Accident Cessna U206 N4661Z,
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ASN Wikibase Occurrence # 381341
 
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Date:Sunday 24 July 1983
Time:21:30 LT
Type:Silhouette image of generic C206 model; specific model in this crash may look slightly different    
Cessna U206
Owner/operator:Rust's Flying Service
Registration: N4661Z
MSN:
Engine model:Lycoming O-320
Fatalities:Fatalities: 0 / Occupants: 0
Aircraft damage: Unknown
Category:Accident
Location:Near Iliamna, AK -   United States of America
Phase:
Nature:Unknown
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE ENG LOST POWER JUST AFTER A WATER TAKEOFF. THE ACFT LANDED STRAIGHT AHEAD IN MUSKEG & TUNDRA COLLAPSING THE FLOATS. ENG TEARDOWN REVEALED A METALLIC 'NUGGET' IN THE LEFT INTAKE MANIFOLD BETWEEN THE #4 & #6 PORTS. NUMEROUS MARKS WERE FOUND ON THE INSIDE OF BOTH INTAKE MANIFOLDS. THERE WAS MINOR DENTING, SCRATCHING & PEENING ON THE INTERIOR OF THE 90 DEG ELBOWS FROM BOTH ENDS OF THE CROSSOVER TUBE, INTAKE VALVE PORTS, SEATS & VALVE FACES OF CYLS 4,5 & 6. THE NUGGET WAS COMPOSED OF THE SAME MATERIAL AS THE AIRBOX ASS'Y, CESSNA P/N 1250705, WHICH CONTAINED TWO HOLES APRX 2-1/2 SQUARE INCHES EACH IN THE AIRBOX WALL. THE HOLES WERE CAUSED BY FATIGUE CRACKS. THE SOURCE OF LOADING CAUSING THE FATIGUE CRACKPROPAGATION WAS DUE TO MEMBRANE &/OR BENDING LOADS IN THE AIRBOX WALL CAUSED BY OUT-OF-PLANE DEFORMATION. THESE DEFORMATION WERE MOST LIKELY CAUSED BY EXCITING A NATURAL MODE OF VIBRATION IN THE WALL. THREE DUCT FAILURES WERE REPORTED TO THE FAA IN 1983, TWO OF WHICH WERE IN C-210 ACFT.

Probable Cause:

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ANC83FA131
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB ANC83FA131

Revision history:

Date/timeContributorUpdates
02-Apr-2024 02:23 ASN Update Bot Added

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