# NTSB FTW99TA194: Bell 47G-3B-1, N4002G, Sour Lake, TX, July 17, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: July 17, 1999, 16:30 local (21:30 UTC) - Place: Sour Lake, TX - Coordinates: 30.130115, -94.400825 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.1301&lon=-94.4008&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 30, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46855 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW99TA194 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46855/pdf - Page: https://openairdocs.org/ntsb/FTW99TA194 ## Probable cause The pilot's failure to adequately preflight the helicopter's fuel system resulting in the total loss of engine power as a result of water contamination. Factors were the incorrect filter installed on the fueling truck and the pilot's improper touchdown technique. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - nonmechanical, takeoff - initial climb - airport facilities,refueling truck/equipment - other (contributing factor) - aircraft preflight - inadequate, pilot in command (cause) - fuel system,tank - contamination,water (cause) - Forced landing, descent - emergency - autorotation - initiated, pilot in command - Hard landing, emergency landing after takeoff - touchdown - improper, pilot in command (contributing factor) - misc rotorcraft,tail boom - separation ## Analysis The helicopter lost engine power during takeoff due to contaminated fuel. The commercial helicopter pilot stated that the night before the accident flight, the fueling truck, which contained three tanks (one each for water, chemicals, and fuel), was checked. The pilot stated that the fuel appeared 'normal' that night. The following day, prior to the accident flight, the helicopter was 'refueled without sumping the tanks.' The pilot added that during takeoff, the engine lost power about 50 feet above the ground, at 30 miles per hour. He executed an autorotation to the ground where the main rotor blades impacted the tail boom and the tail rotor blades contacted the ground. The pilot stated that he found 20 gallons of water in the helicopter's fuel tank after the accident. He added that he discovered the fuel truck had a crack in between the water and fuel tanks. Approximately 80 gallons of water had leaked into the truck's fuel tank. The fuel truck was 'supposed to have an aqua stop filter installed that will not pump if water is present but the wrong filter was installed.' ## Factual narrative On July 17, 1999, at 1630 central daylight time, a Bell 47G-3B-1 agricultural helicopter, N4002G, was substantially damaged during a forced landing following a loss of power during takeoff climb near Sour Lake, Texas. The commercial helicopter pilot, sole occupant, was not injured. The helicopter was owned and operated by Precision Air Services, Inc., of Selma, Alabama. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The helicopter was departing for a local flight at the time of the accident. During a telephone interview conducted by the NTSB investigator-in-charge, the pilot reported that the night before the accident flight, he checked the fueling truck, which contained three tanks: one each for water, chemicals, and fuel. The pilot stated that the fuel appeared "normal" that night. The following day, prior to the accident flight, the helicopter was "refueled without sumping the tanks." The pilot stated that during takeoff, the engine lost power about 50 feet above the ground, at 30 miles per hour. He executed an autorotation to the ground where the main rotor blades impacted the tail boom and the tail rotor blades contacted the ground. The pilot reported that the main rotor blades were damaged, the tail rotor blades were "destroyed", and the tail boom was severed. The pilot added that he found about "20 gallons of water in the helicopter's fuel tank" after the accident. The pilot examined the truck's tanks and found a crack between the water and fuel tanks. The pilot estimated that "80 gallons of water had leaked into the truck's fuel tank." In the enclosed Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot added that the fueling truck was supposed to have an "aqua stop filter installed that will not pump if water is present but the wrong filter was installed." ## Aircraft - Registration: [N4002G](https://openairdocs.org/deregistered/N4002G-2018-03-23), registration cancelled 2018-03-23, S/N 6529, built 1966 (OpenAirDocs) - Reported make and model: Bell 47G-3B-1 - Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs) - Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 6529 - Airframe hours: 10013 - Engines: Allison T63-A700 317 horsepower turbo shaft - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Precision Air Services, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 20, 1999, 155 hours before - Departed: NONE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; commercial, flight instructor; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 11,549 total, 500 in this make and model, 11,349 as pilot in command, 170 in the last 90 days, 85 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 75 °F - Observed at: BPT, 22 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19990717035079A](https://openairdocs.org/incident/19990717035079A), Jul 17, 1999: Bell 47G3B1, Sour Lake, TX, Substantial damage. (.4) The helicopter lost engine power during takeoff due to contaminated fuel. The commercial helicopter pilot stated that the night before the accident… ## Other investigations on N4002G (4) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ERA15LA296](https://openairdocs.org/ntsb/ERA15LA296), Aug 3, 2015: Bell 47G 3B 1 (N4002G), Camden, AL, substantial damage. Probable cause: A failure of the helicopter's hydraulic flight control systems for reasons that could not be determined due to the fire damage, and the pilot's inability to turn off the hydraulic system to relieve… - [NTSB ATL03LA007](https://openairdocs.org/ntsb/ATL03LA007), Oct 19, 2002: Bell 47G3B1 (N4002G), Highfalls, GA, substantial damage. Probable cause: The pilots inadequate fuel management, and subsequent loss of engine power due to fuel exhaustion, and a in-flight collision with trees during an autorotation. A factor was the pilot's failure to… - [NTSB FTW79FRG13](https://openairdocs.org/ntsb/FTW79FRG13), Jan 20, 1979: Bell 47G-4A (N4002G), Falfurrias, TX, destroyed - [NTSB UNK71X0109](https://openairdocs.org/ntsb/UNK71X0109), Jun 8, 1971: Bell 47G-4A (N4002G), Angola, Angola, substantial damage From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.