What happened
Shortly after passing the Watson Intersection while inbound to Tucson, Arizona, the outboard tip of one propeller blade separated from the aircraft. Upon detecting the failure, the pilot immediately turned the magneto switch off and slowed the aircraft until the propeller stopped rotating completely. The pilot then executed an emergency landing short of the airport, touching down in a hard-packed dirt area.
The investigation
A metallurgical examination was conducted on the remaining blade stub attached to the hub. The analysis revealed that the failure originated from fatigue, indicating a progressive structural breakdown rather than an immediate catastrophic overload at the moment of separation.
Findings
The primary mechanical issue was identified as fatigue failure of the propeller blade. The pilot's decision to shut down the engine and perform a controlled emergency landing in a suitable dirt area allowed for a safe outcome despite the significant mechanical failure.