WPR17LA051 · Cessna 421C C
Cessna 421C C · Accident: landing gear collapse
From Palo Alto Airport (PAO) to Westover Field Amador County Airport (JAQ)
Event
- NTSB case
- WPR17LA051
- 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
- API-reported fatalities
- 0 · all aircraft and ground
- 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
Cessna 421C C
- Aircraft type
- Cessna 421
- 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
- N71RC
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Palo Alto Airport (PAO), Palo Alto, CATo Westover Field Amador County Airport (JAQ), Jackson, CA
- Aircraft age
- About 40 years (built 1977)
- 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
- Landing gear collapse
- 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 systems
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The airline transport pilot reported that, during the landing roll at the end of a cross-country flight, when he attempted to lightly apply the brakes, the airplane began to yaw from side to side. The airplane subsequently exited the right side of the runway and sustained substantial damage to the right wing spar. During the landing, the right main landing gear collapsed. An on-site examination revealed that the right main landing gear torque link assembly had separated at the hinge attach point due to the failure of the torque link bolt. Although the bolt was located at the accident site, the bolt's nut, cotter pin, and washer were missing. Further examination revealed that the torque link bolt threads had been rounded over and exhibited remnants of material consistent with the threads of the mating nut. In addition, remnants of the cotter pin that was installed through the bolt hole were visible. The sheared cotter pin and threads from the nut that remained within the bolt threads suggest that the torque link bolt/nut assembly was overloaded, which resulted in the landing gear collapse.
A Federal Aviation Administration special airworthiness information bulletin had been issued about 3 years before the accident to advise owners, operators, and maintenance technicians of the make and model airplane of the need to inspect the main landing gear torque link assembly to ensure the correct thickness of washers and to ensure that the washers are installed properly, and a Cessna service bulletin had also been issued previously regarding the washers. However, no maintenance records were available to determine the airplane's maintenance history or compliance with the applicable bulletins.
Probable cause
The failure of the right main landing gear torque link bolt in overstress, which resulted in the collapse of the landing gear during the landing roll.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR17LA051
- Event ID
- 20170109X24157
- Case number
- WPR17LA051
- 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. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2017-01-07.
- API snapshot SHA-256: cd6ae7f3a78d84e8e64dd11e4818857e90b0f751392b01b709df326677e3f9b1; retrieved 2026-09-16T04:56:13.324Z.