NTSB CAROL · Event
Event FTW91LA064
Aircraft involved
Probable cause & findings
THE INITIAL RESTRICTED MOVEMENT AND EVENTUAL LOCKING OF THE CYCLIC CONTROL AS A RESULT OF THE FAILURE OF THE LATERAL SERVO. A FACTOR WAS THE INSTALLATION OF THE FAILED COMPONENT BY AN UNQUALIFIED PERSON.
Factual narrative
A COMMERCIAL PILOT WAS MANEUVERING A HELICOPTER TO CONTROL A HERD OF CATTLE. THE PILOT NOTICED AN INTERMITTENT BINDING IN THE LEFT QUADRANT OF THE CYCLIC CONTROL. HE NOTIFIED HIS FLIGHT LEADER OF HIS INTENTIONS TO LAND AND INSPECT THE HYDRAULIC SERVOS IN THE FLIGHT CONTROL SYSTEM, AND INITIATED A PRECAUTIONARY LANDING CLOSE TO THEIR MAINTENANCE SUPPORT VEHICLE. DURING THE LANDING FLARE, THE HELICOPTER PITCHED SHARPLY TO THE RIGHT REAR AS THE LATERAL CYCLIC CONTROL BECAME LOCKED. THE PILOT APPLIED FULL RIGHT PEDAL TO TRY TO CUSHION THE LANDING AND PREVENT THE HELICOPTER FROM ROLLING. THE HELICOPTER WAS DESTROYED UPON IMPACT WITH THE MESQUITE TREES. THE FAILED LATERAL SERVO HAD BEEN REPLACED BY AN UNQUALIFIED PERSON PRIOR TO THIS FLIGHT. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1991_FTW91LA064.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 (stall, 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 2023 · Conference paper
The Value of Strong Partnerships to Build a Successful Aviation Maintenance Career Pathway Program for Transitioning Military Service Members
The aerospace industry is competing with other industries for a qualified workforce, and many of those competing industries are investing heavily in creating workforce development pipelines.
- 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…
- NASA NTRS 2026 · Conference Paper
Computational Analysis of Steady State Aerodynamics of Transonic Truss-Braced Wing Configuration in Deep Stall
This study presents a computational investigation of steady state aerodynamics of the Subsonic Ultra-Green Aircraft Research (SUGAR) Transonic Truss-Braced Wing (TTBW) configuration over a wide range …
- 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.
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