What happened
During an aerial topdressing mission, a DHC-2 Beaver experienced a catastrophic loss of control while performing a maneuver. The aircraft was engaged in routine agricultural procedures, specifically executing a turn that involved significant aerodynamic loads. During this phase of flight, the vertical stabilizer's attachment bolts failed, causing the fin and rudder to rotate approximately 90 degrees. This structural failure resulted in the components resting horizontally against the elevator and tailplane.
As a result of the sudden loss of directional and vertical stability, the pilot was unable to maintain control of the aircraft at such a low altitude. The plane impacted a field, leading to the death of the pilot, who was the only person on board. The impact caused the total destruction of the airframe, rendering it a write-off.
Findings
The investigation determined that the primary cause of the accident was the failure of the bolts securing the fin to the fuselage. This mechanical failure stripped the aircraft of its ability to maintain stable flight during high-G maneuvers. The investigation highlighted that while the aircraft type is designed for rugged utility, the intense stresses of frequent agricultural operations and heavy loading from unpaved airstrips contributed to the degradation of the hardware.
Following the accident, a fleet-wide inspection was mandated for all similar aircraft. This inspection uncovered several instances of worn or cracked attachment bolts in other units. Consequently, an Airworthiness Directive was issued, grounding all DHC-2 Beaver aircraft until comprehensive inspections and bolt replacements could be performed to ensure structural integrity.