NTSB CAROL · Event
Event ATL94GA148
Aircraft involved
Probable cause & findings
The loss of engine power for undetermined reasons.
Factual narrative
HISTORY OF FLIGHT
On July 30, 1994, at 1500 eastern daylight time, a Hughes TH55-A, N789MC was substantially damaged following a collision with a tree during an emergency landing attempt near Savannah, Georgia. The commercial pilot received minor injuries in the accident. The aircraft was being operated under the provisions of 14 CFR Part 91 by the Chatham County Mosquito Control. Visual meteorological conditions existed at the time, and no flight plan had been filed for the aerial application flight. The pilot stated that during a repositioning flight to dispense mosquito control chemicals, the aircraft engine stopped producing power. He attempted an emergency landing in a wooded swamp area. The aircraft came to rest in the top of a large oak tree.
PERSONNEL INFORMATION
The pilot held a commercial pilot certificate, with airplane single and multiengine, helicopter, and instrument airplane and helicopter ratings. He had a current second class medical at the time of the accident. The pilot had accumulated approximately 300 hours of flight experience in the Hughes TH55-A helicopter. Additional personnel information may be obtained in this report on page 3 under section titled Pilot Information.
AIRCRAFT INFORMATION
The Hughes TH55-A helicopter is a two place utility helicopter. The aircraft was originally designed as a training aircraft for military operations. This aircraft had been purchased from the military and modified with spray equipment, for the purpose of dispensing chemicals to control mosquitos. Additional aircraft information may be obtained in this report on page 2 under section titled Aircraft Information.
METEOROLOGICAL INFORMATION
Meteorological information may be obtained in this report on page 3 under section titled Weather Information.
WRECKAGE AND IMPACT INFORMATION
The aircraft came to rest in the top of a tall oak tree. All three main rotor blades showed signs of chordwise compression buckling along the leading edges. The tail boom was separated from the fuselage at the attach point. The right side of the fuselage had extensive impact damage, and the cockpit canopy was fractured and separated from the aircraft. The aircraft fuel tank was intact, and had approximately ten gallons of fuel remaining in the tank. All transmission belts were in place, and showed no signs of excessive wear. The electric clutch engagement solenoid was checked, and operation was normal. The electric fuel pump was tested and found to operate normally. There was continuity of the aircraft controls from the cyclic and collective through the swash plate and into the main rotor head. All fractures of the tail rotor cables were consistent with tensile overload failure. Examination of the aircraft engine revealed that the aircraft fuel injector had been damaged during the impact, and operational testing of the unit was not possible. The unit was disassembled, and an inspection of the diaphragm revealed that the rubber diaphragm was pliable, and there were no holes in the diaphragm. There was continuity of the engine drive train, and the compression of the cylinders was within the normal limits. The aircraft timing was checked, and the timing was set in accordance with the maintenance manual requirements. An examination of the aircraft spark plugs revealed that the plugs were dark black in color, and had heavy carbon sooting.
ADDITIONAL INFORMATION
This investigation was conducted at the request of the Chatham County Mosquito Control. The aircraft had been removed from the accident site, and was in the Chatham County Mosquito Control Hangar at the time of the examination. THE PILOT STATED THAT HE HAD JUST COMPLETED DISPENSING A LOAD OF CHEMICAL USED TO CONTROL MOSQUITO'S. WHILE ON A REPOSITION FLIGHT TO DISPENSE ANOTHER LOAD OF CHEMICAL, THE AIRCRAFT ENGINE STOPPED PRODUCING POWER. AN EMERGENCY AUTOROTATION WAS ACCOMPLISHED INTO A WOODED AREA. THE AIRCRAFT CAME TO REST IN THE TOP OF A TALL OAK TREE. THE PILOT EXITED THE AIRCRAFT THROUGH THE WINDSHIELD AND MANAGED TO CLIMB DOWN OUT OF THE TREE. THE PILOT ESTIMATED THAT HE HAD APPROXIMATELY 25 GALLONS OF FUEL ON BOARD THE AIRCRAFT AT THE TIME OF THE ACCIDENT. EXAMINATION OF THE AIRCRAFT ENGINE REVEALED THAT THERE WAS CONTINUITY OF THE ENGINE DRIVE CHAIN, AND THE CYLINDER COMPRESSION WAS WITHIN ACCEPTABLE LIMITS. THE AIRCRAFT SPARK PLUGS WERE BLACK AND SOOTED. THERE WAS FUEL IN THE LINES AND IN THE AIRCRAFT FUEL INJECTOR. THE AIRCRAFT FUEL INJECTOR WAS DAMAGED IN THE ACCIDENT, AND COULD NOT BE TESTED FOR OPERATION. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1994_ATL94GA148.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (maintenance). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- Embry-Riddle Scholarly Commons 2026 · Journal article (IJAAA)
From Reactive to Predictive: A hybrid Trust-Mediated Adoption Framework for Data-Driven Maintenance in Distributed-Authority Aviation Environments
Modern aviation maintenance operates within increasingly data-intensive technological environments, yet the operational integration of predictive maintenance into routine decision-making remains incon…
- Semantic Scholar 2025 · Article (Applied Sciences)
Decision-Making Framework for Aviation Safety in Predictive Maintenance Strategies
The implementation of predictive maintenance (PM) in aviation presents unique challenges due to strict safety requirements, complex operational environments, and regulatory constraints.
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
Low-Resource Automatic Speech Recognition Domain Adaptation – A Case-Study in Aviation Maintenance
With timeliness and efficiency being critical in the aviation maintenance industry, the need has been growing for smart technological solutions that optimize and streamline the different underlying ta…
- Embry-Riddle Scholarly Commons 2024 · Journal article (JAAER)
A New Trajectory in UAV Safety: Leveraging Reinforcement Learning for Distance Maintenance Under Wind Variations
In the field of aviation, safety is a critical cornerstone, and the operation of Unmanned Aerial Vehicle (UAV) systems is deeply connected with this principle.
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
Just Culture in Aviation: A Metaphorical Study on Aircraft Maintenance Students
Just Culture, a sub-dimension of safety culture, has been a prominent and debated topic in aviation safety in recent years.
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
Performance PRISM: A Comprehensive Framework For Performance Measurement In Aircraft Maintenance
Aircraft maintenance is governed by rigorous safety requirements and high operational complexity, demanding robust performance measurement frameworks to ensure optimal maintenance practices.
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