Thursday, March 29, 2018

Robinson R44 Raven II, N165RV: Accident occurred May 13, 2015 in Columbia, Illinois


The helicopter experienced a loss of engine power during an agricultural application flight at low altitude. The commercial pilot lowered the collective and increased the throttle but was unable to reestablish engine power, so he made a run-on landing to a field. During landing, the right skid sunk into the mud/wheat, which caused a "slight hop," and the main rotor struck the tailboom.

Postaccident examination of the oil filter revealed no signs of contamination. No mechanical anomalies were noted with the fuel system and the fuel from the carburetor was light blue, typical of 100 low-lead aviation fuel. An unidentified sticky substance, likely agricultural spray, coated the lower half of the throttle flap and the bottom half of the fuel injector body. However, the observed buildup of the substance was not sufficient to restrict the throttle flap from actuating.

The refueling station used for the spraying operations consisted of a large storage tank attached to a trailer, a filtering unit, and a supply hose, which was connected to the refueling tank. The supply hose had been purchased from a farm supply store, and its exterior was stamped with "farm fuel transfer hose w/static wire." According to the manufacturer's packaging label, the supply hose was not designed to dispense aviation fuel. Samples of fuel were collected from inside the refueling tank and the supply hose; the sample from the hose was pale green, indicating that some type of contamination was present, and the sample from the tank was light blue. Laboratory analysis of the fuel samples from the refueling tank and supply hose showed that they were substantially identical; however both had a high "unwashed gum" content from different sources; the unwashed gum content in the hose sample was consistent with an additive used in plastics and rubber hoses; whereas, the unwashed gum content in the fuel tank was consistent with a stabilizing additive common in fuels. However, it could not be determined whether the unwashed gum content from the hose would have affected engine operation. 

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
A total loss of engine power while maneuvering at low altitude for reasons that could not be determined during postaccident examination.


Fuel - Not specified
Hoses and tubes - Incorrect use/operation

Environmental issues
Soft surface - Contributed to outcome

Not determined
Not determined - Unknown/Not determined (Cause)

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; St. Louis, Missouri

Aviation Accident Final Report - National Transportation Safety Board:

National Transportation Safety Board - Aviation Accident Factual Report

Location: Columbia, IL
Accident Number: CEN15LA231
Date & Time: 05/13/2015, 1730 CDT
Registration: N165RV
Aircraft Damage: Substantial
Defining Event: Fuel contamination
Injuries: 1 None
Flight Conducted Under: Part 137: Agricultural 

On May 13, 2015 about 1845 central daylight time, a Robinson Helicopter R-44, N165RV, impacted terrain following a loss of engine power during an aerial application flight near Columbia, Illinois. The helicopter was substantially damaged, and the commercial pilot was uninjured. Visual meteorological conditions prevailed at the time of the accident and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 137 local flight.

The pilot reported he had made 2-4 passes over the field with spray when he heard the Low Rotor RPM horn and the engine "went silent." He estimated he was approximately 5-10 feet above ground level (agl) when the loss of engine power occurred. The pilot lowered the collective and increased throttle but there was no reaction from the engine. He then slowed the helicopter's ground speed as much as possible and performed a run-on-landing to the field. The pilot reported that as the helicopter touched down the right skid sunk into the mud/wheat, which caused a "slight hop" to the right and the main rotor impacted the tail boom.

On June 11, 2015, Federal Aviation Administration (FAA) inspectors provided oversight of an examination of the helicopter at a maintenance facility in Cahokia, Illinois. The throttle, mixture and fuel shutoff controls were checked for correct freedom-of-movement and condition with no anomalies noted. The oil filter was removed, cut open and revealed no contaminants. A sample of fuel from the fuel strainer assembly revealed a blue colored liquid that was consistent with uncontaminated 100 low-lead aviation fuel. The contents of the fuel strainer bowl was poured through a clean white paper towel and no debris was observed. The fuel filter showed no signs of particulate contamination. The engine inlet air filter element exhibited a sticky residue on the exterior side of filter; however, the filter element looked clean and free of debris. Upon removal of the air filter, it was discovered that an unknown sticky substance coated the lower half of throttle flap and the bottom half of the fuel injector body. The buildup of residue was less than 1/32 inch at the thickest point, located at the base of the inlet portal. Despite the presence of the unknown sticky substance, the throttle flap was able to rotate normally.

