On September 23, 1991, a Cessna 177 (registration N3314T) operated by Sigmet Inc. was involved in an aviation accident near Snohomish, WA. Investigators recorded the probable cause as: THE SEPARATION OF THE MIXTURE CONTROL CABLE (CORE) RESULTING FROM SEPARATION OF THE ADEL CLAMP ASSEMBLY AND IMPROPER ADJUSTMENT BY MAINTENANCE PERSONNEL. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A partial power loss during cruise forced the pilot to execute a landing on rough terrain. Post-crash examination showed separation of the mixture control cable core and its retaining Adel clamp. The nose wheel assembly collapsed during the landing rollout.
Incident Description
During cruise flight, the pilot experienced a partial loss of engine power. Unable to reach a suitable airport, the pilot executed a forced landing on rough terrain. During the landing rollout, the nose wheel assembly collapsed.
Post-Crash Examination
Examination after the event revealed that the mixture control cable core had separated at the mixture control arm bolt adjacent to the carburetor. The Adel clamp assembly that retained the mixture control cable near the mixture control arm was also observed to be separated. The separated cable core was due to reverse bending fatigue cracking consistent with excessive vibratory loads applied to the cable as a result of the separated Adel clamp assembly. The separated Adel clamp was due to excessive twisting loads applied to the clamp.
Forced Landing Outcome
The forced landing was executed on rough terrain. During the rollout, the nose wheel assembly collapsed.
Frequently asked questions
What happened in the 23 Sept 1991 Cessna 177 accident near Snohomish, WA?
A partial power loss during cruise forced the pilot to execute a landing on rough terrain. Post-crash examination showed separation of the mixture control cable core and its retaining Adel clamp. The nose wheel assembly collapsed during the landing rollout.
What aircraft was involved and where did it happen?
The accident on 23 Sept 1991 involved a Cessna 177, registration N3314T, operated by Sigmet Inc., at Snohomish, WA.
What was the probable cause of the accident?
THE SEPARATION OF THE MIXTURE CONTROL CABLE (CORE) RESULTING FROM SEPARATION OF THE ADEL CLAMP ASSEMBLY AND IMPROPER ADJUSTMENT BY MAINTENANCE PERSONNEL.
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