Englewood, CO, USA
N945SH
Raytheon B300
The airplane landed, drifted left, and struck a snowbank. The wind was from 130 degrees at 6 knots and braking action was "good." A portion of the nose landing gear upper torque knee was found on the runway. The remainder of the upper torque knee and the entire lower torque knee remained attached to the nose landing gear. These items were sent to NTSB's Materials Laboratory for metallurgical examination. According to the metallurgist's factual report, the lower torque knee was fractured in overstress at two locations: on the forward and on the aft sides of the pivot fastener bore. The aft fracture was consistent with the lower knee being loaded in tension. The forward fracture was more extensively deformed, indicating it was secondary to the aft fracture. The smaller, separated piece of the lower knee showed significant elongation and deformation of the pivot bore, consistent with the forward end of the lower knee moving downward and forward relative to the upper knee. Deformation at the fracture through the grease-fitting hole at the forward fracture location was indicative of bending and twisting out of the plane of pivot. There was no evidence of preexisting cracking, corrosion, or damage.
On January 8, 2007, at 0933 mountain standard time, a Raytheon B300, N945SH, piloted by an airline transport certificated pilot, sustained minor damage when it collided with a snow bank while landing at Centennial Airport (APA), Englewood, Colorado. Visual meteorological conditions prevailed at the time of the incident. The executive/corporate flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91, and an instrument flight rules (IFR) flight plan had been filed. The captain, first officer, and six passengers were not injured. The cross-country flight originated at Columbia, Missouri, approximately 0730 central standard time, and was en route to APA. According to the incident report and captain's statement, the flight was cleared to land on runway 17L. ATIS (automatic terminal information service) information Oscar reported the wind to be from 130 degrees at 6 knots, and braking action was "good." Estimated landing weight was 12,500 pounds, and the computed Vref speed was 101 knots. The captain said touchdown was on centerline with 8,000 feet of runway remaining. As the nose was lowered, the aircraft began to drift "quickly" to the left. Opposite rudder (but no brakes) was applied. The left main landing gear rolled onto packed snow and ice at 80 knots and the airplane decelerated rapidly as it entered the snow drift. The captain said the airplane "spun around to the left and came to rest approximately 60 degrees off runway heading, just prior to taxiway A8." A portion of the nose landing gear upper torque knee was found on the runway. The remainder of the upper torque knee and the entire lower torque knee remained attached to the nose landing gear. These items were sent to NTSB's Materials Laboratory for metallurgical examination. According to the metallurgist's factual report, the lower torque knee was fractured in overstress at two locations: on the forward and on the aft sides of the pivot fastener bore. The aft fracture was consistent with the lower knee being loaded in tension. The forward fracture was more extensively deformed, indicating it was secondary to the aft fracture. The smaller, separated piece of the lower knee showed significant elongation and deformation of the pivot bore, consistent with the forward end of the lower knee moving downward and forward relative to the upper knee. Deformation at the fracture through the grease-fitting hole at the forward fracture location was indicative of bending and twisting out of the plane of pivot. There was no evidence of preexisting cracking, corrosion, or damage. According to Raytheon, both the upper and lower torque knees of the early King Air models were aluminum. As the airplane grew in size and weight, it was felt that the upper torque knee needed to be "beefed up." Today, it is made of steel. The cockpit voice recorder (CVR) was removed from the airplane and shipped to NTSB's Vehicle Recorder Division for readout and analysis. After consultation with the CVR specialist, it was agreed that convening a CVR group and preparing a transcript would be unnecessary, and that a summary report would suffice. According to the CVR Specialist's factual report, the crew planned on a landing speed of 108 knots. The airplane was configured for landing "with landing gear down and landing flaps." The first officer noted on final approach that the aircraft was at 200 feet, 130 knots, and descending at a rate of 800 feet per minute. From the time the main gear and nose gear touched down, 1.42 seconds had elapsed. The first sounds of impact occurred 2.4 seconds later. The airplane came to a halt 5 seconds after the first sounds of impact. Weather reported at Centennial Airport (APA), Englewood, Colorado, at 0944 mountain standard time, was reported as wind from 150 degrees at 9 knots, visibility 10 statute miles, clear skies, temperature 35 degrees Fahrenheit, dew point 19 degrees Fahrenheit, and a barometric pressure setting of 30.16 inches of Mercury.
THIS CASE WAS MODIFIED 10/30/2007 Failure of the nose landing gear upper torque knee due to overstress, and the pilot's inability to maintain aircraft control.
Source: NTSB Aviation Accident Database
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