WPR21LA135 · Aviat Aircraft Inc A-1C-200
Glasair III Investors Aviat Aircraft Inc A-1C-200 · Accident: loss of control on ground during landing
From Double Eagle II Airport (AEG) to an unrecorded destination
Event
- NTSB case
- WPR21LA135
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- Unknown
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Aviat Aircraft Inc A-1C-200
- Aircraft type
- Aviat A-1
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N43LL
- Operator
- Glasair III Investors
- Onboard fatalities
- Unknown
- Route
- From Double Eagle II Airport (AEG), Albuquerque, NMTo not recorded
- Aircraft age
- About 3 years (built 2018)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Landing · landing roll
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control on ground
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Aircraft › Aircraft systems
- Aircraft › Fluids/miscellaneous hardware
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that, during the approach to land, he disconnected the autopilot, and the airplane immediately yawed to the right. The pilot applied left pedal, engaged the yaw damper, and continued the approach. He subsequently disengaged the yaw damper and entered a cross-control slip to descend, and he was unable to make an effective left rudder input. The airplane touched down on the gravel runway surface and veered to the right. The airplane then crossed over to the asphalt runway surface and subsequently ground-looped. The airplane’s autopilot had been installed in the airplane 7 weeks before the accident. Postaccident examination of the airframe revealed that the autopilot hardware installation was substandard. Specifically, the guard pin, which was designed to prevent the bridle cable from traveling out of the pulley’s groove past the sheaves, was not installed to the yaw servo tray and the right pulley assembly, which allowed the yaw servo bridle cable to separate from the pulley’s phenolic sheave. Additionally, the bridle cable, which was undertensioned, became trapped between the yaw servo pulley and the attachment tray and prohibited the pilot from applying left rudder. As a result, the pilot was unable to maintain directional control during the landing roll. The guard pin is designed to prohibit the bridle cable from being able to travel out of the pulley’s groove past the sheaves.
Probable cause
The substandard installation of the airplane’s autopilot system hardware, which resulted in a malfunction of the rudder control system during flight and a loss of directional control during the landing roll.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR21LA135
- Event ID
- 20210317102778
- Case number
- WPR21LA135
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2021-02-19.
- API snapshot SHA-256: c2355da60da749c05ebe3a300b5026d875037177ed72105c301a2dc2cd220d85; retrieved 2026-09-16T13:50:40.846Z.