MIA83LA139 · Cessna 421C
Cessna 421C · Accident: airframe, component or system failure during initial climb
From PBI · West Palm Beach, FL to an unrecorded destination
Event
- NTSB case
- MIA83LA139
- 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
- 0
- 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
- N3237U
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From PBI · West Palm Beach, FLTo not recorded
- 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
- Initial climb
- First occurrenceThe 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
- Airframe, component or system failure
- 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
- Landing gear, normal retraction/extension assembly › Corroded
- Landing gear, normal retraction/extension assembly › Fatigue
- Landing gear, normal retraction/extension assembly › Incorrect
- Manufacturer › Inadequate quality control
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
DURING TAKEOFF, THE AIRCREW HEARD AN UNUSUAL 'THUD' SOUND AS THE GEAR WAS RETRACTING, BUT ALL GEAR INDICATIONS WERE NORMAL. PRIOR TO LANDING AT THE DESTINATION, 3 GREEN LIGHTS WERE OBSERVED WHEN THE LANDING GEAR SWITCH WAS MOVED TO EXTEND THE GEAR. A NORMAL TOUCHDOWN WAS MADE, BUT WHEN THE NOSE WAS LOWER, THE ACFT SETTLED ON ITS NOSE. AN INVESTIGATION REVEALED THAT THE ROD END, PN MS21242S4K, WHICH CONNECTS THE NOSE GEAR TO THE NOSE GEAR ACTUATOR, HAD FAILED. A METALLURGICAL EXAM REVEALED SIGNS OF HIGH STRESS FATIGUE CRACKING OVER 1/2 OF THE FRACTURE SURFACE. THE FATIGUE ORIGINATED IN THE CURVE OF A THREAD RUNOUT THAT WAS CORRODED. THE RADIUS OF THE CURVED SURFACE MEASURED 0.056 INCH. THE SPECIFICATION, MS-21242, REQUIRED A MINIMUM RADIUS OF 0.063 INCH. SINCE THE DOWN POSITION SWITCH WAS CONNECTED THE ACTUATOR, IT HAD INDICATED A SAFE INDICATION WHEN THE ACTUATOR HAD OPERATED TO THE EXTENDED POSITION. HOWEVER, WITH THE ROD END FAILURE, THE NOSE GEAR WAS HANGING IN AN LOCKED POSITION.
Verbatim NTSB analysis from the NTSB dataset
Sources
NTSB record MIA83LA139
- Event ID
- 20001214X43083
- Case number
- MIA83LA139
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: investigation status. 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: d42f7a2187dc960f9053996601aed8680f3d2f66bd0c67257a347ebc27ae9449; retrieved 2026-09-18T20:59:32.736Z.