Accident Cessna 421C N3237U,
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ASN Wikibase Occurrence # 382058
 
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Date:Friday 6 May 1983
Time:14:46 LT
Type:Silhouette image of generic C421 model; specific model in this crash may look slightly different    
Cessna 421C
Owner/operator:Kenn Aire Holding Corporation
Registration: N3237U
MSN: 421C0112
Total airframe hrs:1890 hours
Engine model:Continental GTSIO-520-L
Fatalities:Fatalities: 0 / Occupants: 6
Aircraft damage: Substantial
Category:Accident
Location:Gainesville, FL -   United States of America
Phase: Initial climb
Nature:Unknown
Departure airport:West Palm Beach, FL
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
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.

Probable Cause:

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: MIA83LA139
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB MIA83LA139

Location

Revision history:

Date/timeContributorUpdates
02-Apr-2024 09:51 ASN Update Bot Added

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