Pilot Debrief

Sonex WAIEX B near Laveen Village, AZ — 2021-11-15

Final reportWPR22LA035
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Date
2021-11-15
Location
Laveen Village, AZ, USA
Airport
AZ90
Aircraft
Sonex WAIEX B
Registration
N535D
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Cruise

Probable cause

Failure of the rocker swivel assembly due to either wear or corrosion, which resulted in a loss of engine power.

NTSB narrative

The pilot reported the engine began running rough during cruise flight, and the airplane could not maintain altitude. The pilot initiated a forced landing to an airstrip and during the descent realized that he was not going to make the airstrip, so he elected to landed on the desert terrain. The airplane impacted rocks and a barbed wire fence which caused the airplane to nose over, which resulted in substantial damage to the wings, stabilizers, and ruddervators. Postaccident examination of the engine revealed that the No. 4 exhaust rocker assembly swivel housing separated from the screw body, likely due to wear of the swivel and the swivel pad housing. This wear likely occurred because of either incorrect spacing between the pad and valve, or corrosion.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have landed at the airstrip before realizing he couldn't make it.

NTSB coding

Evidence available

  • 4 docket documents
View NTSB final reportView NTSB docket

Docket documents4

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