Alpine Air Cessna 421C accident
Cessna 421C · Accident: system/component malfunction/failure (non-power) during landing
From City of Colorado Springs Municipal Airport (COS) to Sterling Municipal Airport (STK)
Event
- NTSB case
- DFW08LA115
- 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
- Charter & commuter
- 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
- 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
- N513FS
- Operator
- Alpine Air
- Onboard fatalities
- Unknown
- Route
- From City of Colorado Springs Municipal Airport (COS), Colorado Springs, COTo Sterling Municipal Airport (STK), Sterling, CO
- Aircraft age
- Not recorded
- 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 135: Air Taxi & Commuter
- 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
- System/component malfunction/failure (non-power)
- 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 from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During the landing roll-out, the airline transport pilot said a 50-knot gust of wind hit the twin-engine airplane from the right side. The airplane weathervaned into the wind, at which time he applied full left rudder to compensate. The pilot tried to maintain control of the airplane as it skipped off the right side of the runway onto the grass. Subsequently, the left main gear collapsed due to the side load and the airplane came to an immediate stop. Examination of the airplane revealed that the nose gear had collapsed, the left main gear had separated from the airframe; the right main landing gear remained attached to the airframe, but the upper and lower torque links had separated, and the wheel was rotated to the right. Further examination of the upper and lower link assemblies securing bolt, bushing, two AN washers, castellated nut, and cotter pin, revealed it had pulled through the lower torque link boss, which allowed the main wheel, brake, and strut assembly to rotate inside the strut housing. In addition, both propellers were damaged and the left wing sustained substantial damage. The airplane was last inspected on March 13, 2008, at which time, the main gear camber and toe was adjusted. The failure occurred approximately 39.1 hours after this last inspection. On November 23, 1983, Cessna issued Service Kit SK 421-118, which called for the replacement of washers and for inspection of the main gear torque links. The Service Kit specified washer P/N 504518-2 to be installed under the bolt head and nut, with replacement washer P/N S1450-5H12-063 to be incorporated into the next revision to the Service Kit. Cessna issued a Service Information Letter in conjunction with the Service Kit for the purpose of "improved service life and main gear alignment retention." The washers listed in the Service Kit were not installed on the accident airplane. Compliance with the Service Kit and Service Information Letter is not mandatory.
Probable cause
Failure and separation of the upper and lower right main gear torque links links, which resulted in a loss of directional control on landing roll-out.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DFW08LA115
- Event ID
- 20080508X00629
- Case number
- DFW08LA115
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (5)
- 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: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 6f1af8ac4f28415225790c71071c234aaf47a71fb7d1c02035c41c5e0af34e6a; retrieved 2026-09-15T09:37:57.074Z.
- The NTSB's operator name is blank for N513FS; the operator shown is the name the NTSB records it doing business as.