NTSB CAROL · Event
Event DEN99LA162
Aircraft involved
Probable cause & findings
The pilot's inadvertent ground loop during landing roll. Factors were the malfunctioning self centering locking device on the tail wheel, the right rear quartering tail wind, and the 3 to 4 inch high berm along the edge of the runway.
Factual narrative
On September 14, 1999, at 1200 mountain daylight time, a Piper PA-22-135 (converted to a PA-20-135, Pacer), N3329A, was substantially damaged during landing rollout at Weld County Airport, Greeley, Colorado. The airline transport pilot and his passenger were not injured. The aircraft was being operated by the owner under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal cross-country flight which originated from Larned, Kansas, approximately 2 hours, 25 minutes before the accident. No flight plan had been filed. The pilot reported that when he was 10 miles east of the airport he heard that the wind was 100 degrees at 6 knots, and that the active runway was 35 (runway 27-09 was closed, and runway 03-21 was a dirt runway in unknown condition). He flew over the airport and entered the traffic pattern on a left downwind. The pilot said the landing appeared normal until about 40 to 45 knots when the airplane began drifting to the left of centerline. He said he corrected the airplane back to the centerline, and then it suddenly ground looped to the right. The pilot said that there was a 3 to 4 inch high dirt berm along the side of the runway. He said his left main landing gear and tail wheel impacted the berm, and folded under the airplane. Subsequently, the left wing spar broke at the mid point, and the empennage was twisted 90 degrees. He further stated that the rubber skid marks on the runway indicated that the tail wheel was oscillating, or shimmying (see pilot's statement). The maintenance person, who recovered the airplane, said that the self-centering tail wheel locking device was "well lubricated," which is what the maintenance manual requires. He said aerial application pilots who fly airplanes with similar tail wheel self-centering devices always instruct him not to lubricate their self-centering devices when he performs maintenance on their aircraft. They told him that it was easier to land in a crosswind when their tail wheel self-centering devices were dry. The pilot said that he was landing on runway 35 with a right quartering tailwind of 6 knots. The landing appeared normal until about 40 to 45 knots when the airplane began drifting to the left of centerline. He said that he corrected the airplane back to the centerline, and then it suddenly ground looped to the right. The pilot said that there was a 3 to 4 inch high dirt berm along the side of the runway. He said that when his left main landing gear and tail wheel impacted this berm, they folded under the airplane. He further stated that the rubber skid marks on the runway indicated that the tail wheel was oscillating, or shimmying. The maintenance person who recovered the airplane said that the self-centering tail wheel locking device was 'well lubricated,' which is what the maintenance manual calls for. He said the aerial application pilots that fly airplanes with similar tail wheel self-centering devices always instruct him not to lubricate their self-centering devices when he performs maintenance on their aircraft. They told him that it was easier to land in a crosswind when their tail wheel self-centering devices were dry. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1999_DEN99LA162.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
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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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