The refueling station used for the spraying operation consisted of a large storage tank attached to a trailer. The tank was equipped with a filtering unit and supply hose. The supply hose was purchased from a farm supply store and contained a stamp on the exterior of the hose indicating "farm fuel transfer hose w/static wire." The supply hose was subsequently identified as an non-aviation refueling hose that was intended to dispense gasoline, diesel, and oil, according to the manufacturers packaging label. According to FAA Advisory Circular 150/5230-4B, "Aircraft Fuel Storage, Handling, Training, and Dispensing on Airports," the FAA has adopted standards used in National Fire Prevention Agency (NFPA) 407, Standard for Aircraft Fuel Servicing. NFPA 407 provides a standard for the storage and delivery of aviation fuel; it specified a refueling hose shall conform to American Petroleum Institute (API) Standard (STD) 1529. It could not be determined whether the supply hose connected to the re-fueling tank met API STD 1529 because of the limited information able to be collected on the hose. The FAA stated the filter connecting the supply hose to the re-fueling tank was discolored; however, the aviation fuel in the tank appeared clear.

Two fuel samples from the re-fueling tank were collected by the FAA, one sample obtained from the supply hose and another from inside the tank. The sample from the hose was pale green in color, clear and bright with no water or particulate observed. The sample from the tank was light blue in color, clear and bright with no water or particulate observed. Typical 100 low-lead aviation fuel is light blue in color. These two samples were sent to an independent laboratory for testing to evaluate the abnormal color of the fuel sample collected from the hose. Both samples collected were submitted to the laboratory in the same type of glass container. The test results determined the samples were substantially identical, with both having a high "unwashed gum" content appearing to be from different sources. The unwashed gum content in the hose sample was almost double that found in the tank sample and appeared consistent with an additive that is used in plastics and rubber hoses. The unwashed gum content in the tank was consistent with a stabilizing additive common in fuels. 

Pilot Information

Certificate: Commercial
Age: 33, Male
Airplane Rating(s): None
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter
Restraint Used: 3-point
Instrument Rating(s): Helicopter
Second Pilot Present: No
Instructor Rating(s): Helicopter; Instrument Helicopter
Toxicology Performed: No
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 05/05/2015
Occupational Pilot: Yes
Last Flight Review or Equivalent: 12/13/2014
Flight Time:  990 hours (Total, all aircraft), 717 hours (Total, this make and model), 925 hours (Pilot In Command, all aircraft), 56 hours (Last 90 days, all aircraft), 17 hours (Last 30 days, all aircraft), 6 hours (Last 24 hours, all aircraft) 

Aircraft and Owner/Operator Information

Registration: N165RV
Model/Series: R44 II II
Aircraft Category: Helicopter
Year of Manufacture: 2003
Amateur Built: No
Airworthiness Certificate: Restricted
Serial Number: 10165
Landing Gear Type: Ski;
Seats: 4
Date/Type of Last Inspection: Unknown
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time:
Engine Manufacturer: LYCOMING
Engine Model/Series: IO-540 SER
Registered Owner: MOATS JESSE R
Rated Power: 0 hp
Operator: Joshua Shiver
Operating Certificate(s) Held: Agricultural Aircraft (137)
Operator Does Business As: Prairie State Helicopters
Operator Designator Code: 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KCPS, 413 ft msl
Observation Time: 2153 UTC
Distance from Accident Site: 10 Nautical Miles
Direction from Accident Site: 18°
Lowest Cloud Condition: Clear
Temperature/Dew Point: 21°C / 8°C
Lowest Ceiling: None
Visibility: 10 Miles
Wind Speed/Gusts, Direction: 9 knots, 90°
Visibility (RVR):
Altimeter Setting: 30.3 inches Hg
Visibility (RVV):
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point:
Type of Flight Plan Filed: Unknown
Destination: Columbia, IL
Type of Clearance: Unknown
Departure Time:
Type of Airspace: Unknown 

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 38.412778, -90.223333 (est)

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