What happened
During the arrival phase, wind conditions were reported from 350 to 360 degrees at 20 knots, gusting to 25 knots. While the aircraft was landing, winds shifted slightly to 360 degrees at 21 knots. The aircraft's maximum demonstrated crosswind capability was listed as 22 knots.
The pilot reported that during the landing roll, the power levers were retarded to idle and then engaged into reverse. As the aircraft entered reverse thrust, it swerved to the left, moving away from the direction of the crosswind. The pilot then advanced the throttles out of reverse to less than flight idle. At this moment, the aircraft swerved sharply to the right.
The power levers were reversed again and brakes were applied. However, the aircraft veered off the right side of the runway. It continued into mud, causing the nose gear to collapse and both propellers to sustain damage. The pilot did not feather the engines until after both propellers had stopped turning.
The investigation
Post-accident examination revealed that the right propeller was found in the full feathered position. Removal of the right propeller dome showed no apparent abnormalities or internal damage. The left propeller, however, had evidence of having gone beyond full reverse on impact and had not feathered.
No preimpact failure was found for the primary systems. The investigation noted that the left propeller failed to feather as expected during the emergency procedure.
Findings
The accident sequence involved a combination of crosswind landing conditions and mechanical issues with the propeller system. The aircraft's ability to maintain directional control was compromised by the swerving behavior during reverse thrust application. The failure of the left propeller to feather contributed to the loss of control and subsequent runway excursion.
N12345 Piper PA-31 experienced a critical failure in the propeller feathering mechanism on the left side. The pilot reported not injured during the incident. The accident occurred during the landing phase at an airport with significant crosswind components.
The most critical factor was propeller malfunction preventing proper feathering, which exacerbated the directional control issues during the high-wind landing.