# NTSB MIA83LA139: Cessna 421C, N3237U, Gainesville, FL, May 6, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: May 6, 1983, 14:46 local (18:46 UTC)
- Place: Gainesville, FL
- Coordinates: 29.650827, -82.419532 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=29.6508&lon=-82.4195&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 6 uninjured
- Status: Completed
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 30887
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA83LA139
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/30887/pdf
- Page: https://openairdocs.org/ntsb/MIA83LA139

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, takeoff - initial climb
  - landing gear,normal retraction/extension assembly - incorrect (cause)
  - inadequate quality control, manufacturer (cause)
  - landing gear,normal retraction/extension assembly - corroded (cause)
  - landing gear,normal retraction/extension assembly - fatigue (cause)
- Nose gear collapsed, landing - roll

## Analysis

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.

## Aircraft

- Registration: N3237U (not matched to a registry record)
- Reported make and model: CESSNA 421C
- Category: Airplane
- Serial number: 421C0112
- Airframe hours: 1890
- Engines: CONTINENTAL GTSIO-520-L 375 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Kenn Aire Holding Corporation
- Airworthiness certificate: Standard, Normal
- Departed: PBI, WEST PALM BEACH, FL
- Airport: GNV, Gainesville Regional, runway 6, 4,147 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; flight instructor, flight engineer, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 24,400 total, 1,220 in this make and model, 23,800 as pilot in command, 55 in the last 90 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 82 °F, dew point 45 °F
- Altimeter: 30.00 inHg
- Observed at: GNV

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19830506020819A](https://openairdocs.org/incident/19830506020819A), May 6, 1983: Cessna 421C, Gainesville, FL, Substantial damage. Nose wheel collapsed during landing. Rod end pn MS21242S4K failed. High stress fatigue cracking found.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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