What happened
The accident occurred while the aircraft was conducting an approach to land. According to the pilot's account, he advanced the power lever to increase thrust during the final phase of the approach. At this moment, he perceived that the propeller had unexpectedly entered the beta range. This anomaly was attributed to excessive play within the propeller control linkage.
Approximately 50 feet above ground level and about 200 feet from the runway threshold, the aircraft lost sufficient lift and stalled. The aircraft then fell directly to the ground, resulting in a crash landing short of the intended runway.
The investigation
The primary mechanical factor identified during the review of the event was the condition of the propeller control system. The pilot reported that play in the propeller control linkage allowed the propeller to shift into the beta range without intentional input from the flight controls. This unintended shift in propeller pitch likely caused a significant and sudden loss of thrust, contributing directly to the stall.
Findings
The sequence of events indicates a critical failure in maintaining adequate airspeed and altitude during the approach. The unexpected entry into beta range reduced available thrust at a low altitude where recovery options were severely limited. The proximity to the ground (50 feet AGL) left insufficient time or altitude for the pilot to regain control or execute a go-around maneuver effectively.
The investigation highlights the importance of mechanical integrity in propeller control systems. Excessive play in linkages can lead to unpredictable engine performance characteristics, particularly during critical phases of flight such as takeoff and landing where power adjustments are frequent.