History of Flight
On May 4, 2013, at 0012 mountain standard time, an Arrow Falcon Exporters OH-58A+ helicopter, registration N911RN, collided with terrain during crop application operations near Somerton, Arizona. The commercial helicopter pilot was not injured. The helicopter came to rest on its right side, resulting in substantial damage. The helicopter was registered to Morris Equipment LLC and operated by Morris Ag Air as a 14 Code of Federal Regulations Part 137 aerial application operator. Night visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated from Yuma International Airport, Yuma, Arizona, and was destined for Somerton.
The pilot stated that he was applying product to a field and was completing his 15th load of the night. The target field was a narrow field with tall power lines along one side. The pilot approached the field, made a right turn to parallel the field, then a wide left turn to align the helicopter with the length of the field. While in the left turn, the pilot continued to apply left cyclic until it hit the stop. The helicopter continued to drift right towards the power lines. The pilot applied up collective and left pedal to maneuver over the power lines when the helicopter started to rotate to the right in an uncommanded fashion. The helicopter collided with terrain as the pilot attempted to regain directional control. The pilot stated that the helicopter and engine had no mechanical failures or malfunctions during the flight.
Pilot Information
The pilot, age 36, held a commercial pilot certificate for helicopters with an instrument helicopter rating issued on June 6, 2009, and a flight instructor certificate with ratings for helicopter and instrument helicopter, issued on February 2, 2012. He held a second-class medical certificate issued on February 6, 2013, with no limitations. The pilot reported having 650 total flight hours, all in rotorcraft, and 250 hours in the OH-58. He had 40 total night hours, accumulating 18 hours of night time within the previous 30 days. This was the first season he had been employed as a pilot for crop application operations. He reported that on the day of the accident he flew a practice flight at 0730, went home at 0900, took a 1-hour nap, returned at 1500, went home at 1700, and returned at 2030. He took off at 2130, which commenced his working flight. At the time of the accident, it had been 14 hours since the pilot's last sleep period.
Aircraft Information
The conventionally configured helicopter, serial number 69-16273, was manufactured in 2006. It was powered by a Rolls Royce T63-A-720 turboshaft engine rated at 420 horsepower. The operator reported that the most recent annual inspection was completed on February 27, 2013, at a total airframe time of 6,729.3 hours. Engine total time was 5,058.1 hours, time since major overhaul was 4,964 hours, and time since inspection was 94.1 hours. The helicopter was equipped with work flood lights aimed out ahead of the helicopter, used while performing crop application work at night.
An Arrow Falcon Exporters, Inc., model 3900-OH58 Spray System was installed on the helicopter under Supplemental Type Certificate SR00268LA. The system consists of two 70-gallon cylindrical chemical tanks attached by quick disconnect pins on the left and right sides of an "H" frame support bolted to the hard points of the landing gear attach fittings. The tanks are connected through a cross feed tube that allows filling from either side. Chemical is routed through the cross feed tube to a center outlet and then to the chemical pump. The center spray boom is 70 inches long and mounted at airframe station 22 on the "H" frame support. It accommodates 12 spray nozzles or down tubes. Outboard spray booms connect to the center boom and are supported by vertical and horizontal struts.
Meteorological Information
Marine Corps Air Station Yuma meteorological report for May 3, 2013, at 2357 reported visibility of 10 statute miles, broken cloud layers at 18,000 and 25,000 feet; temperature 26°C; dew point 2°C; and an altimeter setting of 29.73 inHg. Astronomical data from the US Naval Observatory for the accident location (latitude N32°36', longitude W114°43') on May 4, 2013, showed sunset at 1932, moon rise at 0233, and moon set at 1441. The fraction of the moon illuminated was 31% after moon rise.
Wreckage and Impact Information
The helicopter was found on its right side by first responders. A small fire observed in the engine compartment was extinguished a few minutes later by the Fire Department. The main rotor was attached to the drive transmission; both rotor blades were attached to the rotor hub, with each blade extending about half span from the hub and the outboard half not attached. Both chemical product tanks were attached to the airframe, and the deformed spray boom remained attached. The tail boom aft of the fuselage transition splice had separated and was lying next to the fuselage upper deck. The tail rotor had been severed from the end of the tail boom. A Federal Aviation Administration inspector examined the wreckage and did not identify any evidence of a mechanical failure or malfunction.