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ASN Wikibase Occurrence # 44922
Last updated: 15 February 2020
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Type:Silhouette image of generic C170 model; specific model in this crash may look slightly different
Cessna 170
Registration: N2534V
C/n / msn: 18038
Fatalities:Fatalities: 2 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Herron, WA -   United States of America
Phase: En route
Departure airport:Sequim, WA (2WA1)
Destination airport:Auburn, WA (S50)
Investigating agency: NTSB
The airplane was en route when according to the last nine minutes of radar data, the airplane descended from 3,400 to 300 feet. Sixteen days after the aircraft was reported missing Search and Rescue personnel located the airplane in a water inlet at a depth of 132 feet; 19 days later the aircraft was recovered from the accident site. A postaccident examination of the engine and the airframe revealed that the left exhaust muffler had separated at the forward seam, with evidence of sooting noted on the scat hoses surrounding the area. It was also observed that the forward end cap and exhaust riser were separated from the main body of the muffler. Magnified examinations found that almost all of the fractures were blackened and severely oxidized. The failure of the muffler was the result of undetected oxidation and cracking resulting from normal thermal degradation. The cracking would have allowed exhaust gases direct access to cabin air through the heater system. Toxicological testing of the pilot and his passenger revealed carbon monoxide levels of 45 percent and 46 percent, respectively.

Probable Cause: The failure of the left muffler while maneuvering, resulting in a carbon monoxide leak into the cabin rendering the pilot incapacitated, and the subsequent uncontrolled descent and impact with water.



Revision history:

28-Oct-2008 00:45 ASN archive Added
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
07-Dec-2017 17:43 ASN Update Bot Updated [Operator, Source, Narrative]

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