On October 2, 2007, a Cessna 172N (registration N6291D) operated by Georg Domogala was involved in an aviation accident near Green Valley, AZ. Investigators recorded the probable cause as: The number three cylinder exhaust rocker arm hold down nut backed off, causing the rocker arm to disconnect from the cylinder. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
During cruise, an engine ran rough and backfired. The pilot performed a precautionary landing on a road, during which the aircraft struck road signs and a fence, damaging both wings. Examination found a rocker arm nut had backed off.
Event Summary
During cruise flight, the aircraft experienced a sudden onset of engine roughness accompanied by intermittent backfiring. The pilot attempted to diagnose the issue but was unable to resolve it. Consequently, the pilot elected to perform a precautionary landing on a nearby road.
During the landing roll, the airplane collided with two road signs and a barbwire fence. The impacts resulted in substantial damage to both the left and right wings.
Engine Examination
A post-incident examination of the engine was conducted. The inspection revealed that the number three cylinder exhaust rocker arm had become disconnected from the cylinder. The disconnection was traced to the rocker arm hold down nut having backed off, allowing the rocker arm to separate.
Probable cause
The number three cylinder exhaust rocker arm hold down nut backed off, causing the rocker arm to disconnect from the cylinder.
What happened in the 2 Oct 2007 Cessna 172N accident near Green Valley, AZ?
During cruise, an engine ran rough and backfired. The pilot performed a precautionary landing on a road, during which the aircraft struck road signs and a fence, damaging both wings. Examination found a rocker arm nut had backed off.
What aircraft was involved and where did it happen?
The accident on 2 Oct 2007 involved a Cessna 172N, registration N6291D, operated by Georg Domogala, at Green Valley, AZ.
What was the probable cause of the accident?
The number three cylinder exhaust rocker arm hold down nut backed off, causing the rocker arm to disconnect from the cylinder.
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