impact Information
On-site documentation by an FAA airworthiness inspector revealed that the main wreckage came to rest on its left side in a stubble field about 450 feet west-northwest of the departure point. The helicopter was oriented in a northwesterly direction. The tail rotor blades and associated assembly were located about 5 feet forward of the main wreckage. Both main rotor blades sustained substantial damage from impact forces. The spray booms and SIMPLEX spray system were partially attached to the fuselage and had impact damage. The two-place cockpit was intact with minimal damage.
Additional Information
In the accident report, the pilot commented that the chemical spray solution loaded was in excess of the 50 gallons he had requested, placing the helicopter outside weight and balance and performance limitations. He also noted that the spray tank's sight glass is long and shallow and provides inaccurate readings unless the helicopter is level. The pilot indicated that he had no visual ability to see the spray tank or know how much solution was loaded.
Tests and Research
During the investigation, the pilot stated that the amount of chemical on board is not visible during loading or inflight operations. To know the quantity, the pilot must rely on the ground crewman or physically deplane to view the sight gauge, as neither gauge is visible from the pilot seats. On May 16, 2013, the investigator-in-charge (IIC) visited SIMPLEX AEROSPACE in Portland, Oregon, the manufacturer of the Robinson R44 Simplex Model 244 spray system installed on the accident helicopter. SIMPLEX personnel provided an orientation; the IIC was not permitted to photograph the equipment. The spray tank is lightweight (186 pounds), chemical resistant, with a 130-gallon capacity. Features include a jettison door, dual spray valve, single and dual spray boom depressurization, and a self-contained system with attached spray boom. The IIC observed both sight gauges but could not determine visual limitations from the pilot positions without the helicopter present.