Pilot Debrief

CIRRUS DESIGN CORP SF50 near Spearfish, SD — 2025-01-04

Final reportCEN25LA069
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Date
2025-01-04
Location
Spearfish, SD, USA
Airport
SPF
Aircraft
CIRRUS DESIGN CORP SF50
Registration
N603AP
Category
Airplane
Highest injury
None
Fatalities
0

Probable cause

The pilot’s failure to land on the centerline of the snow-covered runway at night, which resulted in the left wing impacting a snowbank, a subsequent loss of directional control, and runway excursion.

NTSB narrative

The pilot reported the flight proceeded uneventfully until landing. The air traffic controller advised that the runway was covered with 1/8” of wet snow and braking action was reported as good. The pilot noted the airport was in sight about 4 miles out, and he executed a straight-in approach to runway 13. He verified that the landing gear was down. His intention was to touchdown at the landing reference speed (Vref) to minimize the need for braking. The airplane was lined up with the extended runway centerline and the pilot disconnected the autopilot about 2 miles from the runway. The pilot recalled that during landing, about 8 to 10 feet above ground level (agl), he received an aerodynamic stall warning with the stick shaker. At first, the touchdown seemed normal, but then the airplane started to drift to the left. The pilot’s efforts to maintain directional control were not successful. The airplane “lurched hard” when it impacted the snowbank along the left side of the runway. When the airplane came to rest, the pilot shut down the engine, and the airplane was evacuated. One of the passengers confirmed 3-green landing gear down lights while on approach. The airplane appeared to be slightly left of the runway centerline and quickly drifted to the left after it touched down. When left wing caught the snowbank the airplane departed the left side of the runway. The wind was almost calm when the passenger exited the airplane. Another passenger estimated about 2 to 3 inches of snow was covering the runway when they evacuated the airplane. An examination of the accident site revealed runway wheel marks (compressed snow) corresponding to the airplane beginning about 150 ft before the touchdown zone (1,000-ft) markers. At touchdown, the left main wheel was 6 to 8 ft from the left side of the runway (about 30 ft left of centerline), and the airplane appeared to depart the left side of the runway about 140 ft after the beginning of the wheel tracks. The snowbanks on each side of the runway were 2 to 3 ft high. Onboard data indicated that the airplane crossed the runway arrival threshold at 92 KIAS. The airplane touched down about 5 seconds later at 85 KIAS. It subsequently departed the left side of the runway and came to rest about 1,400 ft from the threshold. The data did not record any activation of the stall warning system. Postaccident examination revealed damage to the outboard right wing. The left main landing gear remained extended; however, the right main landing gear was retracted in the wheel well. Further examination revealed the right main landing gear actuator housing was fractured along the length of the housing. The fracture surface exhibited features consistent with an overstress failure. Additionally, the housing was deformed outward at the fracture consistent with an overpressure event. It is likely that the right main landing gear down lock was moved to the unlocked position when the airplane encountered the snowbank during the runway excursion. Without the down lock engaged, sideloading of the landing gear resulted in excessive hydraulic pressure within the actuator, an overstress fracture, and outward deformation of the housing. Once the hydraulic pressure was relieved due to the actuator failure the right main landing gear collapsed. The right tire likely went flat during this time. The airplane flight manual specified approach speeds of 91 KIAS and 96 KIAS with 50% flaps and operating weights of 5,000 lbs. and 5,550 lbs., respectively. Aerodynamic stall speeds with 50% flaps and 0° angle of bank were noted at 72 KIAS and 74 KIAS at operating weights of 5,200 lbs. and 5,550 lbs., respectively. The available information revealed that the landing approach was performed at an appropriate airspeed and the airplane touched down under control. However, it touched down left of the runway centerline due to the snow-covered runway and night lighting conditions. Once the left wing and left main landing gear struck the snow bank bordering the runway, the pilot was unable to maintain directional control and the airplane departed the runway. The data did not indicate any mechanical failures or malfunctions with respect to the airplane that would have precluded normal operations.

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 14 docket documents
View NTSB final reportView NTSB docket

Docket documents14

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