NTSB Factual Report

HISTORY OF FLIGHT

On September 4, 2008, about 1845 central daylight time, a Weatherly 620B airplane, N2036U, was substantially damaged when it impacted terrain following a loss of engine power during aerial application near Atkinson, Nebraska. Visual meteorological conditions prevailed at the time of the accident. The commercial pilot was not injured. The flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 137 without a flight plan. The local flight originated at the O'Neill Municipal Airport-John L Baker Field (ONL), O'Neill, Nebraska.

The pilot departed ONL to begin aerial application operations. The pilot flew one pass and made a climbing left turn to realign for a second pass. As he lowered the airplane nose the engine began to lose power. The pilot pushed the throttle and mixture controls forward in an attempt to regain power and turned towards a nearby pasture to land. The engine quit completely before reaching the pasture. The airplane impacted the ground and slid to a stop. During impact the engine separated from the fuselage and came to rest on the left wing.

PILOT INFORMATION

The pilot, age 21, held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. His last Federal Aviation Administration (FAA) second-class medical was issued July 17, 2008, with no limitations.

The pilot indicated on the National Transportation Safety Board (NTSB) Form 6120.1 he had 500 total hours and 100 hours in this type airplane at the time of the accident.

AIRCRAFT INFORMATION

The 1995-model Weatherly 620B, serial number 1596, was a low wing airplane, with a fixed, tail wheel landing gear, and was configured for one occupant. The airplane was powered by a direct drive, carbureted, air-cooled, nine-cylinder radial engine. The engine was a Pratt and Whitney R985AN-14B, serial number JP202792, rated at 450 horsepower, and was driving a Hartzell two-bladed, controllable pitch propeller.

The last airframe inspection was an annual type inspection, completed on May 31, 2008. The airframe had accumulated 2,874 hours at the time of inspection.

The engine was manufactured on June 20, 2005, and had accumulated 88 hours since its last overhaul. The engine overhaul was performed by Tulsa Aircraft Engines (TAE), Tulsa, Oklahoma. The engine had accumulated approximately 3,000 total hours at the time of the accident.

WRECKAGE AND IMPACT INFORMATION

The initial impact point was located in a flat, grassy pasture. The landing gear was collapsed and the airplane slid on its belly for several hundred feet before impacting a fence and rotating 180 degrees from the initial impact heading. The airplane came to a stop with the engine resting on the left wing near the fuselage. Buckling of the fuselage and firewall indicated the airplane impacted the ground about 10 degrees nose low.

The left wing had leading edge damage on the inboard five feet consisting of a gouge approximately one foot deep and leading edge crushing. The right wing had multiple gouges in the leading edge and the inboard five feet showed extensive crumpling. The gouges in both wings were consistent with impact damage with metal fence posts. Both wing tanks had been breached during impact and the fuel escaped from the tanks.

The presence of toxic chemicals at the accident site prevented the immediate recovery of the airplane. As a result, the airplane was exposed to the natural elements for several days, which included at least two days of rain showers. Additionally, the engine and wreckage were stored outdoors and uncovered for several weeks prior to the engine examination.

WEATHER

Weather at ONL at 1850 was 72 degrees Fahrenheit (F), dew point 41 degrees F, relative humidity 33 percent, and skies were clear with 10 miles visibility.

The FAA pamphlet, "Tips for Winter Flying", carburetor icing chart showed no carburetor icing conditions at the time of the accident

TEST AND RESEARCH

The airplane operator had a second airplane conducting operations from the same location as the accident airplane. The second airplane had been fueled from the same tank as the accident airplane. The operator checked the fuel in the second airplane shortly after the accident and found no water or contaminants.

The engine was taken to TAE for analysis and warranty repairs. The engine analysis was conducted with FAA oversight on November 26, 2008. The engine was delivered to TAE by the airplane owner. It arrived at TAE strapped to a pallet and it had not been covered during shipment.

Initial examination of the engine showed the number two and number seven cylinders were cracked in a manner consistent with impact damage. The carburetor and fuel pump were removed from the engine, the number two and number seven cylinders were replaced, and the oil transfer tubes were replaced, and an engine run was conducted. The engine run was conducted in a test cell and it met all performance criteria. No other defects were noted.

Inspection of the carburetor revealed corrosion consistent with water exposure on internal components, to include the finger filter.

The fuel pump was removed from the engine and disassembled at Quality Aircraft Accessories, Tulsa, Oklahoma, under FAA oversight. The pump arrived intact. The inlet fuel fitting was present and the inlet fuel line was completely separated at the inlet fitting. Fuel line fracture surfaces were characteristic of impact damage. The overboard vent tube with fittings and the fuel outlet fitting and fuel line were attached to the pump.

The inlet fitting was removed and there was evidence of rust on the blades and inlet portion of the fitting. The outlet fitting was removed and there were no discernable defects noted. The pump seal nut was removed and there was evidence of oil, contaminants, and minor heat damage to the bearings. The rotor assembly was removed and there was evidence of water damage, rust deposits in the pump interior, liner, lower journal, and bearing. The deposits were excessive and impeded proper functioning.

NTSB Probable Cause

The total loss of engine power due to water contamination and corrosion within the fuel system at an undetermined time and from an undetermined source.